Обсуждение: Postgres 8.0 Backups
Hi Everybody,
I am working on a backup script for Postgres 8.0 online backups and
since i have to copy the whole pgdata directory , i am wondering after i
copy the pgdata directory can I run gzip or tar on the data directory ?
is it safe to do gzip or tar and I can safely restore the backups later ?
Thanks in advance,
Pallav
On Mon, 2005-01-24 at 10:47, Pallav Kalva wrote: > Hi Everybody, > > I am working on a backup script for Postgres 8.0 online backups and > since i have to copy the whole pgdata directory , i am wondering after i > copy the pgdata directory can I run gzip or tar on the data directory ? > is it safe to do gzip or tar and I can safely restore the backups later ? Yes, however, you may have some issues to deal with. Generally speaking, file system level backups are not the best way to backup postgresql, since they require either shutting down the server or using a snapshot file system to get a coherent backup. File system backups taken by normal copy / tar during database operation may result in backups that don't work when you need them to. pg_dump is generally the better way to back things up, and with the right switches will create a Z compressed tar file automagically for you.
Scott Marlowe <smarlowe@g2switchworks.com> writes:
> On Mon, 2005-01-24 at 10:47, Pallav Kalva wrote:
>> I am working on a backup script for Postgres 8.0 online backups and
>> since i have to copy the whole pgdata directory , i am wondering after i
>> copy the pgdata directory can I run gzip or tar on the data directory ?
> Generally speaking, file system level backups are not the best way to
> backup postgresql, since they require either shutting down the server or
> using a snapshot file system to get a coherent backup.
In the context of online backup operations, that advice isn't relevant
anymore ...
Personally I would do "tar cfz pgdata.tar.gz $PGDATA" or equivalent,
rather than making an explicit copy of the directory tree first.
regards, tom lane
On Mon, 2005-01-24 at 12:05, Tom Lane wrote: > Scott Marlowe <smarlowe@g2switchworks.com> writes: > > On Mon, 2005-01-24 at 10:47, Pallav Kalva wrote: > >> I am working on a backup script for Postgres 8.0 online backups and > >> since i have to copy the whole pgdata directory , i am wondering after i > >> copy the pgdata directory can I run gzip or tar on the data directory ? > > > Generally speaking, file system level backups are not the best way to > > backup postgresql, since they require either shutting down the server or > > using a snapshot file system to get a coherent backup. > > In the context of online backup operations, that advice isn't relevant > anymore ... Really, is this an 8.0 thing then, that I can make file system backups and expect them to be coherent, or did I misunderhear what you meant and this has to do with some other issue I'm not getting?
Scott Marlowe <smarlowe@g2switchworks.com> writes: > On Mon, 2005-01-24 at 12:05, Tom Lane wrote: >> In the context of online backup operations, that advice isn't relevant >> anymore ... > Really, is this an 8.0 thing then, that I can make file system backups > and expect them to be coherent, or did I misunderhear what you meant and > this has to do with some other issue I'm not getting? No, it means that when doing PITR stuff you don't actually care that your base backup isn't consistent --- you expect WAL replay to fix it. See http://www.postgresql.org/docs/8.0/static/backup-online.html regards, tom lane
Tom Lane wrote: > Scott Marlowe <smarlowe@g2switchworks.com> writes: > > On Mon, 2005-01-24 at 12:05, Tom Lane wrote: > >> In the context of online backup operations, that advice isn't relevant > >> anymore ... > > > Really, is this an 8.0 thing then, that I can make file system backups > > and expect them to be coherent, or did I misunderhear what you meant and > > this has to do with some other issue I'm not getting? > > No, it means that when doing PITR stuff you don't actually care that > your base backup isn't consistent --- you expect WAL replay to fix it. > See http://www.postgresql.org/docs/8.0/static/backup-online.html Right, the big issue is that you have to be archiving the WAL logs before you do the filesystem backup, and the WAL files will restore the recovery to a consistent state. -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073