Hi, On 2018-02-20 00:27:47 +0000, Tsunakawa, Takayuki wrote: > I propose changing the default value of wal_sync_method from fdatasync > to open_datasync on Linux. The patch is attached. I'm feeling this > may be controversial, so I'd like to hear your opinions.
Indeed. My past experience with open_datasync on linux shows it to be slower by roughly an order of magnitude. Even if that would turn out not to be the case anymore, I'm *extremely* hesitant to make such a change. > [HDD on VM, ext4 volume mounted with noatime,nobarrier,data=writeback] > (the figures seem oddly high, though; this may be due to some VM > configuration) These numbers clearly aren't reliable, there's absolutely no way an hdd can properly do ~30k syncs/sec. Until there's reliable numbers this seems moot. Greetings, Andres Freund