Re: Obsolete ToDo Item?

On Wed, Jul 16, 2014 at 02:39:03PM -0700, Jeff Janes wrote:
> On Wed, Jul 16, 2014 at 1:21 PM, Thomas Kellerer <spam_eater(at)gmx(dot)net> wrote:
>
> Hi,
>
> I was reading trough the ToDo list in the Postgres Wiki and noticed that
> one item for Fsync[1] seems to be obsolete:
>
>    Determine optimal fdatasync/fsync, O_SYNC/O_DSYNC options and whether
> fsync does anything
>        Ideally this requires a separate test program like /contrib/
> pg_test_fsync that can be run at initdb time or optionally later.
>
> This was added with 9.1[2] , so I guess that item can be removed from the
> Wiki page?
>
>
> The to-do item is not for pg_test_fsync to be created, but rather for initdb to
> automatically invoke pg_test_fsync and then analyze the results and use that
> analysis to set up the fsync method.
>
> But I do think this entry is obsolete.  If a certain method is "too fast", is
> that because the operating system lies and is not really syncing the data, or
> is it because you have a BBU/NVRAM in front of the disk?  Or because you aren't
> using spinning disk at all?  I don't think that there is any way for initdb to
> safely figure out what is going on just based on the outcome of some timing
> tests.  The person who purchased the hardware has to apply their knowledge.

TODO item removed.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ Everyone has their own god. +