Re: Moving pg_xlog
От | Brad Nicholson |
---|---|
Тема | Re: Moving pg_xlog |
Дата | |
Msg-id | 429E1B2A.1000605@ca.afilias.info обсуждение исходный текст |
Ответ на | Re: Moving pg_xlog ("Keith Worthington" <keithw@narrowpathinc.com>) |
Список | pgsql-performance |
Keith Worthington wrote: >On Wed, 01 Jun 2005 12:19:40 -0400, Tom Lane wrote > > >>"Keith Worthington" <keithw@narrowpathinc.com> writes: >> >> >>>I have been reading about increasing PostgreSQL performance >>>by relocating the pg_xlog to a disk other than the one >>>where the database resides. I have the following pg_xlogs >>>on my system. >>> >>>/raid02/databases/pg_xlog >>>/raid02/rhdb_databases/pg_xlog >>>/raid02/databases-8.0.0/pg_xlog >>>/var/lib/pgsql/data/pg_xlog >>> >>>I have no idea why the forth entry is there. It is in the PostgreSQL >>>installation directory. >>> >>> >>It's there because the RPM sets up a database under /var/lib/pgsql/data. >> >> >> >>>1) stop the postmaster >>>2) rm -rf /var/lib/pgsql/data/pg_xlog >>>3) mv /raid02/databases/pg_xlog /var/lib/pgsql/data/pg_xlog >>>4) ln -s /var/lib/pgsql/data/pg_xlog /raid02/databases/pg_xlog >>>5) start postmaster >>> >>> >>Put the xlog anywhere BUT there!!!!!!!!! >> >> >> >>>If I can do that and place the pg_xlog in the installation >>>directory will I create any installation issues the next >>>time I upgrade PostgreSQL? >>> >>> >>Oh, the installation will be just fine ... but your database will not >>be after the upgrade wipes out your WAL. Put the xlog under some >>non-system-defined directory. >> >> regards, tom lane >> >>---------------------------(end of broadcast)--------------------------- >>TIP 7: don't forget to increase your free space map settings >> >> > >Thanks Tom. I am glad I asked before I leaped. 8-0 > >Is there a convention that most people follow. It would seem that anywhere in >the installation directory is a bad idea. From what I have read on other >threads it does not want to be in the database directory since in most cases >that would put it on the same disk as the database. > > > We tend to use somthing that associates the WAL with the appropriate cluster, like /var/lib/CLUSTER for the data /var/lib/CLUSTER_WAL for WAL files. >I am assuming due to lack of reaction that the symbolic link is not an issue. > Is there a cleaner or more appropriate way of moving the pg_xlog. > > > A symbolic link is the standard way to do it. >Finally, am I correct in assuming that as long as the postmaster is shut down >moving the log is safe? > > You are correct. Moving the WAL files with the postmaster running would be a very bad thing. -- Brad Nicholson 416-673-4106 Database Administrator, Afilias Canada Corp.
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