Re: Slow write performance with mpt2sas

[Wakko Warner]

Wakko Warner wrote:
> I've noticed that my SAS9212-4i4e is having write issues.  I have a raid5 of
> 4 2tb seagate green drives and a raid5 of 3 300gb seagate 15k sas drives. 
> Write performance on the green drives is fairly poor.  The riad4 of 4 disks
> has a write performance of about 6-10mb/sec.  My onboard sas controller
> (1068e chip IT mode) does not have this issue (I'm using raid6 on 8 of the
> same model green drives).
> 
> Write performance on the 15k drives in raid 5 was 140mb/sec (4gb volume).

Sorry, this appears to be a KVM issue.  I had forgotten that I was using
this under KVM.  Adding cache=writeback fixed my problems (Also note, my
load before this went to >35 when writing, now it's no higher than about 9)
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