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

On Aug 17, 2011, at 3:56 PM, ktm(at)rice(dot)edu wrote:

> On Wed, Aug 17, 2011 at 03:40:03PM -0500, Ogden wrote:
>>
>> On Aug 17, 2011, at 1:35 PM, ktm(at)rice(dot)edu wrote:
>>
>>> On Wed, Aug 17, 2011 at 01:32:41PM -0500, Ogden wrote:
>>>>
>>>> On Aug 17, 2011, at 1:31 PM, ktm(at)rice(dot)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 configured with RAID 10. The drives are the same (SAS 15K). I tried the new system with ext3 and then XFS but the results seem 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 one with 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.
>>
>>
>> i tested ext4 and the results did not seem to be that close to XFS. Especially when looking at the Block K/sec for the Sequential Output.
>>
>> http://malekkoheavyindustry.com/benchmark.html
>>
>> So XFS would be best in this case?
>>
>> Thank you
>>
>> Ogden
>
> It appears so for at least the Bonnie++ benchmark. I would really try to benchmark
> your actual DB on both EXT4 and XFS because some of the comparative benchmarks between
> the two give the win to EXT4 for INSERT/UPDATE database usage with PostgreSQL. Only
> your application will know for sure....:)
>
> Ken

What are some good methods that one can use to benchmark PostgreSQL under heavy loads? Ie. to emulate heavy writes? Are there any existing scripts and what not?

Thank you

Afra