Re: Raid over 48 disks

[Bill Davidsen <davidsen@tmr.com>]

Thiemo Nagel wrote:
> Bill Davidsen wrote:
>>>     16k read    64k write
>>>   chunk
>>>   size    RAID 5    RAID 6    RAID 5    RAID 6
>>>   128k    492    497    268    270
>>>   256k    615    530    288    270
>>>   512k    625    607    230    174
>>>   1024k   650    620    170    75
>>>   
>>
>> What is your stripe cache size?
>
> I didn't fiddle with the default when I did these tests.
>
> Now (with 256k chunk size) I had
>
> # cat stripe_cache_size
> 256
>
> but increasing that to 1024 didn't show a noticeable improvement for 
> reading.  Still around 550MB/s.

You can use blockdev to raise the readahead, either on the drives or the 
array. That may make a difference, I use 4-8MB on the drive, more on the 
array depending on how I use it.
>
> Kind regards,
>
> Thiemo
>


-- 
Bill Davidsen <davidsen@tmr.com>
  "Woe unto the statesman who makes war without a reason that will still
  be valid when the war is over..." Otto von Bismark