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[Veritas-bu] Disk Based Backup
2004-06-09 12:40:51
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Subject: |
[Veritas-bu] Disk Based Backup |
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From: |
joe AT joe DOT net (Johnny Oestergaard) |
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Date: |
Wed, 09 Jun 2004 18:40:51 +0200 |
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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
>
>REDSTOR LIMITED
>Torridon House
>73-75 Regent Quay
>Aberdeen
>UK
>AB11 5AR
>
>Disclaimer:
>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" />
>
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<html>
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 type=3Dcite class=3Dcite cite><font face=3D"verdana"=
size=3D2>Folks,</font><br>
<br>
<font face=3D"verdana" size=3D2>I am currently deliberating over disk based
backup options and would welcome comments from those with first hand
experience. </font><br>
<br>
<font face=3D"verdana" size=3D2>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=3D"verdana" size=3D2>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=3D"verdana" size=3D2>All comments on any of these items very
welcome.</font><br>
<br>
<font face=3D"verdana" size=3D2>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=3D"http://www.redstor.com/"=
eudora=3D"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 =3D o ns =3D
"urn:schemas-microsoft-com:office:office" /><br>
</blockquote></html>
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