Skip site navigation (1) Skip section navigation (2)

Re: WAL archiving

From: Shilpa Sudhakar <ssudhakar(at)internode(dot)com(dot)au>
To: Vishal Arora <aroravishal22(at)hotmail(dot)com>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: WAL archiving
Date: 2008-02-25 06:23:39
Message-ID: 47C25EEB.7080602@internode.com.au (view raw or flat)
Thread:
Lists: pgsql-admin
Thanks Vishal. I got it now.
Will test the archiving process.



Vishal Arora wrote:
>
>
>
>
>
> ------------------------------------------------------------------------
>
> > Date: Mon, 25 Feb 2008 15:30:46 +1030
> > From: ssudhakar(at)internode(dot)com(dot)au
> > To: aroravishal22(at)hotmail(dot)com
> > CC: pgsql-admin(at)postgresql(dot)org
> > Subject: Re: [ADMIN] WAL archiving
> >
> > Thanks a lot Vishal for the info.
> >
> > I have one more query postgres automatically cleans the WAL files
> > present in the pg_xlog directory....right?
>
> YES! it actually recycles the files which are of no further intrest.
>  
> So instead of me creating a separate folder as i've done in my current
> > settings (wal_log), should i need to change the archive_command to 
> point
> > to pg_xlog directly.
>
> NO! In this case it would try to overwrite the existing WAL files. 
> pg_xlog already contains the WAL files .. whats the point archiving 
> the files at the same place.
>  
> Refer to Chapter 23.3.1 (8.2) of the Manual -
>
> "The archive command should generally be designed to refuse to 
> overwrite any pre-existing archive file. This is an important safety 
> feature to preserve the integrity of your archive in case of 
> administrator error (such as sending the output of two different 
> servers to the same archive directory). It is advisable to test your 
> proposed archive command to ensure that it indeed does not overwrite 
> an existing file, and that it returns nonzero status in this case. "
>
>
> > In this way i can avoid a separate process of deleting old files.
> >
> > Please let me know if my understanding is right.
> >
> > Thanks and Regards,
> > Shilpa
> >
> >
> >
> > Vishal Arora wrote:
> > >
> > >
> > >
> > >
> > >
> > > 
> ------------------------------------------------------------------------
> > >
> > > > Date: Mon, 25 Feb 2008 09:53:35 +1030
> > > > From: ssudhakar(at)internode(dot)com(dot)au
> > > > To: aroravishal22(at)hotmail(dot)com
> > > > Subject: Re: [ADMIN] WAL archiving
> > > >
> > > > Hi Vishal,
> > > >
> > > > Below is the setup in the postgresql.conf file
> > > >
> > > > fsync = true # turns forced synchronization on or off
> > > > wal_sync_method = fsync # the default varies across platforms:
> > > > #wal_buffers = 8 # min 4, 8KB each
> > > > #commit_delay = 0 # range 0-100000, in microseconds
> > > > #commit_siblings = 5 # range 1-1000
> > > >
> > > > # - Checkpoints -
> > > >
> > > > checkpoint_segments = 3 # in logfile segments, min 1, 16MB each
> > > > checkpoint_timeout = 300 # range 30-3600, in seconds
> > > > checkpoint_warning = 30 # 0 is off, in seconds
> > > >
> > > > # - Archiving -
> > > >
> > > > archive_command = 'cp -i %p /usr/local/var/pgsql/data/wal_log/%f'
> > > > # command to use to archive a logfile segment
> > > >
> > > > Since this is the test system i've put the wal_log folder in the 
> data
> > > > folder itself. But, later on i'll be moving this to a different 
> disk.
> > > >
> > > > We have thousands and thousands of records that get inserted and
> > > updated
> > > > so the wal logs would be increasing in a large rate. I was thinking
> > > if i
> > > > want to delete the wal logs after a period of time, do i take a base
> > > > backup again and then delete those old files?
> > >
> > > Not required actually. Once you have base backup and Archived WAL in
> > > place, you need not take a base backup again. In case of a crash you
> > > just have to restore from the base backup and the server would start
> > > in restore mode. In restore.conf file you have to specify the
> > > restore_command - which would point towards the archived WAL files.
> > > Yes Once the WAL has been archived you can delete the old WAL files,
> > > which is also done by the postgres itself. It replaces the old(not
> > > required) WAL files with the new one.
> > >
> > > > Thanks and Regards,
> > > > Shilpa
> > > >
> > > >
> > > > Vishal Arora wrote:
> > > > >
> > > > > Hi Shilpa,
> > > > >
> > > > > You need not take base backup again and again. You have WAL
> > > Archiveing
> > > > > in place, that is enough to restore the database. BTW, what 
> archiving
> > > > > command are you using for WAL Archiving in you postgresql.conf.
> > > > >
> > > > > - Vishal
> > > > >
> > > > >
> > > 
> ------------------------------------------------------------------------
> > > > >
> > > > > > Date: Fri, 22 Feb 2008 09:53:25 +1030
> > > > > > From: ssudhakar(at)internode(dot)com(dot)au
> > > > > > To: pgsql-admin(at)postgresql(dot)org
> > > > > > Subject: [ADMIN] WAL archiving
> > > > > >
> > > > > > Hi All,
> > > > > >
> > > > > > I am new to postgres and have been slowly learning the concepts.
> > > > > >
> > > > > > Regarding WAL archiving, we first take a base backup and then
> > > save all
> > > > > > the wal logs for PITR.
> > > > > >
> > > > > > Both the base backup and wal logs are stored in another disk.
> > > > > >
> > > > > > Since the wal logs keep increasing, do we take the base backup
> > > every
> > > > > now
> > > > > > and then so that we can delete the old log files?
> > > > > > How often do we take a base filesystem backup keeping in mind
> > > that our
> > > > > > systems are 24 x 7.
> > > > > >
> > > > > > Any suggestions are appreciated.
> > > > > >
> > > > > > Thanks and Regards,
> > > > > > Shilpa
> > > > > >
> > > > > >
> > > > > > ---------------------------(end of
> > > broadcast)---------------------------
> > > > > > TIP 9: In versions below 8.0, the planner will ignore your 
> desire to
> > > > > > choose an index scan if your joining column's datatypes do not
> > > > > > match
> > > > >
> > > > >
> > > > >
> > > 
> ------------------------------------------------------------------------
> > > > > It's about getting married. Click here! Try it!
> > > > > <http://ss1.richmedia.in/recurl.asp?pid=201>
> > > >
> > >
> > >
> > > 
> ------------------------------------------------------------------------
> > > Post free auto ads on Yello Classifieds now! Try it now!
> > > <http://ss1.richmedia.in/recurl.asp?pid=255>
> >
> >
> > ---------------------------(end of broadcast)---------------------------
> > TIP 6: explain analyze is your friend
>
>
> ------------------------------------------------------------------------
> Detailed profiles 4 marriage! Only at Shaadi.com Try it! 
> <http://ss1.richmedia.in/recurl.asp?pid=107>


In response to

pgsql-admin by date

Next:From: Praveen Kumar (TUV)Date: 2008-02-25 06:38:03
Subject: Re: WAL archiving
Previous:From: Scott MarloweDate: 2008-02-25 06:08:02
Subject: Re: Backup to Tape Incomplete

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group