Veritas-bu

[Veritas-bu] NetBackup Disk Staging Performance Questions

2007-03-01 08:05:47
Subject: [Veritas-bu] NetBackup Disk Staging Performance Questions
From: ewilts at ewilts.org (Ed Wilts)
Date: Thu, 01 Mar 2007 07:05:47 -0600
On 2/28/2007 10:34 PM, Anthony Segran wrote:
> /Is SATA a common choice out there for DSSU's?

We use FATA drives - not much difference between them and SATA really.

> //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?/

This appears to be a NetBackup issue and we're working directly with 
Symantec engineering on our destaging performance issues.  We believe 
we've got the right people at Symantec involved, we've given them a lot 
of data, and they've already been out to visit us.  They're actively 
working this issue.  There are many factors involved and we don't know 
yet if it's a NetBackup bug, design issue, or a customer configuration 
issue.  If it's the latter, it's not going to do you much good.  The 
logs currently claim that we can't read off of disk fast enough to drive 
a single LTO-3 drive but we've demonstrated using non-NBU tools that we 
can read at 380+ MB/sec off of disk (essentially saturating the HBAs) 
and the LTO-3 isn't that fast (don't we wish!).  If I get something 
definitive that I can pass on, I'll post to the list.  You and I are not 
the only people that have posted about destaging performance.

> /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. 

We use DSSUs a *lot*.  We saw this issue regularly in pre-6.0MP4 days 
but have not seen it since.  We worked with Symantec extensively during 
the MP3 -> MP4 development cycle.  Continue working with support and 
escalate the case if you need to.  Obviously orphan images are a bug and 
they're supposed to be cleaned up automatically.

        .../Ed

-- 
Ed Wilts, Mounds View, MN, USA
mailto:ewilts at ewilts.org

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