Re: Two identical systems, radically different performance

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>> TPS including connection establishing, pgbench run in a single
>> thread mode, connection made through unix socket, OS cache dropped
>> and Postgres restarted for every run.
>>
>> those are the results:
>>
>>                 HT        HT SYSFS DIS    HT BIOS DISABLE
>> -c -t     r1   r2   r3    r1   r2   r3    r1   r2   r3
>> 5  20K   1641 1831 1496  2020 1974 2033  2005 1988 1967
>> 10 10K   2161 2134 2136  2277 2252 2216  1854 1824 1810
>> 20 5k    2550 2508 2558  2417 2388 2357  1924 1928 1954
>> 30 3333  2216 2272 2250  2333 2493 2496  1993 2009 2008
>> 40 2.5K  2179 2221 2250  2568 2535 2500  2025 2048 2018
>> 50 2K    2217 2213 2213  2487 2449 2604  2112 2016 2023
>>
>> Despite the fact the results don't match my expectation
>
> You have a RAID1 with 15K SAS disks.  I have a RAID10 with 8 7200 SATA
> disks plus another RAID1 for the XLOG file system.  Ten 7K SATA disks
> on two file systems should be quite a bit faster than two 15K SAS
> disks, right?

I think you're right. But I never have the chance to try such
a configuration in first person. But, yes, spreading I/O on two
different subsystems (xlog and pgdata) and having pgdata on
a RAID10 should surely outperform my RAID1 with 15K SAS disks.

>> (I suspect that there's something wrong with the PERC
>> because, having the controller cache enabled make no
>> difference in terms of TPS), it seems strange that disabling
>> HT from the bios will give lesser TPS that HT disable through
>> sysfs interface.
>
> Well, all I can say is that I like my 3WARE controllers, and it's the
> secondary reason why I moved away from Dell (the primary reason is
> price).

Something I surely will take into account the next time
I will buy a new server.

Andrea