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Typical fibre channel tape library backup speeds?

Jeff Cashmore
Occasional Visitor

Typical fibre channel tape library backup speeds?

I've got the FC library backup system working but it's slow. The system consists of the following...

Compaq MSL5052S2FC (50 slots) with built in NSR E1200 (FC to SCSI card) and 2 SDLT2 drives
Compaq StorageWorks SAN switch 2/16-EL
Compaq StorageWorks FCA2101 2Gbps cards in the servers

Installed Arcserve 2000 V7 (SP3), OFO, TLO, & SAN options on 8 Win2000 (SP3) servers, ran SAN cfg and setup one primary and 7 distributed servers. Configured index map and changed performance mode on E1200 to 2 Gbps, (default is 1 Gbps). The system works but we're showing backup speeds of around 200 MB/min in Arcserve. Since the clients old directly connected DLT jobs ran at 120 MB/min he's less than impressed. CA's E-Trust anti-virus SW is set to scan incoming files only. Does anyone have a suggestion as to gaining more performance? I did find the following page at HP's web site and will try a couple of hints.

date: 2/21/03
document description: HP StorageWorks - Performance Troubleshooting and Using Performance Assessment Tools
document id: lpg50460

Leif Halvarsson_2
Honored Contributor

Re: Typical fibre channel tape library backup speeds?

I have a similar configuration in our test enviroment, MSL 5030, E1200, Qlogic SANBox 8 (2GB) and Qlogic 2300 (2GB). The backup program is DataProtector 5.0.

If the clients is fast enough (disk systems,CPU) it is no problem to reach full speed for the drive (30MB/s, hardware compression on).

Does Archserve support changing blocksize for the drive. Check what blocksize is used, I dont know recommendations for SDLT drives but for LTO you must use at least 32 or better 64kB to reach full performance.

Also, check your disk system, if the disk system can't deliver data fast enough you will never reach the full performance of your drives.
Chris Vail
Honored Contributor

Re: Typical fibre channel tape library backup speeds?

My experience with this has been using Netbackup under Unix, but there is one thing in common: the f/c to SCSI bridge. I despise the things: they're slow and unreliable.

We also have speed problems, but our server is horribly undersized. It only has (4) 440Mhz processors, and a single backplane. Our bottleneck is a combination of the server itself and the fiber/scsi muxes. We have 12 StorageTek 9940a drives in an L700 cabinet. We can get the full rated speed out of them (36GB/hour/tape) only if we don't use all 12--the server just can't keep the light pipes filled with that much data.

Why don't you look into the performance of the servers themselves while they're making their backups. The problem you're having may be that the servers themselves can't fill their pipes up--like ours.

Glenn Weavind_1
Frequent Advisor

Re: Typical fibre channel tape library backup speeds?

Jeff: Unless I'm mistaken your data flow is still from disk, through your backup server and out again - you need the Serverless Option to have data flow from disk directly to the NSR E1200, which should be much faster.
Pretty much all heavyweight backup products use the optimum block size for the tape devices that they've detected - and fiddling with block size can rapidly produce tapes that are unreadable.
Performance tuning backups requires a lot of data collecting and analysis - it's the activity that stresses servers and infrastructure the hardest. What's CPU load like on your backup server? Can you move data from disk to server faster than your backups? If the data flow is as I suspect, you'll be scanning everything inbound to the server - run some backups with A/V disabled as a test.