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The newer disk libraries based on SATA are very fast. The only tape devices
I have tested that even came close to them in performance using Netbackup
is the IBM FC LTO Gen 2. Then, with multistreams or with a
multistream/mulitplexed backup the difference again widens edge: the disk
library solution.
I compared the EMC DL against various TLUs with SCSI DLT 7000, SDLT
220N, SDLT320, LTO gen 1, LTO gen 2 and FC LTO gen 1 and gen 2.
Pushed to its maximum aggregate performance the DL will do 450 MB/s. If
there is any single tape library that can do that, I would have to see it.
Thats not specmanship, its actual measured performance.
The new DLs in many cases save you money too by
- eliminating the SSO Option in some cases and still be able to share this
device with multiple hosts
- Can also replicate the virtual tapes to physical tapes if you're obligated
to do that. The end result is you need half the physical tapes you used to
need.
- If you are trucking off line copies to a secured site, you can eliminate
the truck middleman by putting the physical tape device there and
configuring it the
DL over a DWDM link. Simply by telling NBU to eject (in this case virtual)
tape from the virtual library will automatically start the copy to physical
tape at
the secured site. . I did this over a 200km DWDM link to a STK L180 with FC
994B tape drives. Its tough to get double digit IO performance
of anything over a single DWDM link and I was doing 17 MB/s with one stream.
But the real beauty of the DL is the benefit of RAID. That increases the
reliability of the on site backup set. When a tape drive fails, you lose a
storage device
and some aggregate performance of the TLU until the drive is replaced. If a
disk in the DL fails, no loss of performance or storage unit.
A tape device can run into a "bad tape experience" now and then doing a
backup. You won't have that with a DL. Of course you could have that with
the physical TLU device the DL might optionally have as the archiving
device, but thats not going to interfere with your backup window. The DL to
physical tape
copy process is "out of band" in respects to the Netbackup backup servers.
-----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 Nash, Ebon
Sent: Wednesday, June 09, 2004 1:26 PM
To: 'Johnny Oestergaard'; Paul Esson; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Disk Based Backup
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=020152118-09062004><FONT face=Arial color=#0000ff
size=2> The newer disk libraries based on SATA are very fast. The
only
tape devices I have tested that even came close to them in
performance using Netbackup</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff size=2>is
the
</FONT></SPAN><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2>IBM FC LTO Gen 2. Then, with multistreams or with a
multistream/mulitplexed backup the difference again widens edge: the disk
library solution.</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2> I compared the EMC DL against various TLUs
with SCSI DLT 7000, SDLT 220N, SDLT320, LTO gen 1, LTO gen 2 and FC LTO
gen
1 and gen 2. </FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2>Pushed
to its maximum aggregate performance the DL </FONT></SPAN><SPAN
class=020152118-09062004><FONT face=Arial color=#0000ff size=2>will do 450
MB/s.
If there is any single tape library that can do that, I would have to see
it.</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff size=2>Thats
not specmanship, its actual measured performance. </FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2> The new DLs in many cases save you money too
by</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2> - eliminating the SSO Option in some cases and still be able
to share this device with multiple hosts</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2>- Can also replicate the virtual tapes to </FONT></SPAN><SPAN
class=020152118-09062004><FONT face=Arial color=#0000ff size=2>physical tapes
if
you're obligated to do that. The end result is you need half the physical tapes
you used to</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2>need.</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff size=2>- If
you are trucking off line copies to a secured site, you can eliminate the truck
middleman by putting the physical tape device there and configuring it
the </FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff size=2>DL
</FONT></SPAN><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2>over a DWDM link. Simply by telling NBU to eject (in this case virtual)
tape from the virtual library will automatically start the copy to
physical
tape at </FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff size=2>the
secured site. . I did this over a 200km DWDM link to a STK L180 with FC
994B tape drives. Its tough to get double digit IO
performance</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff size=2>of
anything over a single DWDM link and I was doing</FONT> <FONT face=Arial
color=#0000ff size=2>17 MB/s with one stream. </FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004></SPAN><FONT face=Arial color=#0000ff
size=2> </FONT></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2> But the real beauty of the DL is the benefit of RAID.
That increases the reliability of the on site backup set. When a tape
drive
fails, you lose a storage device</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff size=2>and
some </FONT></SPAN><SPAN class=020152118-09062004><FONT face=Arial
color=#0000ff
size=2>aggregate performance of the TLU until the drive is replaced. If a disk
in the DL fails, no loss of performance or storage unit.</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2>
A tape device can run into a "bad tape experience" now and then doing a backup.
You won't have that with a DL. Of course you could have that
with</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff size=2>the
physical TLU device the DL might optionally have as the archiving device,
but thats not going to interfere with your backup window. The DL to physical
tape</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff size=2>copy
process is "out of band" in respects to the Netbackup backup servers.
</FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2> </FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2> </FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004></SPAN><FONT face=Arial color=#0000ff
size=2> </FONT></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2> </FONT></SPAN></DIV>
<DIV><SPAN class=020152118-09062004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=020152118-09062004></SPAN><FONT face=Tahoma><FONT size=2><SPAN
class=020152118-09062004><FONT face=Arial
color=#0000ff> </FONT></SPAN></FONT></FONT></DIV>
<DIV><FONT face=Tahoma><FONT size=2><SPAN
class=020152118-09062004> </SPAN>-----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>Nash,
Ebon<BR><B>Sent:</B> Wednesday, June 09, 2004 1:26 PM<BR><B>To:</B> 'Johnny
Oestergaard'; Paul Esson; veritas-bu AT mailman.eng.auburn DOT
edu<BR><B>Subject:</B>
RE: [Veritas-bu] Disk Based Backup<BR><BR></DIV></FONT></FONT>
<BLOCKQUOTE style="MARGIN-RIGHT: 0px">
<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><BR><BR><BR>
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the
named addressee only. It contains information that may be confidential.
Unless
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