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Some more on the RHEL 5.5 system
I'm helping to setup. Some benchmarking using pgbench appeared to
suggest that wal_sync_method=open_sync was a little faster than
fdatasync [1]. Now I recall some discussion about this enabling direct
io and the general flakiness of this on Linux, so is the option
regarded as safe? [1] The workout: $ pgbench -i -s 1000 bench $ pgbench -c [1,2,4,8,32,64,128] -t 10000 Performance peaked around 2500 tps @32 clients using open_sync and 2200 with fdatasync. However the disk arrays are on a SAN and I suspect that when testing with fdatasync later in the day there may have been workload 'leakage' from other hosts hitting the SAN. |
