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We moved from disk storage units to disk staging storage units and took a
huge performance hit. The overhead required for disk staging, and apparent
filesystem fragmentation due to 100% utilized filesystems, forced us to
revert back to disk storage units. If performance is an issue, be wary of
disk staging storage units.
Ebon Nash
Compuware Corp.
-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]On Behalf Of Johnny
Oestergaard
Sent: Wednesday, June 09, 2004 12:41 PM
To: Paul Esson; veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Disk Based Backup
Regarding speed on disk compared to tape I would say that high-speed
tapedrives are much faster then disk except for the time it takes to load
and unload the tape. When the tape is at the right position tapes are fast.
Our 9940B should be able to take around 70 MB/s if we could feen them that
fast. I would like to see a SATA disk system that could take the same load
as just 4 of the 9940B drives.
In an installation using diskstaging I see one great thing that I think we
will use and that is most of all to stage small backups and slow backups to
disk and then let NBU stage them to tape. With a little luck we should be
able to bring our multiplexing down and thereby speed tapeduplication up.
What makes tapeduplication slow is most of all on duplexed tapes. We run
some tests on duplication speed on backups that where not duplexed some
years ago, and as I remember it we did this at almost the max speed of the
drives (We did 3 tests on 9940A drives)
I would use vault to make my off-site copies
/johnny
At 17:24 09-06-2004 +0100, Paul Esson wrote:
Folks,
I am currently deliberating over disk based backup options and would welcome
comments from those with first hand experience.
Specifically, I am trying to way up the pros and cons of using a Virtual
Tape Library versus sharing storage out to media servers from say a SATA
disk array. The latter looks attractive particularly since the introduction
in v5.0 of Disk Staging Storage Units (DSSUs). Is anyone using DSSUs
currently? With VTL there seems to be the cost issue of licensing drives as
in a regular library.
What I would like to do is write all backups initially to disk but then
stage the full backups to tape. I had hoped to create two tape copies one
to remain onsite (in a tape library) and the other to go offsite. However,
I am somewhat confused as to the NetBackup functionality required to achieve
this? If I use the DSSU the data appears to be migrated to tape as part of
the policy anyway, but how would I achieve my twin copies on tape, ideally
with different retention levels? Do I actually require to use inline copy
or even Vault (duplication) to achieve my end? The concern I have with
inline copy is that the quicker write to disk will be negated by having to
write to tape at the same time and before the job completes. As for Vault I
don't know the product at all but believe it is licensed by drive (How does
this work if your source is a disk storage unit?) and that could prove
costly. I have also read on this list adverse comments about duplication
speeds, although I would be writing from disk to tape.
All comments on any of these items very welcome.
Regards,
Paul Esson
Senior Support Engineer
Redstor Limited
Direct: +44 (0) 1224 595381
Mobile: +44 (0) 7766 906514
E-Mail: paul.esson AT redstor DOT com
Web: www.redstor.com <http://www.redstor.com/>
REDSTOR LIMITED
Torridon House
73-75 Regent Quay
Aberdeen
UK
AB11 5AR
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<DIV><SPAN class=804032317-09062004><FONT face=Arial color=#0000ff size=2>We
moved from disk storage units to disk staging storage units and took a huge
performance hit. The overhead required for disk staging, and apparent
filesystem fragmentation due to 100% utilized filesystems, forced us to revert
back to disk storage units. If performance is an issue, be wary of disk
staging storage units.</FONT></SPAN></DIV>
<DIV><SPAN class=804032317-09062004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=804032317-09062004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=804032317-09062004><FONT face=Arial color=#0000ff size=2>Ebon
Nash</FONT></SPAN></DIV>
<DIV><SPAN class=804032317-09062004><FONT face=Arial color=#0000ff
size=2>Compuware Corp.</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]<B>On Behalf Of
</B>Johnny
Oestergaard<BR><B>Sent:</B> Wednesday, June 09, 2004 12:41 PM<BR><B>To:</B>
Paul Esson; veritas-bu AT mailman.eng.auburn DOT edu<BR><B>Subject:</B> Re:
[Veritas-bu] Disk Based Backup<BR><BR></FONT></DIV>Regarding speed on disk
compared to tape I would say that high-speed tapedrives are much faster then
disk except for the time it takes to load and unload the tape. When the tape
is at the right position tapes are fast. Our 9940B should be able to take
around 70 MB/s if we could feen them that fast. I would like to see a SATA
disk system that could take the same load as just 4 of the 9940B
drives.<BR>In
an installation using diskstaging I see one great thing that I think we will
use and that is most of all to stage small backups and slow backups to disk
and then let NBU stage them to tape. With a little luck we should be able to
bring our multiplexing down and thereby speed tapeduplication up.<BR><BR>What
makes tapeduplication slow is most of all on duplexed tapes. We run some
tests
on duplication speed on backups that where not duplexed some years ago, and
as
I remember it we did this at almost the max speed of the drives (We did 3
tests on 9940A drives)<BR><BR>I would use vault to make my off-site
copies<BR><BR>/johnny<BR><BR>At 17:24 09-06-2004 +0100, Paul Esson wrote:<BR>
<BLOCKQUOTE class=cite cite="" type="cite"><FONT face=verdana
size=2>Folks,</FONT><BR> <BR><FONT face=verdana size=2>I am currently
deliberating over disk based backup options and would welcome comments from
those with first hand experience. </FONT><BR> <BR><FONT
face=verdana size=2>Specifically, I am trying to way up the pros and cons
of
using a Virtual Tape Library versus sharing storage out to media servers
from say a SATA disk array. The latter looks attractive particularly
since the introduction in v5.0 of Disk Staging Storage Units (DSSUs).
Is anyone using DSSUs currently? With VTL there seems to be the cost
issue of licensing drives as in a regular
library.</FONT><BR> <BR><FONT
face=verdana size=2>What I would like to do is write all backups initially
to disk but then stage the full backups to tape. I had hoped to
create
two tape copies one to remain onsite (in a tape library) and the other to
go
offsite. However, I am somewhat confused as to the NetBackup
functionality required to achieve this? If I use the DSSU the data
appears to be migrated to tape as part of the policy anyway, but how would
I
achieve my twin copies on tape, ideally with different retention
levels? Do I actually require to use inline copy or even Vault
(duplication) to achieve my end? The concern I have with inline copy
is that the quicker write to disk will be negated by having to write to
tape
at the same time and before the job completes. As for Vault I don't
know the product at all but believe it is licensed by drive (How does this
work if your source is a disk storage unit?) and that could prove
costly. I have also read on this list adverse comments about
duplication speeds, although I would be writing from disk to
tape.</FONT><BR> <BR><FONT face=verdana size=2>All comments on any of
these items very welcome.</FONT><BR> <BR><FONT face=verdana
size=2>Regards,</FONT><BR><BR>Paul Esson<BR>Senior Support
Engineer<BR>Redstor
Limited<BR><BR>Direct: +44
(0) 1224 595381<BR>Mobile:
+44 (0) 7766
906514<BR>E-Mail:
paul.esson AT redstor DOT
com<BR>Web:
<A href="http://www.redstor.com/";
eudora="autourl">www.redstor.com</A><BR><BR>REDSTOR LIMITED<BR>Torridon
House<BR>73-75 Regent Quay<BR>Aberdeen<BR>UK<BR>AB11
5AR<BR><BR>Disclaimer:<BR>The information included in this e-mail is of a
confidential nature and is intended only for the addressee. If you
are
not the intended addressee, any disclosure, copying or distribution by you
is prohibited and may be unlawful. Disclosure to any party other than
the addressee, whether inadvertent or otherwise is not intended to waive
privilege or confidentiality.<?xml:namespace prefix = o ns =
"urn:schemas-microsoft-com:office:office"
/><BR> </BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>
<BR>
<BR>
<BR>
<P><B><FONT SIZE=2 FACE="Arial">The contents of this e-mail are intended for
the named addressee only. It contains information that may be confidential.
Unless you are the named addressee or an authorized designee, you may not copy
or use it, or disclose it to anyone else. If you received it in error please
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