Re: symlinking pg_xlog

Last week I was testing PG under different RAID configurations and I moved
pg_xlog to other drives and set up the symlink in the data directory
(pg_xlog -> /home/test/pg-log). PG worked fine and there were no problems

Tim

----------------------
Timothy Shenton
Lycos, Inc.
(781) 370-2876

|---------+-------------------------------->
| | Michael Fuhr |
| | <mike(at)fuhr(dot)org> |
| | Sent by: |
| | pgsql-admin-owner(at)pos|
| | tgresql.org |
| | |
| | |
| | 06/24/2005 09:40 AM |
| | |
|---------+-------------------------------->
>----------------------------------------------------------------------------------------------------------|
| |
| To: KÖPFERL Robert <robert(dot)koepferl(at)sonorys(dot)at> |
| cc: "[ADMIN]" <pgsql-admin(at)postgresql(dot)org> |
| Subject: Re: [ADMIN] symlinking pg_xlog |
>----------------------------------------------------------------------------------------------------------|

On Fri, Jun 24, 2005 at 03:18:12PM +0200, KÖPFERL Robert wrote:
>
> due to I/O-bottle necks I think of making a symlink from pg_xlog to
another
> physical disk.
> This is a modification inside the cluster dir. What kind of idea is that?
> bad one?

See the "Write-Ahead Logging (WAL)" chapter in the documentation:

http://www.postgresql.org/docs/8.0/static/wal-internals.html

"It is of advantage if the log is located on another disk than the
main database files. This may be achieved by moving the directory
pg_xlog to another location (while the server is shut down, of
course) and creating a symbolic link from the original location in
the main data directory to the new location."

Several third-party performance-tuning documents make the same
recommendation.

--
Michael Fuhr
http://www.fuhr.org/~mfuhr/

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