Re: [Veritas-bu] Destaging going slow
2010-06-24 19:02:12
We have pretty good DSSU destaging to tape performance.
Looks like it’s running at between 200GB to 300GB per hour
from DSSU to tape – it’s a bit slower if you have lots of small
backup images.
We have 10 LTO4 drives a I’ve found that performance is
improved if you limit the number of jobs destaging from a particular DSSU (RAID5)
at any one time.
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of WALLEBROEK
Bart
Sent: Thursday, 24 June 2010 4:18 PM
To: Ed Wilts
Cc: veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Destaging going slow
Ed,
Did
you ever heard of NBU users who actually got heir speeds up to acceptable
levels with DSSU ? I asked the same question this morning to NBU support
but I’m pretty sure I already know what the answer will be.
Best
Regards,
Bart
WALLEBROEK
Backup
Admin & Systems & Applications Management & Support
Specialist
Enterprise
Applications Delivery - Infrastructure Management
From: Ed Wilts [mailto:ewilts AT ewilts DOT org]
Sent: Wednesday, June 23, 2010 5:23 PM
To: WALLEBROEK Bart
Cc: veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Destaging going slow
On Wed, Jun 23, 2010 at 8:22 AM, WALLEBROEK
Bart <Bart.WALLEBROEK AT swift DOT com>
wrote:
We have a couple of windows (dedicated) Media
Servers that act as NetBackup DSSU (Disk Staging Storage Unit) servers with
each having from 4 to 16 TB of SAN disks. Backing up to them is no issue
and goes up to the limit of the network connected clients. Destaging to
tape (LTO4) however is slow (20 - 35 MB/sec).
We have been in contact with Symantec where they advised us to lower the
fragment size, change the data buffers size and numbers but we seem to get
stuck to the current speed. Backing up data from this DSSU disk to the
tape drives goes up to physical tape speed limitation.
Does anyone have an idea where to look further to get to a reasonable speed ?
We currently are testing a Solaris DSSU server but we do not have numbers for
that one.
We had this same issue escalated within Symantec and never did find the
problem. We had no such restrictions writing from the media servers
directly to the tape drives, even when going from the DSSU locations - i.e. dd
went at full speed but a destage would go slow. reading the same file that dd read.
We're also mostly Solaris but our Windows media server also saw the same
performance degradation.
We're located close to the NBU developers so we had NetBackup engineers on site
doing investigating and benchmarking. We duplicated the problems for them
but they were unable to find any issues with the destaging code.
We eventually gave up on using DSSUs for the majority of our backups because
the performance hit was unacceptable. If you find a solution, I'd really,
really like to hear about it.
.../Ed
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- Re: [Veritas-bu] Destaging going slow, (continued)
- Re: [Veritas-bu] Destaging going slow, Mark Phillips
- Re: [Veritas-bu] Destaging going slow, Martin, Jonathan
- Re: [Veritas-bu] Destaging going slow, Ed Wilts
- Re: [Veritas-bu] Destaging going slow, Lightner, Jeff
- Re: [Veritas-bu] Destaging going slow, Martin, Jonathan
- Re: [Veritas-bu] Destaging going slow, Lightner, Jeff
- Re: [Veritas-bu] Destaging going slow, Martin, Jonathan
Re: [Veritas-bu] Destaging going slow, Ed Wilts
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