On Mar 9, 2010, at 4:39 PM, Scott Carey wrote:
>
> On Mar 8, 2010, at 11:00 PM, Greg Smith wrote:
>
> * At least with CentOS 5.3 and thier xfs version (non-Redhat, CentOS extras) sparse random writes could almost hang
afile system. They were VERY slow. I have not tested since.
>
Just to be clear, I mean random writes to a _sparse file_.
You can cause this condition with the 'fio' tool, which will by default allocate a file for write as a sparse file,
thenwrite to it. If the whole thing is written to first, then random writes are fine. Postgres only writes random
whenit overwrites a page, otherwise its always an append operation AFAIK.
> --
> Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-performance
