Re: xfs perform a lot better than ext4 [WAS: Re: Two identical systems, radically different performance]

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on this box:

in a brief: the box is dell a PowerEdge r720 with 16GB of RAM,
the cpu is a Xeon 5620 with 6 core, the OS is installed on a raid
(sata disk 7.2k rpm) and the PGDATA is on separate RAID 1 array
(sas 15K rpm) and the controller is a PERC H710 (bbwc with a cache
of 512 MB). (ubuntu 12.04)

on the same machine with the same configuration,
having PGDATA on a xfs formatted partition gives me
a much better TPS.

e.g. pgbench  -c 20 -t 5000 gives me 6305 TPS
(3 runs with "echo 3 > /proc/sys/vm/drop_caches && /etc/init.d/postgresql-9.2 restart"
in between).
Hi, I found this interesting as I'm trying to do some benchmarks on my box which is very similar to the above but I don't believe the tps is any where near what it should be. Is the 6305 figure from xfs? I'm assuming that your main data array is just 2 15k sas drives, are you putting the WAL on the data array or is that stored somewhere else? Can I ask what scaling params, etc you used to build the pgbench tables and look at your postgresql.conf file to see if I missed something (offline if you wish)

I'm running 8x SSDs in RAID 10 for the data and pull just under 10k on a xfs system which is much lower than I'd expect for that setup and isn't significantly greater than your reported results, so something must be very wrong.

Thanks

John


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