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Subject: RE: Functional Spec for Restarting Aborted Mirror Sessions
Date: Thu, 23 Oct 2008 11:21:34 -0700
Message-ID: <BB375AF679D4A34E9CA8DFA650E2B04E0C19C953@onstor-exch02.onstor.net>
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Thread-Topic: Functional Spec for Restarting Aborted Mirror Sessions
Thread-Index: Ackv1O3tEhWUVqkHQgKyrh7qzDZeLwAAYdLQASbqAuAAAFDOsAACO76gAC5Iy2AAARh9AA==
References: <BB375AF679D4A34E9CA8DFA650E2B04E0C19C765@onstor-exch02.onstor.net> <BB375AF679D4A34E9CA8DFA650E2B04E0AE22BCC@onstor-exch02.onstor.net>
From: "Deepak Veliath" <deepak.veliath@onstor.com>
To: "dl-Design Review" <dl-designreview@onstor.com>,
	"dl-Kegg Core Team" <dl-KeggCoreTeam@onstor.com>

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Hello Chris,


	*	Section 2:  I'd make it clear that this includes
baseline mirror sessions. =20

Agreed & changed.=20

	*	Section 5:  I know we're not including design details,
but I thought we wanted to document the maximum amount of data that
would be retransmitted.  (In this case, no more than 10 minutes worth of
data since checkpoints will be initiated at 10 minute intervals
(non-configurable).) =20

Changed to read that the checkpoints will be taken every 10 minutes.  I
was under the impression that this could be decided later in the
project.=20

	*	Section 6:   Paragraph 4 should clarify that an
additional snapshot will be created and transferred in addition to
completing transfer of the aborted snapshot.=20

The current "mirror start" Description text does not mention mirror
snapshots.  I do not want to introduce this into user visible
documentation now.

	*	Section 6.1:  In paragraph 1, the "newly created mirror
snapshot" is unclear.  A "mirror start" command will always create a new
mirror snapshot.  If there is an aborted mirror session outstanding, it
will attempt to restart it where it left off before proceeding to
transfer the newly created mirror snapshot.=20

Changed. =20

	*	Section 6.1:  In paragraph 2, do we cleanup the aborted
session somehow?  Is the snapshot deleted?=20

The mirroring sub-system currently cleans up mirror snapshots after a
successful mirror session so that only the two most recent mirror
snapshots are left on the source.  This logic will ensure that the
mirror snapshots created by an earlier aborted session will be cleaned
up (if they are sufficiently old).

	*	Section 9:  Item 1:  include vsvr failover on source and
target as potential reasons for a mirror session to abort.=20

Changed. =20

	*	Section 9:  Item 4:  "Revert", AKA downgrade, IS NOT
SUPPORTED, period.  There is no reason to test this. =20

I spoke to Amit regarding this after the meeting.  Since the checkpoint
information will very likely be stored in an unused portion of the
super-block, it could be done without an FS layout version change.  If
that happens then we need to test the following scenario:

	A Kegg version mirror session aborts.
	The target s/w version is downgraded and mirror sessions run
through to completion.
	Target s/w version is upgraded to Kegg and a mirror session
initiated.  It will interpret the check-point information present from
the aborted mirror sessions.

There will be logic to handle this situation in the restart logic and it
has to be tested.  Which is why I left this case in.
=20
Since this project by itself does not necessitate a layout version bump,
for this document to be complete, this test-case has to be listed.  Amit
tells me there will very likely be a layout version bump, so yes, it
might never need to be supported.
=20
The latest version of the document is once again at:

	\\mightydog\software\Kegg\Functional
Specs\RestartAbortedMirrorSessionsFuncSpec.doc
<file://mightydog/software/Kegg/Functional%20Specs/RestartAbortedMirrorS
essionsFuncSpec.doc>=20

Thanks,
veliath

=09

	ChrisV


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<DIV dir=3Dltr align=3Dleft><SPAN class=3D272450418-23102008><FONT =
color=3D#800000=20
size=3D2>Hello Chris,</FONT></SPAN></DIV><BR>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #800000 2px =
solid; MARGIN-RIGHT: 0px">
  <DIV class=3DSection1>
  <UL style=3D"MARGIN-TOP: 0in" type=3Ddisc>
    <LI class=3DMsoNormal style=3D"COLOR: navy; mso-list: l0 level1 =
lfo1"><FONT=20
    color=3Dnavy size=3D2><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial">Section=20
    2:&nbsp; I&#8217;d make it clear that this includes baseline mirror=20
    sessions.<o:p></o:p></SPAN></FONT>&nbsp;<SPAN =
class=3D272450418-23102008><FONT=20
    color=3D#800000 =
size=3D2>&nbsp;</FONT></SPAN></LI></UL></DIV></BLOCKQUOTE>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><SPAN=20
class=3D272450418-23102008><FONT color=3D#800000 size=3D2>Agreed &amp;=20
changed.</FONT>&nbsp;</SPAN></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #800000 2px =
solid; MARGIN-RIGHT: 0px">
  <UL style=3D"MARGIN-TOP: 0in" type=3Ddisc>
    <LI class=3DMsoNormal style=3D"COLOR: navy; mso-list: l0 level1 =
lfo1"><FONT=20
    color=3Dnavy size=3D2><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial">Section=20
    5:&nbsp; I know we&#8217;re not including design details, but I =
thought we wanted=20
    to document the maximum amount of data that would be retransmitted.=20
    &nbsp;(In this case, no more than 10 minutes worth of data since =
checkpoints=20
    will be initiated at 10 minute intervals=20
    (non-configurable).)<o:p></o:p></SPAN></FONT>&nbsp;<SPAN=20
    class=3D272450418-23102008><FONT color=3D#800000=20
  size=3D2>&nbsp;</FONT></SPAN></LI></UL></BLOCKQUOTE>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><SPAN=20
class=3D272450418-23102008><FONT color=3D#800000 size=3D2>Changed to =
read that the=20
checkpoints will be taken every 10 minutes.&nbsp; I was under the =
impression=20
that&nbsp;this could be decided later in the =
project.</FONT>&nbsp;</SPAN></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #800000 2px =
solid; MARGIN-RIGHT: 0px">
  <UL style=3D"MARGIN-TOP: 0in" type=3Ddisc>
    <LI class=3DMsoNormal style=3D"COLOR: navy; mso-list: l0 level1 =
lfo1"><FONT=20
    color=3Dnavy><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial">Section=20
    6:&nbsp;&nbsp; Paragraph 4 should clarify that an additional =
snapshot will=20
    be created and transferred in addition to completing transfer of the =
aborted=20
    snapshot.<FONT color=3D#800000><SPAN=20
    =
class=3D272450418-23102008>&nbsp;</SPAN></FONT></SPAN></FONT></LI></UL></=
BLOCKQUOTE>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><FONT=20
color=3Dnavy><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: Arial"><FONT=20
color=3D#800000><SPAN class=3D272450418-23102008>The =
current&nbsp;"mirror start"=20
Description text does not mention mirror snapshots.&nbsp; I do not want=20
to&nbsp;introduce&nbsp;this into user visible documentation=20
now.</SPAN></FONT></SPAN></FONT></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #800000 2px =
solid; MARGIN-RIGHT: 0px">
  <UL style=3D"MARGIN-TOP: 0in" type=3Ddisc>
    <LI class=3DMsoNormal style=3D"COLOR: navy; mso-list: l0 level1 =
lfo1"><FONT=20
    color=3Dnavy><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial">Section=20
    6.1:&nbsp; In paragraph 1, the &#8220;newly created mirror =
snapshot&#8221; is=20
    unclear.&nbsp; A &#8220;mirror start&#8221; command will always =
create a new mirror=20
    snapshot.&nbsp; If there is an aborted mirror session outstanding, =
it will=20
    attempt to restart it where it left off before proceeding to =
transfer the=20
    newly created mirror snapshot.<FONT color=3D#800000><SPAN=20
    =
class=3D272450418-23102008>&nbsp;</SPAN></FONT></SPAN></FONT></LI></UL></=
BLOCKQUOTE>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><FONT=20
color=3Dnavy><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: Arial"><FONT=20
color=3D#800000><SPAN=20
class=3D272450418-23102008>Changed.&nbsp;</SPAN><o:p></o:p></FONT></SPAN>=
</FONT>=20
</DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #800000 2px =
solid; MARGIN-RIGHT: 0px">
  <UL style=3D"MARGIN-TOP: 0in" type=3Ddisc>
    <LI class=3DMsoNormal style=3D"COLOR: navy; mso-list: l0 level1 =
lfo1"><FONT=20
    color=3Dnavy><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial">Section=20
    6.1:&nbsp; In paragraph 2, do we cleanup the aborted session =
somehow?=20
    &nbsp;Is the snapshot deleted?<SPAN class=3D272450418-23102008><FONT =

    =
color=3D#800000>&nbsp;</FONT></SPAN></SPAN></FONT></LI></UL></BLOCKQUOTE>=

<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><FONT=20
color=3Dnavy><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: Arial"><SPAN=20
class=3D272450418-23102008><FONT color=3D#800000>The mirroring=20
sub-system&nbsp;currently cleans up mirror snapshots after a successful =
mirror=20
session so that only the two most recent mirror snapshots are left on =
the=20
source.&nbsp; This logic will ensure that the mirror snapshots created =
by an=20
earlier aborted session will be cleaned up (if they are sufficiently=20
old).</FONT></SPAN></SPAN></FONT></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #800000 2px =
solid; MARGIN-RIGHT: 0px">
  <UL style=3D"MARGIN-TOP: 0in" type=3Ddisc>
    <LI class=3DMsoNormal style=3D"COLOR: navy; mso-list: l0 level1 =
lfo1"><FONT=20
    color=3Dnavy><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial">Section=20
    9:&nbsp; Item 1:&nbsp; include vsvr failover on source and target as =

    potential reasons for a mirror session to abort.<FONT =
color=3D#800000><SPAN=20
    =
class=3D272450418-23102008>&nbsp;</SPAN></FONT></SPAN></FONT></LI></UL></=
BLOCKQUOTE>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><FONT=20
color=3Dnavy><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: Arial"><FONT=20
color=3D#800000><SPAN=20
class=3D272450418-23102008>Changed.&nbsp;</SPAN><o:p></o:p></FONT></SPAN>=
</FONT>=20
</DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #800000 2px =
solid; MARGIN-RIGHT: 0px">
  <UL style=3D"MARGIN-TOP: 0in" type=3Ddisc>
    <LI class=3DMsoNormal style=3D"COLOR: navy; mso-list: l0 level1 =
lfo1"><FONT=20
    color=3Dnavy size=3D2><SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: =
Arial">Section=20
    9:&nbsp; Item 4:&nbsp; &#8220;Revert&#8221;, AKA downgrade, IS NOT =
SUPPORTED,=20
    period.&nbsp; There is no reason to test=20
    this.<o:p></o:p></SPAN></FONT>&nbsp;<SPAN =
class=3D272450418-23102008><FONT=20
    color=3D#800000 size=3D2>&nbsp;</FONT></SPAN></LI></UL></BLOCKQUOTE>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><SPAN=20
class=3D272450418-23102008><FONT color=3D#800000 size=3D2>I spoke to =
Amit regarding=20
this after the meeting.&nbsp;&nbsp;Since the checkpoint=20
information</FONT>&nbsp;<FONT color=3D#800000 size=3D2>will very likely =
be stored in=20
an unused portion of the super-block, it could be done without an FS =
layout=20
version change.&nbsp; If that happens then we need to test the following =

scenario:</FONT></SPAN></DIV>
<BLOCKQUOTE dir=3Dltr style=3D"MARGIN-RIGHT: 0px">
  <DIV class=3DMsoNormal dir=3Dltr=20
  style=3D"COLOR: navy; mso-list: l0 level1 lfo1"><SPAN=20
  class=3D272450418-23102008><FONT color=3D#800000 size=3D2>A Kegg =
version mirror=20
  session aborts.</FONT></SPAN></DIV>
  <DIV class=3DMsoNormal dir=3Dltr=20
  style=3D"COLOR: navy; mso-list: l0 level1 lfo1"><SPAN=20
  class=3D272450418-23102008><FONT color=3D#800000 size=3D2>The target =
s/w version is=20
  downgraded and mirror sessions run through to =
completion.</FONT></SPAN></DIV>
  <DIV class=3DMsoNormal dir=3Dltr=20
  style=3D"COLOR: navy; mso-list: l0 level1 lfo1"><SPAN=20
  class=3D272450418-23102008><FONT color=3D#800000 size=3D2>Target s/w =
version is=20
  upgraded to Kegg and a mirror session initiated.&nbsp; It =
will&nbsp;interpret=20
  the check-point information present from the aborted mirror=20
  sessions.</FONT></SPAN></DIV></BLOCKQUOTE>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><SPAN=20
class=3D272450418-23102008><FONT color=3D#800000 size=3D2>There will be =
logic to=20
handle this situation in the restart logic and it has to be =
tested.&nbsp; Which=20
is why I left this case in.</FONT></SPAN></DIV>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><SPAN=20
class=3D272450418-23102008><FONT color=3D#800000 =
size=3D2></FONT></SPAN>&nbsp;</DIV>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><SPAN=20
class=3D272450418-23102008><FONT color=3D#800000 size=3D2>Since this =
project by itself=20
does not necessitate a layout version bump, for this document to be =
complete,=20
this test-case has to be listed.&nbsp; Amit tells me there will very =
likely be a=20
layout version bump, so yes, it might never need to be=20
supported.</FONT></SPAN></DIV>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><SPAN=20
class=3D272450418-23102008><FONT color=3D#800000 =
size=3D2></FONT></SPAN>&nbsp;</DIV>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><SPAN=20
class=3D272450418-23102008><FONT color=3D#800000 size=3D2>The latest =
version of the=20
document is once again at:</FONT></SPAN></DIV>
<BLOCKQUOTE dir=3Dltr style=3D"MARGIN-RIGHT: 0px">
  <DIV class=3DMsoNormal dir=3Dltr=20
  style=3D"COLOR: navy; mso-list: l0 level1 lfo1"><SPAN=20
  class=3D272450418-23102008><SPAN style=3D"FONT-SIZE: 10pt; COLOR: =
maroon"><A=20
  =
href=3D"file://mightydog/software/Kegg/Functional%20Specs/RestartAbortedM=
irrorSessionsFuncSpec.doc">\\mightydog\software\Kegg\Functional=20
  =
Specs\RestartAbortedMirrorSessionsFuncSpec.doc</A></SPAN></SPAN></DIV></B=
LOCKQUOTE>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><SPAN=20
class=3D272450418-23102008><FONT color=3D#800000 =
size=3D2>Thanks,</FONT></SPAN></DIV>
<DIV class=3DMsoNormal dir=3Dltr style=3D"COLOR: navy; mso-list: l0 =
level1 lfo1"><SPAN=20
class=3D272450418-23102008><FONT color=3D#800000 =
size=3D2>veliath</FONT></SPAN></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #800000 2px =
solid; MARGIN-RIGHT: 0px">
  <P class=3DMsoNormal><FONT color=3Dnavy size=3D2><SPAN=20
  style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: =
Arial"><o:p></o:p></SPAN></FONT></P>
  <P class=3DMsoNormal><FONT color=3Dnavy size=3D2><SPAN=20
  style=3D"FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: =
Arial">ChrisV</SPAN></FONT></P></BLOCKQUOTE></BODY></HTML>

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