I have raised this with CommVault support twice and with PS resources to try and get some assistance; no major progress.
With the Aux copy performance I am doing cross-site with several different storage policies, so I don't really have the option of running more than one device stream for each aux copy (and that would only be hiding the real issue anyway).
Here's something interesting:
I actually cut a backup over on the weekend from network to SAN attached tape (client as media agent for itself). Linux box - 5TB of user data with lots of files. The backup ran the previous weekend over the network (1Gb) to a dedicated windows MA < at > 320GB/hr (1.1:1 software compression). After cutting over to FC attached tape direct I get 250GB/hr! 4 readers used for both backups. I am guessing this has to do with the stream of compressed data being sent with client side compression and/or how the buffering happens on the media agent.
JJ
--- In commvault < at > yahoogroups.com ([email]commvault%40yahoogroups.com[/email]), George Haddad <georgeh < at > ...> wrote:
I've been trying everything to improve throughput. I've been
experimenting with different multiplex factors, different chunksizes,
and for AUxes I've enabled stream randomization. I've re-configged the
Qlogic 2462s per some (rather dated) IBM Redbook settings. I have seen
improved performance at times, but cannot sustain it regularly. Looking
at the actual throughput to the Tape Drives I've seen as high as 85-100
MB/sec. I'd be happy to get that regularly. But that's when the
Commserve and Media Agents involved are otherwise idle. Mostly I see
20-50MB/sec ... but at times as low as 1-5MB/sec. Usually the 1-5 is
when the Commserve and MAs are going full-tilt with primary disk copies
while simumultaneously running AUXes to tape. Maybe that's the best I
can expect under those circumstances? One thing I've noticed is that
tape throughput usually falls off when a single MA is writing to more
than 1 tape. We have tapes distributed across 2 HBA ports (via separate
switches). But Commvault will often allocate 2 drives on the same HBA. I
don't know if splitting the tapes into different pools would help.
William Morris wrote:
JJ
You are doing better than we are. DELL PB 2950 Win 2003 R < at > Comcell.
Dell ML600 Library with LT04. Max
I have ever rec'd is 280 mb/hr and that's an AUX copy..
Bill
*From:* commvault < at > yahoogroups.com ([email]commvault%40yahoogroups.com[/email]) [mailto:commvault < at > yahoogroups.com ([email]commvault%40yahoogroups.com[/email])]
*On Behalf Of *J J
*Sent:* Wednesday, February 03, 2010 10:34 PM
*To:* commvault < at > yahoogroups.com ([email]commvault%40yahoogroups.com[/email])
*Subject:* [SPAM] [commvault] LTO4 Performance Recommendations -
backup, restore, and aux copies
Hi,
Anyone out there driving LTO4 tape drives in anger with CommVault? We
are v8 SP4. HP ESL tape libraries with HP LTO4 FC drives.
I am struggling to get the performance I am expecting (I got almost
500GB/hr to a single LTO4 drive with h/w compression and 8 concurrency
a.k.a multiplexing out of our old HP DataProtector software).
CommVault Backup to tape, h/w compression only, large file backup
(database flat file snapshot) - maximum throughput I get is about
375GB/hr with 8xreaders, 8 Multiplexing to one drive, 16G chunk size,
256K block size (the client/media agent in question - 6xCPU 16G Mem
HPUX server doing nothing but this backup). TapeTool or similar can
push to the 410GB/hr approx theoretical limit with compression off, so
I know the infrastructure is capable.
Even though I would class this backup performance as "adequate" for
LTO4, I am worried about the implications of such a configuration on
our restore times. If multiplexing is reduced, we don't get much more
than low 200's (GB/hr).
Tape-to-Tape aux copies are also terrible performance - about 200GB/hr
max. I expect these should flow through at close to double that (near
raw speed limit of LTO4), as if I understand it correctly a
synchronous aux copy is purely reading and writing chunks of data and
should be able to get the tapes streaming+screaming.
Anyone have any experience with this? Helpful tips particularly on
speeding up the Aux copies? Achieved throughputs/speeds that I could
use as a comparison?
Any help on performance recommendations/own in-house tuning around
items such as: tape block size, chunk size, multiplexing factor,
CommVault memory buffering registry settings etc?
The slow aux copies are killing us as we do cross-site tape copies and
after a weekend's full backups we are running the cross-site tape copy
for a couple of days.
Thanks!
J
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