On 2010-10-22 17:37, Greg Smith wrote: > I think that most people who have thought they were safe to turn off > full_page_writes in the past did so because they believed they were > in category (1) here. I've never advised anyone to do that, because > it's so difficult to validate the truth of. Just given that, I'd be > tempted to join in on suggesting this parameter just go away in the > name of safety, except that I think category (2) here is growing now. > ZFS is the most obvious example where the atomic write implementation > seems to always make disabling full_page_writes safe.
Can you point to some ZFS docs that tell that this is the case.. I'd be surprised if it doesnt copy away the old block and replaces it with the new one in-place. The other behaviour would quite quickly lead to a hugely fragmented filesystem that performs next to useless and ZFS doesnt seem to be in that category..