RAID Performance

[paraffin]

Hello Everyone

I have a question regarding the best disk configuration and my question is

Do 8 disks in RAID 5 perform better than 8 disks in RAID 1+0? The disks used are HP 146GB 2.5" 15k 6G

We obviously get more disk space in RAID5 but is this at a cost to write performance in this configuration?

I will be running 2 sizeable databases (60GB) on these disks as well as the up to 8 Windows 2003 R2 VM's so write performance is important.

Thanks in advance

David

[a_p_]

David,

in this case I would suggest you go with RAID 10 and/or several RAID1 groups.

With an additional datastore on RAID1 you can separate DB data and logs.

Important for performance: Make sure you have battery buffered write cache for your RAID controller!!

André

[jfelinski]

With raid 10 you'll get a better write performance. It is related to "write penalty" factor of different raid characteristics.

To keep it simple assuming that one 15k drive will have around 150 IOPS, you'll get the following

RAID 5 - 1200IOPS on 100% read - 300 IOPS on 100% write (write penalty 4)

RAID 10 - 1200IOPS on 100% read - 600 IOPS on 100%write (write penalty 2)

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MCSA+S, VCP 3, VCP 4

[paraffin]

OK I am confused with RAID now which I wasn't before...

So an 8 disk RAID5 has the same read performance as an 8 disk RAID10 i.e 4 mirrored pairs, I would of expected RAID10 to only be reading from 4 drives.

Am I incorrect?