I'm curious about NUMBER_DATA_BUFFERS_RESTORE and duplication performance as well. Anybody know this definitively?
________________________________ From: [EMAIL PROTECTED] on behalf of Peters, Devon C Sent: Tue 11/20/2007 1:32 PM To: VERITAS-BU@mailman.eng.auburn.edu Subject: Re: [Veritas-bu] T2000 vaulting performance with VTL/LTO3 Chris, To me it looks like there's a 1Gb bottleneck somewhere (90MB/s is about all we ever got out of 1Gb fibre back in the day). Are there any ISL's between your tape drive, your switch, and your server's HBA? Also, have you verified that your tape drives have negotiated onto the fabric as 2Gb and not 1Gb? When we had 2Gb LTO-3 drives on our T2000's, throughput to a single drive toped out around 160MB/s. When we upgraded the drives to 4Gb LTO-3, throughput to a single drive went up to 260MB/s. Our data is very compressible, and these numbers are what I assume to be the limitation of the IBM tape drives. Regarding buffer settings, my experience may not apply directly since we're doing disk (filesystems on fast storge) to tape backups, rather than VTL to tape. With our setup we see the best performance with a buffer size of 1048576 and 512 buffers. For us these buffer sizes are mostly related to the filesystem performance, since we get better disk throughput with 1MB I/O's than with smaller ones... I'm also curious if anyone knows whether the NUMBER_DATA_BUFFERS_RESTORE parameter is used when doing duplications? I would assume it is, but I don't know for sure. If it is, then the bptm process reading from the VTL would be using the default 16 (?) buffers, and you might see better performance by using a larger number. -devon ------------------------------------- Date: Fri, 16 Nov 2007 10:00:18 -0800 From: Chris_Millet <[EMAIL PROTECTED]> Subject: [Veritas-bu] T2000 vaulting performance with VTL/LTO3 To: VERITAS-BU@mailman.eng.auburn.edu Message-ID: <[EMAIL PROTECTED]> I'm starting to experiment with the use of T2000 for media servers. The backup server is a T2000 8 core, 18GB system. There is a Qlogic QLE2462 PCI-E dual port 4Gb adapter in the system that plugs into a Qlogic 5602 switch. From there, one port is zoned to a EMC CDL 4400 (VTL) and a few HP LTO3 tape drives. The connectivity is 4Gb from host to switch, and from switch to the VTL. The tape drive is 2Gb. So when using Netbackup Vault to copy a backup done to the VTL to a real tape drive, the backup performance tops out at about 90MB/sec. If I spin up two jobs to two tape drives, they both go about 45MB/sec. It seems I've hit a 90MB/sec bottleneck somehow. I have v240s performing better! Write performance to the VTL from incoming client backups over the WAN exceeds the vault performance. My next step is to zone the tape drives on one of the HBA ports, and the VTL zoned on the other port. I'm using: SIZE_DATA_BUFFERS = 262144 NUMBER_DATA_BUFFERS = 64 Any other suggestions?
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