On Oct 19, 2010, at 11:22 AM, Bruce Momjian wrote: > Greg Smith wrote: >> A.M. wrote: >>> Perhaps a simpler tool could run a basic fsyncs-per-second test and prompt >>> the DBA to check that the numbers are within the realm of possibility. >>> >> >> This is what the test_fsync utility that already ships with the database >> should be useful for. The way Bruce changed it to report numbers in >> commits/second for 9.0 makes it a lot easier to use for this purpose >> than it used to be. I think there's still some additional improvements >> that could be made there, but it's a tricky test to run accurately. The > > test_fsync was designed to test various things like whether several > open-sync writes are better than two write and an fsync, and whether you > can fsync data written on a different file descriptor. It is really a > catch-all test right now, not one specific for choosing sync methods.
I am working on simplifying the test_fsync tool and making it a contrib function which can be run by the superuser based on the configured fsync method. That way, the list can ask a user to run it to report fsyncs-per-second for suspiciousness. The goal is to make it more accessible. I was also thinking about adding some notes along the lines of "Your drive fsync speed rates between a 5400 RPM SATA drive and a 7200 RPM SATA drive." or "Your drive fsync speed rates as high as RAM- your fsync method may be wrong." Currently, the test tool is not even compiled by default. Thoughts? Cheers, M -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
