[CentOS] mdraid on top of mdraid

John R Pierce pierce at hogranch.com
Tue Mar 22 04:24:10 UTC 2011

On 03/21/11 9:11 PM, Emmanuel Noobadmin wrote:
>> You'll have really poor
>> performance if you raid over iscsi...
> I've spent more time thinking about this and reading over my
> research.The crux here seems to be that while RAID does impose
> additional write IOPS costs, it may be more than offset by the read
> advantage. According to my own notes (which I overlooked in my first
> reply), the increased performance from scaling was part of the
> original reason I was thinking of using RAID on top of iSCSI.
> Searching more on this, the consensus seems to be that RAID 1/10 on
> iSCSI is quite okay and may provide read performance increase but RAID
> 5's iops penalty will probably be a killer.

if you can use 2 dedicated ethernet adapters to 2 iSCSI servers  for 
this mirror, its probably a win.

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