Re: Defaulting wal_sync_method to fdatasync on Linux for 9.1?

On Wed, Nov 17, 2010 at 3:24 PM, Greg Smith <greg@2ndquadrant.com> wrote:
> Scott Carey wrote:
>>
>> Did you recompile your test on the RHEL6 system?
>
> On both systems I showed, I checked out a fresh copy of the PostgreSQL 9.1
> HEAD from the git repo, and compiled that on the server, to make sure I was
> pulling in the appropriate kernel headers.  I wasn't aware of exactly how
> the kernel sync stuff was refactored though, thanks for the concise update
> on that.  I can do similar tests on a RHEL5 system, but not on the same
> hardware.  Can only make my laptop boot so many operating systems at a time
> usefully.

One thing to note is that where on a disk things sit can make a /huge/
difference - depending on if Ubuntu is /here/ and RHEL is /there/ and
so on can make a factor of 2 or more difference.  The outside tracks
of most modern SATA disks can do around 120MB/s. The inside tracks
aren't even half of that.

--
Jon