Re: Raid 5 vs Raid 10 Benchmarks Using bonnie++

On 8/17/2011 1:35 PM, ktm@rice.edu wrote:
> On Wed, Aug 17, 2011 at 01:32:41PM -0500, Ogden wrote:
>>
>> On Aug 17, 2011, at 1:31 PM, ktm@rice.edu wrote:
>>
>>> On Wed, Aug 17, 2011 at 01:26:56PM -0500, Ogden wrote:
>>>> I am using bonnie++ to benchmark our current Postgres system (on RAID 5) with the new one we have, which I have
configuredwith RAID 10. The drives are the same (SAS 15K). I tried the new system with ext3 and then XFS but the
resultsseem really outrageous as compared to the current system, or am I reading things wrong? 
>>>>
>>>> The benchmark results are here:
>>>>
>>>> http://malekkoheavyindustry.com/benchmark.html
>>>>
>>>>
>>>> Thank you
>>>>
>>>> Ogden
>>>
>>> That looks pretty normal to me.
>>>
>>> Ken
>>
>> But such a jump from the current db01 system to this? Over 20 times difference from the current system to the new
onewith XFS. Is that much of a jump normal? 
>>
>> Ogden
>
> Yes, RAID5 is bad for in many ways. XFS is much better than EXT3. You would get similar
> results with EXT4 as well, I suspect, although you did not test that.
>
> Regards,
> Ken
>

A while back I tested ext3 and xfs myself and found xfs performs better
for PG.  However, I also have a photos site with 100K files (split into
a small subset of directories), and xfs sucks bad on it.

So my db is on xfs, and my photos are on ext4.

The numbers between raid5 and raid10 dont really surprise me either.  I
went from 100 Meg/sec to 230 Meg/sec going from 3 disk raid 5 to 4 disk
raid 10.  (I'm, of course, using SATA drives.... with 4 gig of ram...
and 2 cores.  Everyone with more than 8 cores and 64 gig of ram is off
my Christmas list! :-) )

-Andy