topic Re: RAID 10 on HP SmartArray 6i in Disk Enclosures

RAID 10 on HP SmartArray 6i

MidRange Support — Mon, 11 Dec 2006 16:35:09 GMT

Can someone confirm the following behavior is correct on the following configuration?

HP DL380-G4
Xeon 3.6Ghz x 2CPUs
8GB RAM
6 int HP 15K SCSI HDs
- 2 x 36GB HDs in RAID1 for OS
- 4 x 146GB HDs in RAID10 for Transactn Logs

MSA30 enclos. connected to 2 seperate HP6400s
7 x 146GB HDs in RAID10 w/1 hotspare on 1 channel to 1st HP6400EM controller
7 x 146GB HDs in RAID10 w/1 hotspare on 1 channel to 2nd HP6400EM controller

Please confirm that sequential reads from either RAID10 array on the MSA30 will use all 6 spindles in the respective array and not just read from 3 spindles. My understanding is that RAID1 mirrors will utilize both sides of the mirror for sequential reads thereby increasing read throughput. I understood that RAID10 arrays get the same benefit during sequential reads.

Please confirm and explain why this IS or is NOT true. Thanks.

Re: RAID 10 on HP SmartArray 6i

Jefferson Humber — Tue, 12 Dec 2006 06:25:11 GMT

"My understanding is that RAID1 mirrors will utilize both sides of the mirror for sequential reads thereby increasing read throughput."

Hmmm, not sure. I did hear once that the read can come entirely from one spindle. Depending on the head position of the disk, it may be quicker for all the IO's to come from just one of the mirrors.

Re: RAID 10 on HP SmartArray 6i

MidRange Support — Tue, 12 Dec 2006 16:20:10 GMT

Thanks for the response. Could you provide any documentation that states that the standard RAID10 specification includes multiplexed/load balanced reads across both sides of the mirrror during sequential read operations? I've not been able to find anything that states this equivocally.

Any documentation from a manufacturer or standards body will serve my purposes. If not then any type of whitepaper or benchmarking study would also work well.

Thanks for any leads or information you can provide.

Shaun.