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Subject: RE: What impact would there be to convert a 5TB filesystem?
Date: Wed, 21 Nov 2007 12:24:42 -0800
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Thread-Topic: What impact would there be to convert a 5TB filesystem?
Thread-Index: Acgse6xj8Zu/0EKSR3KB/Pwg3erNowAAEt7Q
References: <022901c82c7b$a956d9a0$684d7e0a@glasshousetech.com>
From: "Jobi Ariyamannil" <jobi.ariyamannil@onstor.com>
To: "Michael Tracy (Glasshouse)" <mtracy@css.glasshouse.com>,
	"dl-cstech" <dl-cstech@onstor.com>

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Hi Michael,

=20

Are you talking about 64k limit for subdirectories or hard links?

I am not aware of any limits on hardlinks other than 1k limit per file.

=20

If the filesystem has lots of hardlinks, the layout needs to be
converted manually using the offline command "filesystem convert".

This should not take a long time for 64k hardlinks.  We have seen layout
conversion taking around 10 minutes when the filesystem has plenty of
free space and 1million hardlinks.

The size of the filesystem has no impact on filesystem layout
conversion.

=20

Regards,

Jobi

=20

________________________________

From: Michael Tracy (Glasshouse)=20
Sent: Wednesday, November 21, 2007 12:18 PM
To: dl-cstech
Subject: What impact would there be to convert a 5TB filesystem?

=20

Hi all
Customer is at 2.2.1 and he hit the hard limit max of 64k
The answer appears to be go to 3.x  and then filesystem convert
He wants to know what impact there will be when he converts.
Is there any downtime or risk of data loss?
How long would it take to convert a 5TB filesystem with 64k hard links?

Thanks
Michael

I found this in wiki for Zonda - but it doesn't answer the above
questions
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Appropriate layout changes will be made to support the above mentioned
requirements.
Current filesystem layout version is 28, which will be incremented by
one.  All new filesystems will be created with this layout version of
29.  Since the changes between layout versions 28 and 29 are not
significant, in order to get all the benefits of the new layout, any
filesystems with layout version 28 will be automatically converted to 29
while bringing the volume online.
While converting layout versions older than 28 to a newer version,
significant amount of time is spent while converting old format link
file to the new per inode hardlink files.  If a filesystem does not have
many hardlinks, the whole conversion can be done instantly.  In order to
take advantages of the new layouts which do some of the things (for
example, delayed large file removal) differently to avoid filesystem
becoming inconsistent, any filesystems with layout versions older than
28 will be also converted to the latest supported layout while bringing
the volume online if the filesystem does not have too many hardlinks (by
checking the number of blocks of the global link inode - say, just one
block).  This is also helpful to our customers since some of the new
features introduced recently are available only with newer layouts (for
example, tree quota remove).
Also note that changing the layout version to the latest on a mirror
source volume will cause its mirror target volume to be converted during
the next mirror sync, by reverting to a snapshot taken with the new
layout on the source volume (See section 5.5).
"filesystem convert" command will convert filesystems with layout
versions older than 29 to layout version 29 layout.  This is an offline
operation and needed to convert filesystems with large number of
hardlinks.


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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'>Hi =
Michael,<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'>Are you talking about 64k limit for
subdirectories or hard links?<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 am not aware of any limits on =
hardlinks
other than 1k limit per file.<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'>If the filesystem has lots of =
hardlinks,
the layout needs to be converted manually using the offline command =
&#8220;filesystem
convert&#8221;.<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'>This should not take a long time =
for 64k
hardlinks. &nbsp;We have seen layout conversion taking around 10 minutes =
when the
filesystem has plenty of free space and 1million =
hardlinks.<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'>The size of the filesystem has no =
impact
on filesystem layout conversion.<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'>Regards,<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'>Jobi<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>

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<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span =
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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">Michael Tracy</st1:PersonName> (Glasshouse) <br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Wednesday, November =
21, 2007
12:18 PM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> dl-cstech<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> What impact =
would there
be to convert a 5TB filesystem?</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>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Hi all<br>
Customer is at 2.2.1 and he hit the hard limit max of 64k<br>
The answer appears to be go to 3.x&nbsp; and then filesystem convert<br>
He wants to know what impact there will be when he converts.<br>
Is there any downtime or risk of data loss?<br>
How long would it take to convert a 5TB filesystem with 64k hard =
links?<br>
<br>
Thanks<br>
Michael<br>
<br>
I found this in wiki for Zonda - but it doesn't answer the above =
questions<br>
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D<br>
<font color=3Dblue><span style=3D'color:blue'>Appropriate layout changes =
will be
made to support the above mentioned requirements.<br>
Current filesystem layout version is 28, which will be incremented by
one.&nbsp; All new filesystems will be created with this layout version =
of
29.&nbsp; Since the changes between layout versions 28 and 29 are not
significant, in order to get all the benefits of the new layout, any
filesystems with layout version 28 will be automatically converted to 29 =
while
bringing the volume online.<br>
While converting layout versions older than 28 to a newer version, =
significant
amount of time is spent while converting old format link file to the new =
per
inode hardlink files.&nbsp; If a filesystem does not have many =
hardlinks, the
whole conversion can be done instantly.&nbsp; In order to take =
advantages of
the new layouts which do some of the things (for example, delayed large =
file
removal) differently to avoid filesystem becoming inconsistent, any =
filesystems
with layout versions older than 28 will be also converted to the latest
supported layout while bringing the volume online if the filesystem does =
not
have too many hardlinks (by checking the number of blocks of the global =
link
inode &#8211; say, just one block).&nbsp; This is also helpful to our =
customers
since some of the new features introduced recently are available only =
with
newer layouts (for example, tree quota remove).<br>
Also note that changing the layout version to the latest on a mirror =
source
volume will cause its mirror target volume to be converted during the =
next
mirror sync, by reverting to a snapshot taken with the new layout on the =
source
volume (See section 5.5).<br>
&#8220;filesystem convert&#8221; command will convert filesystems with =
layout
versions older than 29 to layout version 29 layout.&nbsp; This is an =
offline
operation and needed to convert filesystems with large number of =
hardlinks.</span></font></span></font><o:p></o:p></p>

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