Why is using RAID option no faster then not using it?

[gwichman]

We're reading some older tapes. Some were created with RAID0 tape option (arcserv 2000) with 4 DLT8000 tape drives. The others were not (single tapes). The throughput on restoring the RAID tapes is no better then the single tapes.. This is contrary to what CA claims and that is that you should see a performance increase.

Any ideas or does anyone have any experiences that can vouch for the fact that indeed it should be faster?

 

[jabus]

Is it possible that the restore destination is the bottleneck, not the tape drives? Does it have sufficient write-back cache enabled?

 

[gwichman]

I don't know what write back cache is. Is that on the client or server side? Something you tune in arcserve, the exhange agent, or OS itself? Actually we're restoring exchange (agent) from/to the same server. I.e. arcserv and exchange are installed on the same machine. The server is plenty fast though and not showing much of a load in any sense (ram/cpu/disk/network)