Re: symlinking pg_xlog - Mailing list pgsql-admin

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@fuhr.org>      |
|         |           Sent by:             |
|         |           pgsql-admin-owner@pos|
|         |           tgresql.org          |
|         |                                |
|         |                                |
|         |           06/24/2005 09:40 AM  |
|         |                                |
|---------+-------------------------------->
  >----------------------------------------------------------------------------------------------------------|
  |                                                                                                          |
  |        To:      KÖPFERL Robert <robert.koepferl@sonorys.at>                                              |
  |        cc:      "[ADMIN]" <pgsql-admin@postgresql.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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