Thread: PITR - base backup question
From the following link: http://www.postgresql.org/docs/8.3/interactive/continuous-archiving.html#BACKUP-BASE-BACKUP Step 3 says to perform the back up. Does this mean a File System Backup of the Data directory? OR Does this mean performing a pg_dumpall and backing up the dump file? -- Regards, Richard Broersma Jr. Visit the Los Angeles PostgreSQL Users Group (LAPUG) http://pugs.postgresql.org/lapug
Hi Richard,
This means a file systems backup. eg.
tar -cvpf data_bakup.tar /var/lib/pgsql/data
Here's a script I use to automate this process. It may be helpful to
customize for yourself.
#!/bin/bash
#
# PostgreSQL Weekly Backup
#
DATE=$(date +%G%m%d)
MAILLOG="/backup/weekly_$DATE.log"
WALARCH="/pgbackup"
DESTINATION="X.X.X.X::rsyncshare/"
EMAILDEST=""
touch $MAILLOG
echo -e "::::::::::::::: $DATE Pallas1 Weekly WAL Backup :::::::::::::::"
>> $MAILLOG
psql -U postgres -c "select pg_start_backup ('$DATE');"
cd /var/lib/pgsql
tar -cvpzf "pgbackup_$DATE.tar.gz" data/ >> $MAILLOG 2>&1
psql -U postgres -c "select pg_stop_backup ();"
find $WALARCH -perm 600 -mmin "+360" -exec rm {} \; >> $MAILLOG 2>&1
find $WALARCH/data_dir_backup -mtime "+5" -exec rm {} \; >> $MAILLOG 2>&1
ls -la $WALARCH >> $MAILLOG 2>&1
mv /var/lib/pgsql/pgbackup_$DATE.tar.gz /$WALARCH/data_dir_backup/.
rsync -a -v -v --progress --stats --delete "/$WALARCH" $DESTINATION >>
$MAILLOG 2>&1
/bin/cat $MAILLOG | mail -s "Weekly WAL Backup - Successful" $EMAILDEST &&
rm $MAILLOG
On Tue, 26 Aug 2008 15:53:33 -0700, "Richard Broersma"
<richard.broersma@gmail.com> wrote:
> From the following link:
>
http://www.postgresql.org/docs/8.3/interactive/continuous-archiving.html#BACKUP-BASE-BACKUP
>
> Step 3 says to perform the back up.
>
> Does this mean a File System Backup of the Data directory?
> OR
> Does this mean performing a pg_dumpall and backing up the dump file?
>
> --
> Regards,
> Richard Broersma Jr.
>
> Visit the Los Angeles PostgreSQL Users Group (LAPUG)
> http://pugs.postgresql.org/lapug
>
>
On Tue, Aug 26, 2008 at 6:53 PM, Richard Broersma <richard.broersma@gmail.com> wrote: > From the following link: > http://www.postgresql.org/docs/8.3/interactive/continuous-archiving.html#BACKUP-BASE-BACKUP > > Step 3 says to perform the back up. > > Does this mean a File System Backup of the Data directory? > OR > Does this mean performing a pg_dumpall and backing up the dump file? File system backup. You tar up the database folder except pg_xlog (and maybe pg_log). You then expand it on the other side (making sure to set up pg_xlog properly). If you ever want to mess around with log shipping I strongly suggest you go through the motions of setting up a warm standby vi the pg_standby utility and practice popping the standby out of recovery. It will give you a good understanding of the process. merlin
On Tue, Aug 26, 2008 at 5:19 PM, <steve@outtalimits.com.au> wrote: > This means a file systems backup. eg. > > tar -cvpf data_bakup.tar /var/lib/pgsql/data Thanks also for the script. I will take a close look. -- Regards, Richard Broersma Jr. Visit the Los Angeles PostgreSQL Users Group (LAPUG) http://pugs.postgresql.org/lapug
On Tue, Aug 26, 2008 at 5:38 PM, Merlin Moncure <mmoncure@gmail.com> wrote: > If you ever want to mess around with log > shipping I strongly suggest you go through the motions of setting up a > warm standby vi the pg_standby utility and practice popping the > standby out of recovery. Thanks for the reply! I want to be certain that I understand the point you are making: Is setting up a warm standby server good pratice for gaining experience in PITR or do you mean that PITR is a good starting point for setting up a warm standby server? -- Regards, Richard Broersma Jr. Visit the Los Angeles PostgreSQL Users Group (LAPUG) http://pugs.postgresql.org/lapug
On Tue, Aug 26, 2008 at 9:04 PM, Richard Broersma <richard.broersma@gmail.com> wrote: > On Tue, Aug 26, 2008 at 5:38 PM, Merlin Moncure <mmoncure@gmail.com> wrote: > > >> If you ever want to mess around with log >> shipping I strongly suggest you go through the motions of setting up a >> warm standby vi the pg_standby utility and practice popping the >> standby out of recovery. > > Thanks for the reply! I want to be certain that I understand the > point you are making: > > Is setting up a warm standby server good pratice for gaining > experience in PITR or do you mean that PITR is a good starting point > for setting up a warm standby server? setting up a warm standby is good for understanding pitr. A warm standby just 'lays on top' of pitr and you should learn how to do it. merlin
I have what I have sometimes called a 'tepid spare' backup. Once a week I copy the physical files over to another system (actually to two of them) and every few hours I make sure the archived WAL log files are in sync (using rsync.)
Anyway, here's the cookbook guide I wrote for updating one of the backup servers, which I have used several times, so I don't have to rediscover the steps each time. I think it has sufficient detail that someone other than me could follow them. Obviously it would have to be changed to apply to your file organization scheme.
Enjoy!
--
Mike Nolan
How to restore the PostgreSQL low level backup tar files and WAL files
to do a point-in-time recovery (PITR) files on a backup server.
This note will explain how to perform a point-in-time recovery of the
PostgreSQL database using the low-level backup files and the archived
WAL (write-ahead log) files. (These steps should work on either server, with any differences in actual file locations dealt with using symbolic links.)
The low level backup files and WAL log files should already be present
on the backup servers. The low level tar files files are copied when they
are created (usually early on a Tuesday morning each week) and the WAL log
files are rsync'ed to both servers every few hours so that both backup
servers should have files enabling them to be restored to a state that is
no more than a few hours out of sync with the live database server. (In
the future, we hope to keep one of the backup servers in full real-time
synchronization with the live server, using a different technique.)
The steps given below will generally take 3-5 hours to run, depending
on how many archived log files need to be processed when the PostgreSQL
server is restarted.
These instructions assume some familiarity with Unix/Linux system
administration tools, including the vi editor, and with database
administration procedures, though not necessarily detailed knowledge
of PostgreSQL.
For more details, see chapter 23 of the PostgreSQL documentation,
especially section 23.3. The documentation for version 8.2 is at
http://www.postgresql.org/docs/8.2/static/backup.html
1. su to root on the backup server that the restore will be performed on
2. su to postgres (su - postgres)
3. Shut down the Postgresql server running on the backup server, if any
pg_ctl stop
(Use 'ps ax' to make sure the server is stopped.)
4. cd to /disk1/postgres/data and copy two files to /tmp
cd /disk1/postgres/data
cp pg_hba.conf /tmp
cp recovery.done /tmp
5. Delete the entire contents of the /disk1/postgres/data directory tree.
MAKE ABSOLUTELY SURE YOU ARE IN THE /disk1/postgres/data directory!
cd /disk1/postgres/data
pwd
rm -rf *
6. Restore the tar file for the low-level backup from the live server
tar xvf /usr/local/pgsql/tardir/pg_part1.tar
(This restore may take 2-3 hours)
7. Remove the PostgreSQL log file and the WAL files that were restored
from the tar archive
rm log.out
cd pg_xlog
rm 00*
(do not remove the archive_status subdirectory)
8. Copy the pg_hba.conf file back from the /tmp directory
cd /disk1/postgres/data
cp /tmp/pg_hba.conf .
(This is necessary to keep this database server configured for restricted
access. If more expansive access is needed the restored pg_hba.conf
file may be more appropriate.)
9. Copy the recovery configuration file from the /tmp directory (changing
the file name)
cp /tmp/recovery.done recovery.conf
(This file may be edited to do a point-in-time recovery other than
to the end of the PITR log files, see the PostgreSQL documentation for
details.)
10. Delete the entire contents of the /disk2/postgres/data directory tree.
MAKE ABSOLUTELY SURE YOU ARE IN THE /disk2/postgres/data directory!
cd /disk2/postgres/data
pwd
rm -rf *
11. Restore the 2nd tar archive
tar xvf /usr/local/pgsql/tardir/pg_part2.tar
(This restore may take around a half hour)
12. Go to the directory where the WAL files have been archived on
the server and remove all files older than the file matching the
last .backup file. The fastest way to do this is as follows:
cd /usr/local/pgsql/archivedir
ls -1 > files
This will produce a file listing all files in the archivedir directory.
Now edit that file (using vi) to take out all lines after the
latest 'backup' file (including the file just ahead of that backup
file, since it is actually the first file that needs to be processed.
(Note: These ones after the latest backup file are the files we're
NOT going to delete, so we don't want those file names in this text file.)
For example, the directory list may look like this:
00000001000000960000000A
00000001000000960000000B
00000001000000960000000C
00000001000000960000000C.004027C0.backup
00000001000000960000000D
There will generally be several files with the name ending in 'backup',
find the most recent one (ie, the last one in the file.)
In this case, the fie with the name ending in '000C' needs to be
restored, along with all subsequent files, so in this case we would
delete all lines from the one ending in '000C' to the end of the edit
buffer, then edit the lines to change the lines into 'rm' commands,
ie, something like this:
rm 00000001000000960000000A
rm 00000001000000960000000B
Save the edited file, then execute it
sh -x files
13. You are now ready to restart PostgreSQL and have it process all the
archived log files:
pg_ctl -l /usr/local/pgsql/data/log.out start
14. While the WAL files are being processed, a 'ps -ax' display will
have lines in it that look something like this:
28039 pts/0 S 0:00 /disk1/postgres/pgsql/bin/postgres
28040 ? Ds 0:00 postgres: startup process
You can also look at the /usr/local/pgsql/data/log.out file to see
which WAL file it is currently processing:
tail /usr/local/pgsql/data/log.out
Once all the WAL files have been processed (which could take an
hour or longer, depending on how many WAL files need to be processed,
'ps -ax' will look more like this:
28039 pts/0 S 0:00 /disk1/postgres/pgsql/bin/postgres
28310 ? Ss 0:00 postgres: writer process
28311 ? Ss 0:00 postgres: archiver process
28312 ? Ss 0:00 postgres: stats collector process
Once this happens, the backup database server is ready for use.
However, it will only be as current as the most recent WAL file that
was processed, and in order to bring it to a more current state all of
the steps given above have to be performed again.
Anyway, here's the cookbook guide I wrote for updating one of the backup servers, which I have used several times, so I don't have to rediscover the steps each time. I think it has sufficient detail that someone other than me could follow them. Obviously it would have to be changed to apply to your file organization scheme.
Enjoy!
--
Mike Nolan
How to restore the PostgreSQL low level backup tar files and WAL files
to do a point-in-time recovery (PITR) files on a backup server.
This note will explain how to perform a point-in-time recovery of the
PostgreSQL database using the low-level backup files and the archived
WAL (write-ahead log) files. (These steps should work on either server, with any differences in actual file locations dealt with using symbolic links.)
The low level backup files and WAL log files should already be present
on the backup servers. The low level tar files files are copied when they
are created (usually early on a Tuesday morning each week) and the WAL log
files are rsync'ed to both servers every few hours so that both backup
servers should have files enabling them to be restored to a state that is
no more than a few hours out of sync with the live database server. (In
the future, we hope to keep one of the backup servers in full real-time
synchronization with the live server, using a different technique.)
The steps given below will generally take 3-5 hours to run, depending
on how many archived log files need to be processed when the PostgreSQL
server is restarted.
These instructions assume some familiarity with Unix/Linux system
administration tools, including the vi editor, and with database
administration procedures, though not necessarily detailed knowledge
of PostgreSQL.
For more details, see chapter 23 of the PostgreSQL documentation,
especially section 23.3. The documentation for version 8.2 is at
http://www.postgresql.org/docs/8.2/static/backup.html
1. su to root on the backup server that the restore will be performed on
2. su to postgres (su - postgres)
3. Shut down the Postgresql server running on the backup server, if any
pg_ctl stop
(Use 'ps ax' to make sure the server is stopped.)
4. cd to /disk1/postgres/data and copy two files to /tmp
cd /disk1/postgres/data
cp pg_hba.conf /tmp
cp recovery.done /tmp
5. Delete the entire contents of the /disk1/postgres/data directory tree.
MAKE ABSOLUTELY SURE YOU ARE IN THE /disk1/postgres/data directory!
cd /disk1/postgres/data
pwd
rm -rf *
6. Restore the tar file for the low-level backup from the live server
tar xvf /usr/local/pgsql/tardir/pg_part1.tar
(This restore may take 2-3 hours)
7. Remove the PostgreSQL log file and the WAL files that were restored
from the tar archive
rm log.out
cd pg_xlog
rm 00*
(do not remove the archive_status subdirectory)
8. Copy the pg_hba.conf file back from the /tmp directory
cd /disk1/postgres/data
cp /tmp/pg_hba.conf .
(This is necessary to keep this database server configured for restricted
access. If more expansive access is needed the restored pg_hba.conf
file may be more appropriate.)
9. Copy the recovery configuration file from the /tmp directory (changing
the file name)
cp /tmp/recovery.done recovery.conf
(This file may be edited to do a point-in-time recovery other than
to the end of the PITR log files, see the PostgreSQL documentation for
details.)
10. Delete the entire contents of the /disk2/postgres/data directory tree.
MAKE ABSOLUTELY SURE YOU ARE IN THE /disk2/postgres/data directory!
cd /disk2/postgres/data
pwd
rm -rf *
11. Restore the 2nd tar archive
tar xvf /usr/local/pgsql/tardir/pg_part2.tar
(This restore may take around a half hour)
12. Go to the directory where the WAL files have been archived on
the server and remove all files older than the file matching the
last .backup file. The fastest way to do this is as follows:
cd /usr/local/pgsql/archivedir
ls -1 > files
This will produce a file listing all files in the archivedir directory.
Now edit that file (using vi) to take out all lines after the
latest 'backup' file (including the file just ahead of that backup
file, since it is actually the first file that needs to be processed.
(Note: These ones after the latest backup file are the files we're
NOT going to delete, so we don't want those file names in this text file.)
For example, the directory list may look like this:
00000001000000960000000A
00000001000000960000000B
00000001000000960000000C
00000001000000960000000C.004027C0.backup
00000001000000960000000D
There will generally be several files with the name ending in 'backup',
find the most recent one (ie, the last one in the file.)
In this case, the fie with the name ending in '000C' needs to be
restored, along with all subsequent files, so in this case we would
delete all lines from the one ending in '000C' to the end of the edit
buffer, then edit the lines to change the lines into 'rm' commands,
ie, something like this:
rm 00000001000000960000000A
rm 00000001000000960000000B
Save the edited file, then execute it
sh -x files
13. You are now ready to restart PostgreSQL and have it process all the
archived log files:
pg_ctl -l /usr/local/pgsql/data/log.out start
14. While the WAL files are being processed, a 'ps -ax' display will
have lines in it that look something like this:
28039 pts/0 S 0:00 /disk1/postgres/pgsql/bin/postgres
28040 ? Ds 0:00 postgres: startup process
You can also look at the /usr/local/pgsql/data/log.out file to see
which WAL file it is currently processing:
tail /usr/local/pgsql/data/log.out
Once all the WAL files have been processed (which could take an
hour or longer, depending on how many WAL files need to be processed,
'ps -ax' will look more like this:
28039 pts/0 S 0:00 /disk1/postgres/pgsql/bin/postgres
28310 ? Ss 0:00 postgres: writer process
28311 ? Ss 0:00 postgres: archiver process
28312 ? Ss 0:00 postgres: stats collector process
Once this happens, the backup database server is ready for use.
However, it will only be as current as the most recent WAL file that
was processed, and in order to bring it to a more current state all of
the steps given above have to be performed again.
On Wed, Aug 27, 2008 at 9:18 AM, Michael Nolan <htfoot@gmail.com> wrote: > I have what I have sometimes called a 'tepid spare' backup. Once a week I > copy the physical files over to another system (actually to two of them) and > every few hours I make sure the archived WAL log files are in sync (using > rsync.) I have a couple of comments...see below: > 3. Shut down the Postgresql server running on the backup server, if any > pg_ctl stop > (Use 'ps ax' to make sure the server is stopped.) probably pg_ctl -m fast stop or -m immediate...since we are overwriting it. > 5. Delete the entire contents of the /disk1/postgres/data directory tree. > MAKE ABSOLUTELY SURE YOU ARE IN THE /disk1/postgres/data directory! > > cd /disk1/postgres/data > pwd > rm -rf * why not just rm -rf /disk1/postgres/data? > 6. Restore the tar file for the low-level backup from the live server > > tar xvf /usr/local/pgsql/tardir/pg_part1.tar > > (This restore may take 2-3 hours) > > 7. Remove the PostgreSQL log file and the WAL files that were restored > from the tar archive I prefer to exclude WAL files from the original tar, and recreate the folders here (being careful to chown them to postgres account). Every little bit helps. > 12. Go to the directory where the WAL files have been archived on > the server and remove all files older than the file matching the > last .backup file. The fastest way to do this is as follows: > > cd /usr/local/pgsql/archivedir > ls -1 > files This is a nice touch. With a little bash-fu you could do a find | xargs rm and list/kill the files in one pass. In the standby setups I've done I usually script the whole process, a prep on the main and a startup on the standby. merlin
On Wed, Aug 27, 2008 at 8:32 AM, Merlin Moncure <mmoncure@gmail.com> wrote:
Good point, but sometimes there are tasks running on the backup server (recently I did a test of a revised procedure that took 5 days to run.) I'll probably update the cookbook guide to deal with that possibility.
I prefer the visual confirmation that I am indeed in the right directory rather than risk a typo in the longer rm command.
Another good point.
The scripts to create the system level backups and copy them to the backup servers and to rsync the WAL files are both cron jobs.
I've considered writing a script to do all the restore tasks on the backup server, but I figure if someone other than me ever has to do it, for example if there is a problem when I'm unavailable, that person will probably want to watch the entire process carefully, since he or she will be far less familiar with the configuration.
As disk space permits, I actually keep TWO sets of the tar archive base files, the most recent one and the one from the previous week. That way I could go back further for a PITR recovery up to some incident. I've never needed to do that and I hope I never do, but it's nice to have that capability just in case.
--
Mike Nolan
> 3. Shut down the Postgresql server running on the backup server, if any> pg_ctl stopprobably pg_ctl -m fast stop or -m immediate...since we are overwriting it.
> (Use 'ps ax' to make sure the server is stopped.)
Good point, but sometimes there are tasks running on the backup server (recently I did a test of a revised procedure that took 5 days to run.) I'll probably update the cookbook guide to deal with that possibility.
why not just rm -rf /disk1/postgres/data?
> 5. Delete the entire contents of the /disk1/postgres/data directory tree.
> MAKE ABSOLUTELY SURE YOU ARE IN THE /disk1/postgres/data directory!
>
> cd /disk1/postgres/data
> pwd
> rm -rf *
I prefer the visual confirmation that I am indeed in the right directory rather than risk a typo in the longer rm command.
> 6. Restore the tar file for the low-level backup from the live server>I prefer to exclude WAL files from the original tar, and recreate the
> tar xvf /usr/local/pgsql/tardir/pg_part1.tar
>
> (This restore may take 2-3 hours)
>
> 7. Remove the PostgreSQL log file and the WAL files that were restored
> from the tar archive
folders here (being careful to chown them to postgres account). Every
little bit helps.
Another good point.
> 12. Go to the directory where the WAL files have been archived onThis is a nice touch. With a little bash-fu you could do a find |
> the server and remove all files older than the file matching the
> last .backup file. The fastest way to do this is as follows:
>
> cd /usr/local/pgsql/archivedir
> ls -1 > files
xargs rm and list/kill the files in one pass. In the standby setups
I've done I usually script the whole process, a prep on the main and a
startup on the standby.
The scripts to create the system level backups and copy them to the backup servers and to rsync the WAL files are both cron jobs.
I've considered writing a script to do all the restore tasks on the backup server, but I figure if someone other than me ever has to do it, for example if there is a problem when I'm unavailable, that person will probably want to watch the entire process carefully, since he or she will be far less familiar with the configuration.
As disk space permits, I actually keep TWO sets of the tar archive base files, the most recent one and the one from the previous week. That way I could go back further for a PITR recovery up to some incident. I've never needed to do that and I hope I never do, but it's nice to have that capability just in case.
--
Mike Nolan
--- On Tue, 8/26/08, Richard Broersma <richard.broersma@gmail.com> wrote: > From: Richard Broersma <richard.broersma@gmail.com> > Subject: [GENERAL] PITR - base backup question > To: "pgsql-general@postgresql.org" <pgsql-general@postgresql.org>, pgsql-admin@postgresql.org > Date: Tuesday, August 26, 2008, 10:53 PM > From the following link: > http://www.postgresql.org/docs/8.3/interactive/continuous-archiving.html#BACKUP-BASE-BACKUP > > Step 3 says to perform the back up. > > Does this mean a File System Backup of the Data > directory? > OR > Does this mean performing a pg_dumpall and backing up > the dump file? > is a file system backup of he data directory > -- > Regards, > Richard Broersma Jr.
On Wed, Aug 27, 2008 at 9:52 AM, Michael Nolan <htfoot@gmail.com> wrote: >> This is a nice touch. With a little bash-fu you could do a find | >> xargs rm and list/kill the files in one pass. In the standby setups >> I've done I usually script the whole process, a prep on the main and a >> startup on the standby. > > The scripts to create the system level backups and copy them to the backup > servers and to rsync the WAL files are both cron jobs. > > I've considered writing a script to do all the restore tasks on the backup > server, but I figure if someone other than me ever has to do it, for example > if there is a problem when I'm unavailable, that person will probably want > to watch the entire process carefully, since he or she will be far less > familiar with the configuration. Here are some basic facts of life about PITR/log shipping. It is a disaster prevention feature. Here's the scenario: You are going to depend upon it on 3 a.m. early saturday morning three years in the future, only you are not going to be there. A drive just went out on the main, but instead of degrading the entire backplane went amber. You are going to be in Barbados on your honeymoon, with no connectivity to the outside world (your blushing bride made you leave the laptop at home). The guy doing the switchover to the standby is the only one that could be gotten a hold of, he still hasn't gotten over the 12 hour bender from Friday. He's never really understood why your company took your advice and went with PostgreSQL instead of SQL Server, is cranky, and doesn't like you that much. He secretly hopes the standby wont come up and barely knows how to use a console. write the script. test it. merlin
---------------------------------------- > Date: Wed, 27 Aug 2008 06:58:33 -0700 > From: lennin.caro@yahoo.com > Subject: Re: [ADMIN] [GENERAL] PITR - base backup question > To: pgsql-general@postgresql.org; pgsql-admin@postgresql.org; richard.broersma@gmail.com > > > > > --- On Tue, 8/26/08, Richard Broersma wrote: > >> From: Richard Broersma >> Subject: [GENERAL] PITR - base backup question >> To: "pgsql-general@postgresql.org" , pgsql-admin@postgresql.org >> Date: Tuesday, August 26, 2008, 10:53 PM >> From the following link: >> http://www.postgresql.org/docs/8.3/interactive/continuous-archiving.html#BACKUP-BASE-BACKUP >> >> Step 3 says to perform the back up. >> >> Does this mean a File System Backup of the Data >> directory?\ It is a file system backup, we use PITR and every time we need a new checkpoint we create a TAR file of the postgresql homedirectory >> OR >> Does this mean performing a pg_dumpall and backing up >> the dump file? >> > is a file system backup of he data directory >> -- >> Regards, >> Richard Broersma Jr. > > > > > > > -- > Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-admin