Re: hardware upgrade, performance degrade?

On Mon, Mar 4, 2013 at 4:17 PM, John Rouillard <rouilj(at)renesys(dot)com> wrote:
> On Mon, Mar 04, 2013 at 03:54:40PM -0700, Steven Crandell wrote:
>> Here's our hardware break down.
>>
>> The logvg on the new hardware is 30MB/s slower (170 MB/s vs 200 MB/s )
>> than the logvg on the older hardware which was an immediately interesting
>> difference but we have yet to be able to create a test scenario that
>> successfully implicates this slower log speed in our problems. That is
>> something we are actively working on.
>>
>>
>> Old server hardware:
>> Manufacturer: Dell Inc.
>> Product Name: PowerEdge R810
>> 4x Intel(R) Xeon(R) CPU E7540 @ 2.00GHz
>> 32x16384 MB 1066 MHz DDR3
>> Controller 0: PERC H700 - 2 disk RAID-1 278.88 GB rootvg
>> Controller 1: PERC H800 - 18 disk RAID-6 2,178.00 GB datavg, 4
>> drive RAID-10 272.25 GB logvg, 2 hot spare
>> 2x 278.88 GB 15K SAS on controller 0
>> 24x 136.13 GB 15K SAS on controller 1
>>
>> New server hardware:
>> Manufacturer: Dell Inc.
>> Product Name: PowerEdge R820
>> 4x Intel(R) Xeon(R) CPU E5-4620 0 @ 2.20GHz
>> 32x32 GB 1333 MHz DDR3
>> Controller 0: PERC H710P - 4 disk RAID-6 557.75 GB rootvg
>> Controller 1: PERC H810 - 20 disk RAID-60 4,462.00 GB datavg, 2
>> disk RAID-1 278.88 GB logvg, 2 hot spare
>> 28x278.88 GB 15K SAS drives total.
>
> Hmm, you went from a striped (raid 1/0) log volume on the old hardware
> to a non-striped (raid 1) volume on the new hardware. That could
> explain the speed drop. Are the disks the same speed for the two
> systems?

Yeah that's a terrible tradeoff there. Just throw 4 disks in a
RAID-10 instead of RAID-60. With 4 disks you'll get the same storage
and much better performance from RAID-10.

Also consider using larger drives and a RAID-10 for your big drive
array. RAID-6 or RAID-60 is notoriously slow for databases,
especially for random access.