| From: | Scott Carey <scott(at)richrelevance(dot)com> |
|---|---|
| To: | Scott Carey <scott(at)richrelevance(dot)com> |
| Cc: | Greg Smith <greg(at)2ndquadrant(dot)com>, "<david(at)lang(dot)hm>" <david(at)lang(dot)hm>, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, Francisco Reyes <lists(at)stringsutils(dot)com>, Pgsql performance <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: 10K vs 15k rpm for analytics |
| Date: | 2010-03-10 00:47:08 |
| Message-ID: | 17E585DB-FF2F-4281-A5D1-7546829AE16C@richrelevance.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
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 a file 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, then write to it. If the whole thing is written to first, then random writes are fine. Postgres only writes random when it overwrites a page, otherwise its always an append operation AFAIK.
> --
> Sent via pgsql-performance mailing list (pgsql-performance(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-performance
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Greg Smith | 2010-03-10 02:32:38 | Re: 10K vs 15k rpm for analytics |
| Previous Message | Scott Carey | 2010-03-10 00:39:25 | Re: 10K vs 15k rpm for analytics |