Re: High CPU Utilization

On 3/24/09 4:16 PM, "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com> wrote:

> On Tue, Mar 24, 2009 at 4:58 PM, Ron <rjpeace(at)earthlink(dot)net> wrote:
>> At 02:47 PM 3/24/2009, Joe Uhl wrote:
>>
>>> Turns out we may have an opportunity to purchase a new database server
>>> with this increased load.  Seems that the best route, based on feedback to
>>> this thread, is to go whitebox, get quad opterons, and get a very good disk
>>> controller.
>>>
>>> Can anyone recommend a whitebox vendor?
>>
>> I'll 2nd the Aberdeen recommendation.  I'll add Pogolinux to that list as
>> well.
>>
>>
>>> Is there a current controller anyone on this list has experience with that
>>> they could recommend?
>>
>> The 2 best performing RAID controller vendors at this time are AMCC (AKA
>> 3Ware) and Areca.
>> In general, the 8+ port Areca's with their BB cache maxed outperform every
>> other controller available.

I personally have had rather bad performance experiences with 3Ware
9550/9650 SATA cards. I have no experience with the AMCC SAS stuff though.
Adaptec demolished the 9650 on arrays larger than 4 drives, and Areca will
do better at the very high end.

However, if CPU is the issue for this particular case, then the RAID
controller details are less significant.

I don't know how much data you have, but don't forget the option of SSDs, or
a mix of hard drives and SSDs for different data. Ideally, you would want
the OS to just extend its pagecache onto a SSD, but only OpenSolaris can do
that right now and it is rather new (needs to be persistent across reboots).

http://blogs.sun.com/brendan/entry/test
http://blogs.sun.com/brendan/entry/l2arc_screenshots

>>
>>
>>> This will be a bigger purchase so will be doing research and benchmarking
>>> but any general pointers to a vendor/controller greatly appreciated.
>>
>> Be =very= careful to thoroughly bench both the AMD and Intel CPU options.
>>  It is far from clear which is the better purchase.
>
> My anecdotal experience has been that the Opterons stay afloat longer
> as load increases, but I haven't had machines with similar enough
> hardware to really test that.
>

One may want to note that Intel's next generation servers are due out within
45 days from what I can sense ('Q2' traditionally means ~April 1 for Intel
when on time). These should be a rather significant bump for a database as
they adopt the AMD / Alpha style memory-controller-on-CPU architecture and
add a lot of cache. Other relevant improvements: increased performance on
compare-and-swap operations, the return of hyper threading, and ridiculous
memory bandwidth per CPU (3 DDR3 memory channels per CPU).

>> I'd be very interested to see the results of your research and benchmarks
>> posted here on pgsql-performance.
>
> Me too. I'm gonna spend some time this summer benchmarking and tuning
> the database servers that I pretty much had to burn in and put in
> production this year due to time pressures.
>
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