Using a RAID adapter with Tape Hardware

Question

Hi guys, Can anyone point to any hard evidence or studies that a RAID capable HBA cannot/should not be used with tape hardware? I was always of the opinion, and real world experience backs this up, that doing this is a bad idea even if you somehow manage to get it working. However, it seems that, for HP at least, nearly all of their SAS HBA's have RAID functions, and we are continually having our local hardware vendors suggest the HP P212 SmartArray adapter in particular. I've always recommended use of a 'plain' HBA, in this case the HP SC44Ge but for whatever reason this adapter is not supported on HP's G6/G7 servers, the P212 is being suggested in its place. So that brings me back to my first point, regardless of what HP thinks, is it now acceptable in the industry to plug tape hardware into a RAID adapter? Or perhaps this is more of an issue with SCSI than it is with SAS? Any opinions welcome, John.

coganb · Accepted Answer

Hi John,

I sent you this by email. I post here for the benefit of the forum:

I have created the following knowledgebase article which covers EMC's recommendations on this.

esg121112 - Does EMC support NetWorker configurations where the tape hardware is attached to a HBA (either SCSI or SAS) which is a RAID adapter?

-Bobby

Mark_Bellows · Answer

It has been my experience that a RAID controller is not the recommended device for connection to a tape drive. RAID controllers are designed to run disks which random access (read write) devices. Tape drives, on the other hand, are sequential devices and write from beginning to end and usually read in the same fashion.

If you are having issue or poor performance using a RAID controler, I would strongly recommend that you use a standard SCSI / HBA connection designed for tape drives.

Mark

NetWorker

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