Обсуждение: tar error, in pg_start_backup()

.

On Fri, Apr 16, 2010 at 11:55 AM, raghavendra t
<raagavendra.rao@gmail.com> wrote:
> Hi All,
>
> For some setups reason, i started taking Hot backup. In this course I have first issued pg_start_backup('backup') and
wentto the data directory for backing up in OS format using the command "tar -cf backup.tar  /data" . When i issued
thiscommand , tar was generating some errors as show below. 
>
> bash-3.00# tar -cf 16aprilstandby.tar /db-data/
> tar: Removing leading `/' from member names
> tar: /db-data/base/24643/151667: file changed as we read it
> tar: /db-data/base/24643/151764.2: file changed as we read it
> tar: /db-data/base/24643/151766: file changed as we read it
> tar: /db-data/base/24643/151768: file changed as we read it
> tar: /db-data/base/66412/151969: file changed as we read it
>
> After sometime tar has ended and i also issued pg_stop_backup() and i continued the process.
>
> My question here is, is this errors generated by tar are to worrisome or whats happening in the backend.
> Is "tar" file is safewell to use. Could you please tell me.

Those are not errors, they are warnings. As long as you use
pg_start_backup() and pg_stop_backup() before and after the tar, they
are perfectly harmless, and can be ignored.

--
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/

Magnus Hagander wrote:
> .
>
> On Fri, Apr 16, 2010 at 11:55 AM, raghavendra t
> <raagavendra.rao@gmail.com> wrote:
> > Hi All,
> >
> > For?some setups reason, i started taking Hot backup. In this course I have first issued pg_start_backup('backup')
andwent to the data directory for backing up in OS format using the command "tar -cf backup.tar? /data" . When i issued
thiscommand , tar was generating some errors as show below. 
> >
> > bash-3.00# tar -cf 16aprilstandby.tar /db-data/
> > tar: Removing leading `/' from member names
> > tar: /db-data/base/24643/151667: file changed as we read it
> > tar: /db-data/base/24643/151764.2: file changed as we read it
> > tar: /db-data/base/24643/151766: file changed as we read it
> > tar: /db-data/base/24643/151768: file changed as we read it
> > tar: /db-data/base/66412/151969: file changed as we read it
> >
> > After sometime tar has ended and i also issued pg_stop_backup() and i continued the process.
> >
> > My question here is, is this errors generated by tar are to worrisome or whats happening in the backend.
> > Is "tar" file is safewell to use. Could you please tell me.
>
> Those are not errors, they are warnings. As long as you use
> pg_start_backup() and pg_stop_backup() before and after the tar, they
> are perfectly harmless, and can be ignored.

Yes, and the manual does mention this issue:

    http://developer.postgresql.org/pgdocs/postgres/continuous-archiving.html#BACKUP-BASE-BACKUP

    Some file system backup tools emit warnings or errors if the files they
    are trying to copy change while the copy proceeds. When taking a base
    backup of an active database, this situation is normal and not an error.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com