We're using Dell MD1000s direct attached to 3 media servers w/ 14 SATAII 500GB
Disks in a Raid 5 setup. I'm easily able to write to them at 200MB/sec+ and I
can drive LTO3s (compressed) to 120MB/sec. I occasionally look through the log
files and see less than full LTO3 capacity during duplication, but I don't
think my problem is as bad as several others who have mentioned the issue here.
We're a 100% windows environment and fragmentation has not been an issue on
our drives (yet) but we've only been in production about 6 weeks. Now all that
said, it took me about a month of configuring and reconfiguring to get all
that. I had major performance issues at the outset and slowly but surely found
an optimum configuration.
As far as SATA versus SAS or FC or SCSI - I asked this before and someone who
will go unnamed mocked me and called my drives "consumer grade." They work
just fine.
As far as failed destaging etc... I've noticed the same issues as everyone
else. I've got two methods to deal with it. 1 - I write another job to the
DSSU, once destaging kicks off after that it seems to pickup the new + the old
jobs. 2 - I have a perl script that reads the DSSU and finds images that
haven't been duplicated yet. I then have another script to duplicate those to
tape.
Good luck! I don't know how helpful I can be. I really don't know much about
Netapp but Windows works fine as a media server. Don't let the Xnix Nazis get
you down ;).
-Jonathan
________________________________
From: veritas-bu-bounces at mailman.eng.auburn.edu on behalf of Anthony Segran
Sent: Wed 2/28/2007 11:34 PM
To: veritas-bu at mailman.eng.auburn.edu
Subject: [Veritas-bu] NetBackup Disk Staging Performance Questions
Hello All
I am working with one of my favorite customers and they have raised a few
questions on issues faced in their NetBackup v6.0 MP4 environment. You would
certainly see various customer configurations out there and I am sure we have
many large customers with NBU implemented on Windows. Could you please share
your thoughts and experiences on dealing with the issues faced and highlighted
below.
Your input and feedback would be much appreciated.
Couple of things here, which revolve around DSSU's. We have problems with
fragmentation on our DSSU's (Windows Servers attached over FCP to SATA arrays
HDS 9585 and NetApp 3020). The DSSU's are over a TB in size which is causing a
real headache with defrags; we have the DSSU's in a storage unit group and have
tried a method support recommended for defrag's - namely - drop out an inactive
DSSU, defrag it, then add it back to the group. I've tried this twice without
much success due to the time it's taking - I left it for >8 hours, and the
fragmentation only improved by 1%. I suspect that the IOPS generated by a
defrag is not a good match for SATA..?
So this leads to a series of questions?
Is there any other way to resolve the fragmentation issue?
Could the DSSU get removed from the SUG, all images duplicated, tape images set
as primary and the images on disk discarded and the dssu volume reformatted...
Support (again) said that large sites with large DSSU's tend to use Unix/Linux
since the filesystems on these platforms don't suffer from fragmentation to the
same extent as NTFS. There must be large Windows only sites out there (he said
hopefully!) - can you find out what they do?
Is SATA a common choice out there for DSSU's?
We experienced slow performance during duplication, on both HDS 9585 arrays and
NetApp 3020 over FCP. We're currently talking to NetApp about 3020 performance
issues, so do you know of other NBU customers using NetApp 3020's for DSSU's?
Another DSSU related issue we're seeing is orphan images left on the DSSU from
failed/incomplete jobs. We've turned the appropriate logs on and will be
clearing these out manually and escalate again if/when we see further
occurrences. Support assure us that this is not a normal/reported issue with
NBU. Are there any "working practices" that may also trigger this outcome - I'm
conscious that the guidance we received at the start of the project was a bit
on the thin side to say the least!
On the subject of orphan files, we've also seen entries being retaining in the
tmp folders in the catalog itself some of them stretching back months. Again
support have said this is not normal - so they've been manually removed and
we're keeping a watch for further occurrences. Incidentally I asked one of our
guys to do a distribution breakdown of the files by date and the results
indicate that the issue started around the time MP4 was applied.
Kind regards
________________________________
Anthony Segran
Solution Architect - Global Strategic Partners
Symantec Australia (Pty) Limited
www.symantec.com <http://www.symantec.com/>
-----------------------------------------------------
Office: (+612) 8220 7378
Mobile: (+61408) 400 213
Fax: (+612) 8220 7004
Email: anthony_segran at symantec.com
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