Re: Raid6 write performance

[Peter Rabbitson <rabbit+list@rabbit.us>]

Keld Jørn Simonsen wrote:
> On Mon, Jan 19, 2009 at 03:10:01AM -0500, thomas62186218@aol.com wrote:
>> I tested RAID 5 and RAID 6 with 12 x 15K SAS drives on Ubuntu 8.04 
>> 64-bit and found their performance to be about the same. I used 256 K 
>> chunk size, v1.0 superblocks, stripecachesize of 16384, and readahead 
>> of 65536.
>>
>> RAID 5 reads: 774 MB/sec
>> RAID 5 writes: 585 MB/sec
>>
>> RAID 6 reads: 742 MB/sec
>> RAID 6 writes: 559 MB/sec
>>
>> My CPU utilization remains under 10% though during writes, and I'm 
>> wondering what can be done to get write performance closer to read 
>> performance. I have dual quad-core CPUs so there's plenty of CPU to go 
>> around. Any ideas on that front?
> 
> Seems like it is the same equipment that you also did the raid10,f2
> tests for. I think it would be interesting to have a consolidated list
> of performance comparisons, when you have completed your tweakings.
> Is that part of your plan?
> 
> best regards
> keld

Not on this machine, but yes, I am planning to do something like this on
my workstation. I need to get my drives/arrays in order first (got
bitten by the 7200.11 fiasco).
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