Re: Two identical systems, radically different performance

On Oct 9, 2012, at 2:06 AM, Craig James <cjames(at)emolecules(dot)com> wrote:

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> On Mon, Oct 8, 2012 at 2:57 PM, Evgeny Shishkin <itparanoia(at)gmail(dot)com> wrote:
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> On Oct 9, 2012, at 1:45 AM, Craig James <cjames(at)emolecules(dot)com> wrote:
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>> I tested both the RAID10 data disk and the RAID1 xlog disk with bonnie++. The xlog disks were almost identical in performance. The RAID10 pg-data disks looked like this:
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>> Old server:
>> Version 1.96 ------Sequential Output------ --Sequential Input- --Random-
>> Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
>> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
>> xenon 24064M 687 99 203098 26 81904 16 3889 96 403747 31 737.6 31
>> Latency 20512us 469ms 394ms 21402us 396ms 112ms
>> Version 1.96 ------Sequential Create------ --------Random Create--------
>> xenon -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
>> files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
>> 16 15953 27 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
>> Latency 43291us 857us 519us 1588us 37us 178us
>> 1.96,1.96,xenon,1,1349726125,24064M,,687,99,203098,26,81904,16,3889,96,403747,31,737.6,31,16,,,,,15953,27,+++++,+++,+++++,++\
>> +,+++++,+++,+++++,+++,+++++,+++,20512us,469ms,394ms,21402us,396ms,112ms,43291us,857us,519us,1588us,37us,178us
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>> New server:
>> Version 1.96 ------Sequential Output------ --Sequential Input- --Random-
>> Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
>> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
>> zinc 24064M 862 99 212143 54 96008 14 4921 99 279239 17 752.0 23
>> Latency 15613us 598ms 597ms 2764us 398ms 215ms
>> Version 1.96 ------Sequential Create------ --------Random Create--------
>> zinc -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
>> files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
>> 16 20380 26 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
>> Latency 487us 627us 407us 972us 29us 262us
>> 1.96,1.96,zinc,1,1349722017,24064M,,862,99,212143,54,96008,14,4921,99,279239,17,752.0,23,16,,,,,20380,26,+++++,+++,+++++,+++\
>> ,+++++,+++,+++++,+++,+++++,+++,15613us,598ms,597ms,2764us,398ms,215ms,487us,627us,407us,972us,29us,262us
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> Sequential Input on the new one is 279MB/s, on the old 400MB/s.
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> But why? What have I overlooked?

blockdev --setra 32000 ?
Also you benchmarked volume for pgdata? Can you provide benchmarks for wal volume?
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> Thanks,
> Craig
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