On 2015-03-22 12:54:37 -0700, Josh Berkus wrote:
> On 03/22/2015 06:45 AM, Andres Freund wrote:
> > FWIW, I think that's a myth. One I heard various versions of by now. As
> > long as the OSs page size (4kb nearly everywhere) is different from
> > postgres' (8kb) you can have torn pages. Even if individual filesystem
> > page writes are atomic.
>
> ZFS's block size is larger than Linux's memory page size. That is, ZFS
> on Linux uses a 8kB to 128kB block size depending on which blocks you're
> looking at and how you have it configured. Does that make a difference
> at all, given that Linux's memory page size is still 4kB?
No, it does not make a differencen. The page cache is still 4kb.
> FYI, the BTRFS folks are also claiming to be torn-page-proof, so it
> would be really nice to settle this. Not sure how to force the issue
> through testing though.
I don't think this applies here.
Greetings,
Andres Freund
-- Andres Freund http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services