Re: PSA: If you are running Precise/12.04 upgrade your kernel.

On Fri, Jun 7, 2013 at 5:51 AM, Joshua D. Drake <jd@commandprompt.com> wrote:
>
> On 06/06/2013 03:48 PM, Scott Marlowe wrote:
>>
>>
>> On Thu, Jun 6, 2013 at 4:35 PM, Joshua D. Drake <jd@commandprompt.com>
>> wrote:
>>>
>>> I had the distinct displeasure of staying up entirely too late with a
>>> customer this week because they upgraded to 12.04 and immediately
>>> experienced a huge performance regression. In the process they also
>>> upgraded
>>> to PostgreSQL 9.1 from 8.4. There were a lot of knobs to
>>> change/fix/modify
>>> because of this. However, nothing I did fixed the problem. Until... I
>>> upgraded the kernel.
>>>
>>> Upgrading from 3.2Precise to the 3.9.4 kernel produced the following
>>> results:
>>
>>
>> I've since heard that 3.4 also fixes this issue as well.
>>
>> What are you using for your IO on these boxes?
>
> I was able to demonstrate it over iSCSI to a Nimble Storage SAN as well as
> DAS with 2 drive RAID 1 for xlogs and 8 drive RAID 10 for data (DL385 G7).


This might sound familiar:

http://postgresql.1045698.n5.nabble.com/Ubuntu-12-04-3-2-Kernel-Bad-for-PostgreSQL-Performance-td5735284.html

tl;dr for that thread seems to be a driver problem (fusionIO?), I'm
unsure if Ubuntu specific or in the upstream kernel.

--
Stuart Bishop <stuart@stuartbishop.net>
http://www.stuartbishop.net/