Re: IDE Drives and fsync

"scott.marlowe" <scott(dot)marlowe(at)ihs(dot)com> writes:
> Tom, you had mentioned adding a delay of some kind to the fsync logic, and
> I'd be more than willing to try out any patch you'd like to toss out to me
> to see if we can get a semi-stable behaviour out of IDE drives with the
> -W1 and -f switches turned on.

I'd suggest experimenting with the delay in mdsync() in
src/backend/storage/smgr/md.c. A larger delay should theoretically make
things more reliable.

If you see signs of corruption of the WAL itself, another knob you could
fool with is the wal_sync_method setting in postgresql.conf. I have no
idea whether different sync methods would improve the odds of getting
the drive to write WAL sectors in the right order, but it'd be worth
experimenting with.

I dunno whether you have the ability to experiment with a dual-drive
machine, but it would certainly be worth revisiting all these tests
on a setup with WAL on a separate drive.

regards, tom lane