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Subject: RE: snapshot autoremove question
Date: Tue, 13 Nov 2007 20:11:30 -0800
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From: "Narayan Venkat" <narayan.venkat@onstor.com>
To: "Paul Hammer" <paul.hammer@onstor.com>,
	"Eric Barrett" <eric.barrett@onstor.com>,
	"Tim Gardner" <tim.gardner@onstor.com>,
	"Joshua Goldenhar" <joshua.goldenhar@onstor.com>,
	"Henry Lau" <henry.lau@onstor.com>,
	"dl-Design Review" <dl-designreview@onstor.com>
Cc: "Sandrine Boulanger" <sandrine.boulanger@onstor.com>,
	"Vikas Saini" <vikas.saini@onstor.com>,
	"Manohar Divate" <manohar.divate@onstor.com>,
	"Dennis Arellano" <dennis.arellano@onstor.com>

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=20

Yeah, but if you are designing the capability then we may as well design
it right.  You can make the same argument with Autogrow.  Autogrow
allows you to automatically grow a file system when it is full.  What is
your definition of full in the case of Autogrow?  Why set a high water
mark?

=20

Let's not get wrapped around in semantics here.  Let's design in
correctly.  Where is the data loss coming from?

=20

Narayan Venkat=20
Vice President, Marketing=20
ONStor, Inc.=20
Tel: (408) 963-2404=20
Cell: (408) 221-4297.=20

________________________________

From: Paul Hammer=20
Sent: Tuesday, November 13, 2007 8:07 PM
To: Narayan Venkat; Eric Barrett; Tim Gardner; Joshua Goldenhar; Henry
Lau; dl-Design Review
Cc: Sandrine Boulanger; Vikas Saini; Manohar Divate; Dennis Arellano
Subject: RE: snapshot autoremove question

=20

The data loss point is from me.

=20

The MRD states:

Auto Remove Snapshots. We need a configurable ability to auto remove
snapshots when filesystem gets full.

=20

Now we are going down a path of deleting snapshots at any water mark and
not conditionaly as the MRD stated when the file system is full.  If
this is what is/was really wanted we should have captured that in the
MRD, at this point the spec and the MRD don't agree. Which is correct?

=20

-Paul

=20

________________________________

From: Narayan Venkat
Sent: Tue 11/13/2007 5:03 PM
To: Eric Barrett; Tim Gardner; Paul Hammer; Joshua Goldenhar; Henry Lau;
dl-Design Review
Cc: Sandrine Boulanger; Vikas Saini; Manohar Divate; Dennis Arellano
Subject: RE: snapshot autoremove question

Since I am not in dl-design review, I am seeing this thread late.  I
agree with Eric's statements that we should not impose an arbitrary
requirement of autogrow before deleting a snapshot.  Where is the
"secondary data loss" argument coming from?  I don't understand it.  Why
would we lose data if snapshot reclamation and Autogrow work as
designed?  What am I missing?

=20

I'd vote for keeping the design in such a way that Autogrow and Snapshot
removal are independent and tunable separately.  This is how other
vendors do it. =20

=20

Narayan Venkat=20
Vice President, Marketing=20
ONStor, Inc.=20
Tel: (408) 963-2404=20
Cell: (408) 221-4297.=20

________________________________

From: Eric Barrett=20
Sent: Monday, November 12, 2007 8:58 AM
To: Tim Gardner; Paul Hammer; Joshua Goldenhar; Henry Lau; dl-Design
Review
Cc: Sandrine Boulanger; Vikas Saini; Manohar Divate; Dennis Arellano
Subject: RE: snapshot autoremove question

=20

I have to add also that I don't agree with the "secondary data loss"
argument.  ARHWM would be elective and therefore no different than any
other cleanup job, such as a Unix system sweeping up files in /tmp, or a
job to delete backup archive images.

=20

=20

________________________________

From: Eric Barrett=20
Sent: Monday, November 12, 2007 8:54 AM
To: Tim Gardner; Paul Hammer; Joshua Goldenhar; Henry Lau; dl-Design
Review
Cc: Sandrine Boulanger; Vikas Saini; Manohar Divate; Dennis Arellano
Subject: RE: snapshot autoremove question

My feedback to Henry before the meeting was that as an admin, I'd be
pissed at the arbitrary requirement that I autogrow stuff before I
automatically delete snapshots.  My own personal preference would be to
delete snapshots first.  I can't imagine I'm the only one.

=20

This is especially true since the implementation was changed so that we
do NOT guarantee the user does not receive ENOSPC because of a
snapshot's disk consumption.

=20

If linking ARHWM and AGHWM increases complexity of the user interaction,
complexity of user understanding, complexity of testing, complexity of
implementation, AND in the end results in a LOSS of functionality, why
do it that way?

=20

=20

________________________________

From: Tim Gardner=20
Sent: Friday, November 09, 2007 11:15 PM
To: Paul Hammer; Joshua Goldenhar; Henry Lau; dl-Design Review
Cc: Sandrine Boulanger; Vikas Saini; Manohar Divate; Dennis Arellano
Subject: RE: snapshot autoremove question

Paul,

=20

This idea was discussed in detail during the design review. The
conclusion was that autogrow and

auto snapshot removal should not be coupled for several reasons.

=20

Coupling them significantly increases the complexity of the design and
implementation.

It will result in more test cases, not less, than the current proposal.

It will increase the complexity of the documentation.

It is more likely to result in support calls.

=20

Consider the workflow where a user sets an ARHWM of 80% with autogrow
disabled.

What do we do when the user later enables autogrow with a 90% HWM?

Do we disable snapshot auro removal because it has a lower HWM?

Do we silently ignore the 80% HWM and instead use a HWM above 90%?

Do we outright change the HWM to something larger then 80%?

De we set if back if autogrow is later disabled?

What HWM do we display to the user when a vol show is done?

=20

It was also thought that customers may want to intentionally set the
ARHWM lower than

the autogrow HWM. Without actually asking customers, we really don't
know.

The consensus was that we should give customers the choice and utilize
the best

practices guide to document implications of various settings.

=20

Tim


=20

________________________________

From: Paul Hammer
Sent: Fri 11/9/2007 8:46 PM
To: Joshua Goldenhar; Henry Lau; dl-Design Review
Cc: Sandrine Boulanger; Vikas Saini; Manohar Divate; Dennis Arellano
Subject: RE: snapshot autoremove question

Hi All,

=20

Like to have the design changed slightly, think that if the user has
autogrow enabled that the HWM to trigger a snapshot deletion cannot be
set to a lower value then the autogrow value (we do not want to lose
secondary data sets, that is essentially data loss), the code must catch
this issue and trigger an error message and prevent the cfg. The
marketing  requirement (not spec) was to free up space by deleting
snapshots if the customer was going to run out of disk space (i.e.
autogrow turned off or out of luns with autogrow on), the requirement
was not about when the deletion should be triggered (at what amount of
capacity was left) or allowing a HWM for activating the deletion. Having
the delete happen before the autogrow adds to many unnecessary test
permutations.  Granted QA must test the condition where AG is set to on
and no free luns are available, if the delete snapshots option is set in
this case then the Snapshot  will be deleted to buy some head room.

=20

Please keep in mind what the requirement stated (not the spec), don't
want to get into a protracted discussion on would we allow snapshots to
be deleted at any HWM, that would be a very different different
requirement.

=20

If the user is going without autogrow being enabled they can set the HWM
to delete snapshots to what ever value they want, would be surprised
that anyone would set it at anything other than 98% or so (given what
the requirment states).

=20

Thanks,

=20

-Paul

=20

________________________________

From: Joshua Goldenhar
Sent: Fri 11/9/2007 1:25 PM
To: Henry Lau; dl-Design Review
Cc: Sandrine Boulanger; Vikas Saini; Manohar Divate; Dennis Arellano
Subject: RE: snapshot autoremove question

Thanks Henry - I see that this mentions the fact that you cannot pin
scheduled snapshots and mentions setting autogrow in such a way that
infers it is independent.

=20

I'm sure Dennis will work his magic to turn this into fabulous
documentation ;-)

-Josh=20

Josh Goldenhar=20
Phone: 408 963 2408, Cell: 408 547 7693=20

________________________________

From: Henry Lau=20
Sent: Friday, November 09, 2007 11:53 AM
To: Joshua Goldenhar; dl-Design Review
Cc: Sandrine Boulanger; Vikas Saini; Manohar Divate
Subject: RE: snapshot autoremove question

=20

Hi Joshua,

=20

Please check the best practice section in section 8.1 of the doc.


=20

/n/software/FileSystem/snapshot_management_R98_autoremove.doc

=20

Thanks,

Henry

=20

________________________________

From: Joshua Goldenhar=20
Sent: Friday, November 09, 2007 11:35 AM
To: Jobi Ariyamannil; John Keiffer; dl-Design Review
Cc: Sandrine Boulanger; Vikas Saini; Manohar Divate
Subject: RE: snapshot autoremove question

=20

Thanks Jobi.

=20

These types of questions came up in the last design review and were
discussed at length.

=20

I think a simple rewording of your problem statement can illuminate the
overall design principle we ended up sticking to:

"I would like to understand why we are willing to possibly delete all of
a customer's snapshots, if they have set and reached their autoremoval
high water mark (ARHWM)." Becomes: "...why is the customer willing to
possibly delete all of their snapshots..."

=20

As Jobi mentioned, the customer optionally turns this feature on. It's
our job to make sure the documentation and best practices guides issue
this warning and make operation as clear and understandable as possible.

=20

If we come up with an arbitrary algorithm to preserve snapshots, there
will always be a customer that will say "why did you do it THAT way? - I
would rather have had XYZ..."=20

=20

I did not know we cannot pin the scheduled snapshots - I imagine we'll
get an RFE in the future to auto-pin snapshots or set a preservation
threshold on scheduled snapshots.=20

=20

For now though I really feel the simplicity of the feature as
implemented makes it easy to understand and makes the "dangers" easy to
understand also.

-Josh=20

Josh Goldenhar=20
Phone: 408 963 2408, Cell: 408 547 7693=20

________________________________

From: Jobi Ariyamannil=20
Sent: Friday, November 09, 2007 10:13 AM
To: John Keiffer; dl-Design Review
Cc: Sandrine Boulanger; Vikas Saini; Manohar Divate
Subject: RE: snapshot autoremove question

=20

Snapshot auto removal is an optional feature somebody needs to turn on.
If they set the HWM too low, they may end up losing the snapshots.

I don't see any need of setting that below 98%.  The need for removing
snapshots automatically is needed when filesystem operates in close to
full conditions and prevent applications running into ENOSPC because of
the space pinned by snapshots.  By providing an option for the user to
specify that threshold, we ended up with all these interesting
possibilities.

=20

Regards,

Jobi

=20

________________________________

From: John Keiffer=20
Sent: Friday, November 09, 2007 10:05 AM
To: dl-Design Review
Cc: Sandrine Boulanger; Vikas Saini; Manohar Divate
Subject: snapshot autoremove question

[opens mouth]

=20

I would like to understand why we are willing to possibly delete all of
a customer's snapshots, if they have set and reached their autoremoval
high water mark (ARHWM).=20

=20

It seems that if users in the field are keeping a lot of snapshots that
this might not be a problem, since deleting some might free up the
necessary space. If users in the field are only scheduling a smaller
number of snapshots to be taken it is more likely that we might end up
deleting them all.=20

=20

Example problem: I ran it an issue where after creating a large file
(using pre-allocation), my volume usage was over the ARHWM. I then
deleted the large file. However, because both the snapshot deletion and
file deletion happen in the background, the snapshots deletion happened
before the large file was removed and the volume usage went back down.
So I ended up losing my file and my snapshots.

=20

Since we cannot pin weekly, daily, or hourly snapshots, and they are
likely to be the most current, it seems like we should keep at least
one. Some of us in QA think it might be nice to keep one of each, but at
a minimum it seems that we should at least keep the most current. If the
last unpinned snapshot needs to be deleted in order to free up space,
there are bigger issues to deal with.

=20

[inserts foot]

=20

Thank you,

John Keiffer

=20

=20


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<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
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<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Yeah, but if you are designing the
capability then we may as well design it right. &nbsp;You can make the =
same argument
with Autogrow.&nbsp; Autogrow allows you to automatically grow a file =
system when it
is full. &nbsp;What is your definition of full in the case of =
Autogrow?&nbsp; Why set a
high water mark?<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Let&#8217;s not get wrapped around =
in
semantics here. &nbsp;Let&#8217;s design in correctly.&nbsp; Where is =
the data loss
coming from?<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<div>

<p><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:
Arial;color:navy'>Narayan Venkat</span></font><font color=3Dnavy><span
style=3D'color:navy'> <br>
</span></font><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial;color:navy'>Vice President, =
Marketing</span></font><font
color=3Dnavy><span style=3D'color:navy'> <br>
</span></font><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial;color:navy'>ONStor, Inc.</span></font><font =
color=3Dnavy><span
style=3D'color:navy'> <br>
</span></font><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial;color:navy'>Tel: (408) 963-2404</span></font><font
color=3Dnavy><span style=3D'color:navy'> <br>
</span></font><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial;color:navy'>Cell: (408) 221-4297.</span></font><font
color=3Dnavy><span style=3D'color:navy'> </span></font><o:p></o:p></p>

</div>

<div>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
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<hr size=3D2 width=3D"100%" align=3Dcenter tabindex=3D-1>

</span></font></div>

<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font =
size=3D2
face=3DTahoma><span style=3D'font-size:10.0pt;font-family:Tahoma'> Paul =
Hammer <br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Tuesday, November =
13, 2007
8:07 PM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> Narayan Venkat; =
<st1:PersonName
w:st=3D"on">Eric Barrett</st1:PersonName>; <st1:PersonName =
w:st=3D"on">Tim Gardner</st1:PersonName>;
<st1:PersonName w:st=3D"on">Joshua Goldenhar</st1:PersonName>; Henry =
Lau; dl-Design
Review<br>
<b><span style=3D'font-weight:bold'>Cc:</span></b> Sandrine Boulanger; =
Vikas
Saini; Manohar Divate; Dennis Arellano<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> RE: snapshot =
autoremove
question</span></font><o:p></o:p></p>

</div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<div id=3DidOWAReplyText77646>

<div>

<p class=3DMsoNormal><font size=3D2 color=3Dblack face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:black'>The data loss point is from =
me.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 color=3Dblack face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:black'>The MRD =
states:</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><em><b><i><font size=3D2 color=3Dblack =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial;color:black;font-weight:bold'=
>Auto
Remove Snapshots. We need a configurable ability to auto remove =
snapshots when
filesystem gets full.</span></font></i></b></em><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Now we are going down a path of deleting snapshots at =
any
water mark and not conditionaly as the MRD stated when the file system =
is
full.&nbsp;&nbsp;If this is what is/was really wanted we should have =
captured
that in the MRD, at this point the spec and the MRD don't agree. Which =
is
correct?</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>-Paul</span></font><o:p></o:p></p>

</div>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabIndex=3D-1>

</span></font></div>

<p class=3DMsoNormal style=3D'margin-bottom:12.0pt'><b><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</spa=
n></font></b><font
size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'> Narayan
Venkat<br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Tue 11/13/2007 5:03 =
PM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> <st1:PersonName =
w:st=3D"on">Eric
 Barrett</st1:PersonName>; <st1:PersonName w:st=3D"on">Tim =
Gardner</st1:PersonName>;
Paul Hammer; <st1:PersonName w:st=3D"on">Joshua =
Goldenhar</st1:PersonName>; Henry
Lau; dl-Design Review<br>
<b><span style=3D'font-weight:bold'>Cc:</span></b> Sandrine Boulanger; =
Vikas
Saini; Manohar Divate; Dennis Arellano<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> RE: snapshot =
autoremove
question</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Since I am not in dl-design review, =
I am
seeing this thread late. &nbsp;I agree with Eric&#8217;s statements that =
we
should not impose an arbitrary requirement of autogrow before deleting a
snapshot. &nbsp;Where is the &#8220;secondary data loss&#8221; argument =
coming
from? &nbsp;I don&#8217;t understand it.&nbsp; Why would we lose data if
snapshot reclamation and Autogrow work as designed?&nbsp; What am I =
missing?</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>I&#8217;d vote for keeping the =
design in
such a way that Autogrow and Snapshot removal are independent and =
tunable
separately. &nbsp;This is how other vendors do it. =
&nbsp;</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<div>

<p><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:
Arial;color:navy'>Narayan Venkat</span></font><font color=3Dnavy><span
style=3D'color:navy'> <br>
</span></font><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial;color:navy'>Vice President, =
Marketing</span></font><font
color=3Dnavy><span style=3D'color:navy'> <br>
</span></font><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial;color:navy'>ONStor, Inc.</span></font><font =
color=3Dnavy><span
style=3D'color:navy'> <br>
</span></font><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial;color:navy'>Tel: (408) 963-2404</span></font><font
color=3Dnavy><span style=3D'color:navy'> <br>
</span></font><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial;color:navy'>Cell: (408) 221-4297.</span></font><font
color=3Dnavy><span style=3D'color:navy'> </span></font><o:p></o:p></p>

</div>

<div>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabIndex=3D-1>

</span></font></div>

<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font =
size=3D2
face=3DTahoma><span style=3D'font-size:10.0pt;font-family:Tahoma'> =
<st1:PersonName
w:st=3D"on">Eric Barrett</st1:PersonName> <br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Monday, November =
12, 2007
8:58 AM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> <st1:PersonName =
w:st=3D"on">Tim
 Gardner</st1:PersonName>; Paul Hammer; <st1:PersonName =
w:st=3D"on">Joshua
 Goldenhar</st1:PersonName>; Henry Lau; dl-Design Review<br>
<b><span style=3D'font-weight:bold'>Cc:</span></b> Sandrine Boulanger; =
Vikas
Saini; Manohar Divate; Dennis Arellano<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> RE: snapshot =
autoremove
question</span></font><o:p></o:p></p>

</div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>I have to add also that I don't agree with the
&quot;secondary data loss&quot; argument.&nbsp; ARHWM would be elective =
and
therefore no different than any other cleanup job, such as a Unix system
sweeping up files in /tmp, or a job to delete backup archive =
images.</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabIndex=3D-1>

</span></font></div>

<p class=3DMsoNormal style=3D'margin-bottom:12.0pt'><b><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</spa=
n></font></b><font
size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'> <st1:PersonName
w:st=3D"on">Eric Barrett</st1:PersonName> <br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Monday, November =
12, 2007
8:54 AM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> <st1:PersonName =
w:st=3D"on">Tim
 Gardner</st1:PersonName>; Paul Hammer; <st1:PersonName =
w:st=3D"on">Joshua
 Goldenhar</st1:PersonName>; Henry Lau; dl-Design Review<br>
<b><span style=3D'font-weight:bold'>Cc:</span></b> Sandrine Boulanger; =
Vikas
Saini; Manohar Divate; Dennis Arellano<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> RE: snapshot =
autoremove
question</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>My feedback to Henry before the meeting was that as =
an
admin, I'd be pissed at the arbitrary requirement that I autogrow stuff =
before
I automatically delete snapshots.&nbsp; My own personal preference would =
be to
delete snapshots first.&nbsp; I can't imagine I'm the only =
one.</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>This is especially true&nbsp;since the implementation =
was
changed so that we do NOT guarantee the user does not receive ENOSPC =
because of
a snapshot's disk consumption.</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>If linking ARHWM and AGHWM increases complexity of =
the user
interaction, complexity of user understanding, complexity of testing,
complexity of implementation, AND in the end results in a LOSS of
functionality, why do it that way?</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabIndex=3D-1>

</span></font></div>

<p class=3DMsoNormal style=3D'margin-bottom:12.0pt'><b><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</spa=
n></font></b><font
size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'> <st1:PersonName
w:st=3D"on">Tim Gardner</st1:PersonName> <br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Friday, November =
09, 2007
11:15 PM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> Paul Hammer; =
<st1:PersonName
w:st=3D"on">Joshua Goldenhar</st1:PersonName>; Henry Lau; dl-Design =
Review<br>
<b><span style=3D'font-weight:bold'>Cc:</span></b> Sandrine Boulanger; =
Vikas
Saini; Manohar Divate; Dennis Arellano<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> RE: snapshot =
autoremove
question</span></font><o:p></o:p></p>

<div id=3DidOWAReplyText8728>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Paul,</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>This idea was discussed in detail during the design =
review.
The conclusion was that autogrow and</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>auto snapshot removal should not be coupled for =
several
reasons.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Coupling them significantly increases the complexity =
of the
design and implementation.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>It will result in more test cases, not less, than the
current proposal.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>It will increase the complexity of the =
documentation.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>It is more likely to result in support =
calls.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Consider the workflow where a user sets an ARHWM of =
80% with
autogrow disabled.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>What do we do when the user later enables autogrow =
with a
90% HWM?</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Do we disable snapshot auro removal because it has a =
lower
HWM?</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Do we silently ignore the 80% HWM and instead use a =
HWM
above 90%?</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Do we outright change the HWM to something larger =
then 80%?</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>De we set if back if autogrow is later =
disabled?</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>What HWM do we display to the user when a vol show is =
done?</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>It was also thought that customers may want to =
intentionally
set the ARHWM lower than</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>the autogrow HWM. Without actually asking customers, =
we really
don't know.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>The consensus was that we should give customers the =
choice
and utilize the best</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>practices guide to document implications of various
settings.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>Tim<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><br>
&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabIndex=3D-1>

</span></font></div>

</div>

<div>

<p class=3DMsoNormal style=3D'margin-bottom:12.0pt'><b><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</spa=
n></font></b><font
size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'> Paul
Hammer<br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Fri 11/9/2007 8:46 =
PM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> <st1:PersonName =
w:st=3D"on">Joshua
 Goldenhar</st1:PersonName>; Henry Lau; dl-Design Review<br>
<b><span style=3D'font-weight:bold'>Cc:</span></b> Sandrine Boulanger; =
Vikas
Saini; Manohar Divate; Dennis Arellano<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> RE: snapshot =
autoremove
question</span></font><o:p></o:p></p>

</div>

</div>

<div>

<div id=3DidOWAReplyText11426>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Hi All,</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Like to have the design changed slightly, think that =
if the
user has autogrow enabled that the HWM to trigger a snapshot deletion =
cannot be
set to a lower value then the autogrow value (we do not want to lose =
secondary
data sets, that is essentially data loss),&nbsp;the code must catch this =
issue
and trigger an error message and prevent the cfg. The marketing
&nbsp;requirement (not spec) was to free up space by deleting snapshots =
if the
customer was going to run out of disk space (i.e. autogrow turned off or =
out of
luns with autogrow on), the requirement was not about when the deletion =
should
be triggered (at what amount of capacity was left) or allowing a HWM for
activating the deletion. Having the delete happen before the autogrow =
adds to
many unnecessary test permutations.&nbsp; Granted QA must test the =
condition
where AG is set to on and no free luns are available, if the delete =
snapshots
option is set in this case then the Snapshot &nbsp;will be deleted to =
buy some
head room.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Please keep in mind what the requirement stated (not =
the
spec), don't want to get into a protracted discussion on would we allow
snapshots to be deleted at any HWM, that would be a very different =
different
requirement.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>If the user is going without autogrow being enabled =
they can
set the HWM to delete snapshots to what ever value they want, would be
surprised that anyone would set it at anything other than 98% or so =
(given what
the requirment states).</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Thanks,</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>-Paul</span></font><o:p></o:p></p>

</div>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabIndex=3D-1>

</span></font></div>

<p class=3DMsoNormal style=3D'margin-bottom:12.0pt'><b><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</spa=
n></font></b><font
size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'> <st1:PersonName
w:st=3D"on">Joshua Goldenhar</st1:PersonName><br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Fri 11/9/2007 1:25 =
PM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> Henry Lau; dl-Design =
Review<br>
<b><span style=3D'font-weight:bold'>Cc:</span></b> Sandrine Boulanger; =
Vikas
Saini; Manohar Divate; Dennis Arellano<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> RE: snapshot =
autoremove
question</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Thanks Henry &#8211; I see that =
this
mentions the fact that you cannot pin scheduled snapshots and mentions =
setting
autogrow in such a way that infers it is =
independent.</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>I&#8217;m sure Dennis will work his =
magic
to turn this into fabulous documentation =
;-)</span></font><o:p></o:p></p>

<div>

<p><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:
Arial;color:navy'>-Josh</span></font><font color=3Dnavy><span =
style=3D'color:navy'>
</span></font><o:p></o:p></p>

<p><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:
Arial;color:navy'>Josh Goldenhar</span></font><font color=3Dnavy><span
style=3D'color:navy'> <br>
</span></font><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial;color:navy'>Phone: 408 963 2408, Cell: 408 547 =
7693</span></font><font
color=3Dnavy><span style=3D'color:navy'> </span></font><o:p></o:p></p>

</div>

<div>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabIndex=3D-1>

</span></font></div>

<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font =
size=3D2
face=3DTahoma><span style=3D'font-size:10.0pt;font-family:Tahoma'> Henry =
Lau <br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Friday, November =
09, 2007
11:53 AM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> <st1:PersonName =
w:st=3D"on">Joshua
 Goldenhar</st1:PersonName>; dl-Design Review<br>
<b><span style=3D'font-weight:bold'>Cc:</span></b> Sandrine Boulanger; =
Vikas
Saini; Manohar Divate<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> RE: snapshot =
autoremove
question</span></font><o:p></o:p></p>

</div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Hi =
Joshua,</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Please check the best practice =
section in
section 8.1 of the
doc.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nb=
sp; </span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>/n/software/FileSystem/snapshot_mana=
gement_R98_autoremove.doc</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Thanks,</span></font><o:p></o:p></p>=


<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Henry</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<div>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabIndex=3D-1>

</span></font></div>

<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font =
size=3D2
face=3DTahoma><span style=3D'font-size:10.0pt;font-family:Tahoma'> =
<st1:PersonName
w:st=3D"on">Joshua Goldenhar</st1:PersonName> <br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Friday, November =
09, 2007
11:35 AM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> Jobi Ariyamannil; =
<st1:PersonName
w:st=3D"on">John Keiffer</st1:PersonName>; dl-Design Review<br>
<b><span style=3D'font-weight:bold'>Cc:</span></b> Sandrine Boulanger; =
Vikas
Saini; Manohar Divate<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> RE: snapshot =
autoremove
question</span></font><o:p></o:p></p>

</div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Thanks =
Jobi.</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>These types of questions came up in =
the
last design review and were discussed at =
length.</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>I think a simple rewording of your =
problem
statement can illuminate the overall design principle we ended up =
sticking to:</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>&#8220;</span></font><font size=3D2
face=3DArial><span style=3D'font-size:10.0pt;font-family:Arial'>I would =
like to
understand why we are willing to possibly delete all of a =
customer&#8217;s
snapshots, if they have set and reached their autoremoval high water =
mark
(ARHWM).&#8221; <font color=3D"#333399"><span =
style=3D'color:#333399'>Becomes:</span></font>
&#8220;&#8230;why is the customer willing to possibly delete all of =
their
snapshots&#8230;&#8221;</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>As Jobi mentioned, the customer =
optionally
turns this feature on. It&#8217;s our job to make sure the documentation =
and
best practices guides issue this warning and make operation as clear and
understandable as possible.</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>If we come up with an arbitrary =
algorithm
to preserve snapshots, there will always be a customer that will say =
&#8220;why
did you do it THAT way? &#8211; I would rather have had =
XYZ&#8230;&#8221; </span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>I did not know we cannot pin the =
scheduled
snapshots &#8211; I imagine we&#8217;ll get an RFE in the future to =
auto-pin
snapshots or set a preservation threshold on scheduled snapshots. =
</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>For now though I really feel the
simplicity of the feature as implemented makes it easy to understand and =
makes
the &#8220;dangers&#8221; easy to understand =
also.</span></font><o:p></o:p></p>

<div>

<p><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:
Arial;color:navy'>-Josh</span></font><font color=3Dnavy><span =
style=3D'color:navy'>
</span></font><o:p></o:p></p>

<p><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;font-family:
Arial;color:navy'>Josh Goldenhar</span></font><font color=3Dnavy><span
style=3D'color:navy'> <br>
</span></font><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial;color:navy'>Phone: 408 963 2408, Cell: 408 547 =
7693</span></font><font
color=3Dnavy><span style=3D'color:navy'> </span></font><o:p></o:p></p>

</div>

<div>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabIndex=3D-1>

</span></font></div>

<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font =
size=3D2
face=3DTahoma><span style=3D'font-size:10.0pt;font-family:Tahoma'> Jobi =
Ariyamannil
<br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Friday, November =
09, 2007
10:13 AM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> <st1:PersonName =
w:st=3D"on">John
 Keiffer</st1:PersonName>; dl-Design Review<br>
<b><span style=3D'font-weight:bold'>Cc:</span></b> Sandrine Boulanger; =
Vikas
Saini; Manohar Divate<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> RE: snapshot =
autoremove
question</span></font><o:p></o:p></p>

</div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:blue'>Snapshot auto removal is an =
optional
feature somebody needs to turn on.&nbsp; If they set the HWM too low, =
they may
end up losing the snapshots.</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:blue'>I don't see any need of setting =
that below
98%.&nbsp; The need for removing snapshots automatically is needed when
filesystem operates in close to full conditions and prevent applications
running into ENOSPC because of the space pinned by snapshots.&nbsp; By
providing an option for the user to specify that threshold, we ended up =
with
all these interesting possibilities.</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:blue'>Regards,</span></font><o:p></o:p></p=
>

<p class=3DMsoNormal><font size=3D2 color=3Dblue face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:blue'>Jobi</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabIndex=3D-1>

</span></font></div>

<p class=3DMsoNormal style=3D'margin-bottom:12.0pt'><b><font size=3D2 =
face=3DTahoma><span
style=3D'font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</spa=
n></font></b><font
size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;font-family:Tahoma'> <st1:PersonName
w:st=3D"on">John Keiffer</st1:PersonName> <br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Friday, November =
09, 2007
10:05 AM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> dl-Design Review<br>
<b><span style=3D'font-weight:bold'>Cc:</span></b> Sandrine Boulanger; =
Vikas
Saini; Manohar Divate<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> snapshot =
autoremove
question</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>[opens =
mouth]</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>I would like to understand why we are willing to =
possibly
delete all of a customer&#8217;s snapshots, if they have set and reached =
their
autoremoval high water mark (ARHWM). </span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>It seems that if users in the field are keeping a lot =
of
snapshots that this might not be a problem, since deleting some might =
free up
the necessary space. If users in the field are only scheduling a smaller =
number
of snapshots to be taken it is more likely that we might end up deleting =
them
all. </span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D2 =
face=3DArial><span
style=3D'font-size:10.0pt;font-family:Arial'>Example problem: I ran it =
an issue
where after creating a large file (using pre-allocation), my volume =
usage was
over the ARHWM. I then deleted the large file. However, because both the
snapshot deletion and file deletion happen in the background, the =
snapshots
deletion happened before the large file was removed and the volume usage =
went
back down. So I ended up losing my file and my =
snapshots.</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Since we cannot pin weekly, daily, or hourly =
snapshots, and
they are likely to be the most current, it seems like we should keep at =
least
one. Some of us in QA think it might be nice to keep one of each, but at =
a
minimum it seems that we should at least keep the most current.<font
color=3Dnavy><span style=3D'color:navy'> </span></font>If the last =
unpinned
snapshot needs to be deleted in order to free up space, there are bigger =
issues
to deal with.</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>[inserts =
foot]</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Thank you,</span></font><o:p></o:p></p>

<p class=3DMsoNormal><st1:PersonName w:st=3D"on"><font size=3D2 =
face=3DArial><span
 style=3D'font-size:10.0pt;font-family:Arial'>John =
Keiffer</span></font></st1:PersonName><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

</div>

</div>

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