Re: Filesystem benchmarking for pg 8.3.3 server - Mailing list pgsql-performance
From | Henrik |
---|---|
Subject | Re: Filesystem benchmarking for pg 8.3.3 server |
Date | |
Msg-id | 90A23365-4FD6-414F-8F73-F5BC7BE4AC07@mac.se Whole thread Raw |
In response to | Re: Filesystem benchmarking for pg 8.3.3 server ("Mark Wong" <markwkm@gmail.com>) |
List | pgsql-performance |
8 aug 2008 kl. 18.44 skrev Mark Wong: > On Fri, Aug 8, 2008 at 8:08 AM, Henrik <henke@mac.se> wrote: >> But random writes should be faster on a RAID10 as it doesn't need to >> calculate parity. That is why people suggest RAID 10 for datases, >> correct? >> I can understand that RAID5 can be faster with sequential writes. > > There is some data here that does not support that RAID5 can be faster > than RAID10 for sequential writes: > > http://wiki.postgresql.org/wiki/HP_ProLiant_DL380_G5_Tuning_Guide I'm amazed by the big difference on hardware vs software raid. I set up e new Dell(!) system against a MD1000 DAS with singel quad core 2,33 Ghz, 16GB RAM and Perc/6E raid controllers with 512MB BBU. I set up a RAID 10 on 4 15K SAS disks. I ran IOZone against this partition with ext2 filesystem and got the following results. safeuser@safecube04:/$ iozone -e -i0 -i1 -i2 -i8 -t1 -s 1000m -r 8k - +u -F /database/iotest Iozone: Performance Test of File I/O Version $Revision: 3.279 $ Compiled for 64 bit mode. Build: linux Children see throughput for 1 initial writers = 254561.23 KB/sec Parent sees throughput for 1 initial writers = 253935.07 KB/sec Min throughput per process = 254561.23 KB/sec Max throughput per process = 254561.23 KB/sec Avg throughput per process = 254561.23 KB/sec Min xfer = 1024000.00 KB CPU Utilization: Wall time 4.023 CPU time 0.740 CPU utilization 18.40 % Children see throughput for 1 rewriters = 259640.61 KB/sec Parent sees throughput for 1 rewriters = 259351.20 KB/sec Min throughput per process = 259640.61 KB/sec Max throughput per process = 259640.61 KB/sec Avg throughput per process = 259640.61 KB/sec Min xfer = 1024000.00 KB CPU utilization: Wall time 3.944 CPU time 0.460 CPU utilization 11.66 % Children see throughput for 1 readers = 2931030.50 KB/sec Parent sees throughput for 1 readers = 2877172.20 KB/sec Min throughput per process = 2931030.50 KB/sec Max throughput per process = 2931030.50 KB/sec Avg throughput per process = 2931030.50 KB/sec Min xfer = 1024000.00 KB CPU utilization: Wall time 0.349 CPU time 0.340 CPU utilization 97.32 % Children see throughput for 1 random readers = 2534182.50 KB/sec Parent sees throughput for 1 random readers = 2465408.13 KB/sec Min throughput per process = 2534182.50 KB/sec Max throughput per process = 2534182.50 KB/sec Avg throughput per process = 2534182.50 KB/sec Min xfer = 1024000.00 KB CPU utilization: Wall time 0.404 CPU time 0.400 CPU utilization 98.99 % Children see throughput for 1 random writers = 68816.25 KB/sec Parent sees throughput for 1 random writers = 68767.90 KB/sec Min throughput per process = 68816.25 KB/sec Max throughput per process = 68816.25 KB/sec Avg throughput per process = 68816.25 KB/sec Min xfer = 1024000.00 KB CPU utilization: Wall time 14.880 CPU time 0.520 CPU utilization 3.49 % So compared to the HP 8000 benchmarks this setup is even better than the software raid. But I'm skeptical of iozones results as when I run the same test agains 6 standard SATA drives in RAID5 I got random writes of 170MB / sek (!). Sure 2 more spindles but still. Cheers, Henke
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