[CentOS] which kernel do people use?

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On 10/25/2013 04:38 AM, Nicolas Thierry-Mieg wrote:
> interesting datapoint for HDD vs SSD, but what about kernel versions? 
> When using SSDs, did you need to use 3.8+ kernels as suggested in the 
> quoted post, or do you use stock? thanks

I've taken some flack for being off-topic regards my comments on SSDs, 
though it would seem relevant to know that we're using Stock CentOS 
kernel, and that we aren't using trim because the performance increase 
was so much improved over spinning disks that we didn't seem to need it. 
Our use case is a worst-case read/write scenario. The SSD partitions we 
use for the DB servers are mirrored software RAID1, which, to my 
understanding, makes the use of trim impossible.

Where we've had performance problems we've always found something else 
to be the bottle neck, typically a poorly constructed query. (PostgreSQL 
really, REALLY hates left outer joins)

It's possible that we could eek out more performance with a suggested 
kernel update. If/when we do performance testing on that front, I'll 
make it a point to submit my results.