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I know the technote specifically talks about raid 5, but in simple form,
instead of...
- look at last access time
- open file and read for backup
- adjust last access time back to original
it's now just...
- open file and read for backup
for every single file!
The extra instructions the software is performing is slowing it down, not
just the fact that it is doing reads/writes instead of just reads,
especially if you're using raid 5 in hardware on a decent array. I would
not be surprised at all if the same files moved to a raid 1 volume backed
up at the same speed.
Doing what the article says will speed up backups. Just pay really close
attention to the little disclaimer at the bottom. If you're using
software that relies on the last access time, it WILL break!!!
- Scott
"Nash, Ebon" <Ebon_Nash AT compuware DOT com>
Sent by: veritas-bu-admin AT mailman.eng.auburn DOT edu
10/30/2002 12:46 PM
To: "'paulg AT CDCNA DOT COM'" <paulg AT cdcna DOT com>,
Bruno.Bossier AT comparex DOT be,
veritas-bu AT mailman.eng.auburn DOT edu
cc:
Subject: RE: [Veritas-bu] Backing up a large amount of small
files
There is a Veritas Technote that discusses poor backup throughput
performance on RAID 5 disks. It shows how to disable the resetting of
access times which can seriously degrade performance on machines with a
lot
of smaller files. See technote 240607 on Veritas' support site for
further
information.
Ebon
-----Original Message-----
From: paulg AT CDCNA DOT COM [mailto:paulg AT CDCNA DOT COM]
Sent: Wednesday, October 30, 2002 1:39 PM
To: Bruno.Bossier AT comparex DOT be; veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Backing up a large amount of small files
You might want to consider OFM from StBernard, it definitely has an edge
over
OTM. Should run you about $600/license. While not without issues, file
checkpointing capabilities of OFM are definitely better than that of OTM.
paulg
On Oct 30, 5:36pm, <Bruno.Bossier AT comparex DOT be> wrote:
> Subject: [Veritas-bu] Backing up a large amount of small files
> We have a server with a directory which contains over 3 million files
for
a
> total amount of nearly 150 Gb. We are trying to back this up in a
> reasonable amount of time (12 to 14 hours maximum). OTM is enabled. We
have
> not succeeded so far. A lot of time is lost at the beginning of the
backup
> when the backup is going through the directory structure to check all
> files. This takes several hours. The first we already did until now is
to
> set the maximum cache size to 0 (unlimited). This stopped the errors we
saw
> in the Windows eventlog when OTM is started and then aborted after 40
> minutes, then restarted again ....
>
> Can someone give some suggestions to speed up this backup ?
>
> Thanks,
> Bruno
>
>
> _______________________________________________
> Veritas-bu maillist - Veritas-bu AT mailman.eng.auburn DOT edu
> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
>-- End of excerpt from <Bruno.Bossier AT comparex DOT be>
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<br><font size=2 face="Arial">I know the technote specifically talks about raid
5, but in simple form, instead of...</font>
<br>
<br><font size=2 face="Arial">- look at last access time</font>
<br><font size=2 face="Arial">- open file and read for backup</font>
<br><font size=2 face="Arial">- adjust last access time back to original</font>
<br>
<br><font size=2 face="Arial">it's now just...</font>
<br>
<br><font size=2 face="Arial">- open file and read for backup</font>
<br>
<br><font size=2 face="Arial">for every single file!</font>
<br>
<br><font size=2 face="Arial">The extra instructions the software is performing
is slowing it down, not just the fact that it is doing reads/writes instead of
just reads, especially if you're using raid 5 in hardware on a decent array.
I would not be surprised at all if the same files moved to a raid 1
volume backed up at the same speed.</font>
<br>
<br><font size=2 face="Arial">Doing what the article says will speed up
backups. Just pay really close attention to the little disclaimer at the
bottom. If you're using software that relies on the last access time, it
WILL break!!!</font>
<br>
<br>
<br><font size=2 face="Arial">- Scott</font>
<br>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td>
<td><font size=1 face="sans-serif"><b>"Nash, Ebon" <Ebon_Nash AT
compuware DOT com></b></font>
<br><font size=1 face="sans-serif">Sent by: veritas-bu-admin AT
mailman.eng.auburn DOT edu</font>
<p><font size=1 face="sans-serif">10/30/2002 12:46 PM</font>
<br>
<td><font size=1 face="Arial"> </font>
<br><font size=1 face="sans-serif"> To:
"'paulg AT CDCNA DOT COM'" <paulg AT cdcna DOT
com>, Bruno.Bossier AT comparex DOT be, veritas-bu AT mailman.eng.auburn DOT
edu</font>
<br><font size=1 face="sans-serif"> cc:
</font>
<br><font size=1 face="sans-serif"> Subject:
RE: [Veritas-bu] Backing up a large amount of small
files</font></table>
<br>
<br>
<br><font size=2 face="Courier New">There is a Veritas Technote that discusses
poor backup throughput<br>
performance on RAID 5 disks. It shows how to disable the resetting of<br>
access times which can seriously degrade performance on machines with a lot<br>
of smaller files. See technote 240607 on Veritas' support site for
further<br>
information.<br>
<br>
<br>
Ebon<br>
<br>
-----Original Message-----<br>
From: paulg AT CDCNA DOT COM [mailto:paulg AT CDCNA DOT COM]<br>
Sent: Wednesday, October 30, 2002 1:39 PM<br>
To: Bruno.Bossier AT comparex DOT be; veritas-bu AT mailman.eng.auburn DOT
edu<br>
Subject: Re: [Veritas-bu] Backing up a large amount of small files<br>
<br>
<br>
You might want to consider OFM from StBernard, it definitely has an edge<br>
over<br>
OTM. Should run you about $600/license. While not without issues,
file<br>
checkpointing capabilities of OFM are definitely better than that of OTM.<br>
<br>
paulg<br>
<br>
On Oct 30, 5:36pm, <Bruno.Bossier AT comparex DOT be> wrote:<br>
> Subject: [Veritas-bu] Backing up a large amount of small files<br>
> We have a server with a directory which contains over 3 million files
for<br>
a<br>
> total amount of nearly 150 Gb. We are trying to back this up in a<br>
> reasonable amount of time (12 to 14 hours maximum). OTM is enabled. We<br>
have<br>
> not succeeded so far. A lot of time is lost at the beginning of the
backup<br>
> when the backup is going through the directory structure to check all<br>
> files. This takes several hours. The first we already did until now is
to<br>
> set the maximum cache size to 0 (unlimited). This stopped the errors we<br>
saw<br>
> in the Windows eventlog when OTM is started and then aborted after 40<br>
> minutes, then restarted again ....<br>
><br>
> Can someone give some suggestions to speed up this backup ?<br>
><br>
> Thanks,<br>
> Bruno<br>
><br>
><br>
> _______________________________________________<br>
> Veritas-bu maillist - Veritas-bu AT mailman.eng.auburn DOT
edu<br>
> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu<br>
>-- End of excerpt from <Bruno.Bossier AT comparex DOT be><br>
<br>
<br>
_______________________________________________<br>
Veritas-bu maillist - Veritas-bu AT mailman.eng.auburn DOT edu<br>
http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu<br>
<br>
<br>
<br>
The contents of this e-mail are intended for the named addressee only. It<br>
contains information that may be confidential. Unless you are the named<br>
addressee or an authorized designee, you may not copy or use it, or disclose<br>
it to anyone else. If you received it in error please notify us immediately<br>
and then destroy it. <br>
<br>
_______________________________________________<br>
Veritas-bu maillist - Veritas-bu AT mailman.eng.auburn DOT edu<br>
http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu<br>
</font>
<br>
<br>
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