Hi,
that is generally not a problem. _fsm is the "Free Space Map" file
(http://www.postgresql.org/docs/9.4/static/storage-fsm.html). It's OK
and normal, that files change or even disappear within PGDATA directory
during backup - because the Postgres cluster is still operational. Those
changes end up in the WAL files and that is why you need those from the
start of the backup. This is also described in the manual:
"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. However, you need to ensure that you can distinguish complaints
of this sort from real errors. For example, some versions of rsync
return a separate exit code for "vanished source files", and you can
write a driver script to accept this exit code as a non-error case.
Also, some versions of GNU tar return an error code indistinguishable
from a fatal error if a file was truncated while tar was copying it.
Fortunately, GNU tar versions 1.16 and later exit with 1 if a file was
changed during the backup, and 2 for other errors. With GNU tar version
1.23 and later, you can use the warning options
--warning=no-file-changed --warning=no-file-removed to hide the related
warning messages."
http://www.postgresql.org/docs/9.4/interactive/continuous-archiving.html#BACKUP-LOWLEVEL-BASE-BACKUP
hth
Jan
Am 2015-05-21 09:04, schrieb Mario Aguado:
> Hi,
>
> I have two postgres cluster in 9.4 version and all run backups
> correctly. Recently I add a new cluster and the backup doesnt work on
> it.
>
> All databases have archive_mode = on and wal_level=archive
>
> My backup has this steeps:
>
> SELECT pg_start_backup(${clustername});"
> tar PGDATA and TABLESPACES
> Select pg_stop_backup();
> tar WAL files
>
> With this database when I run backup I get errors like:
>
> t3_28961_fsm: File removed before we read it
>
> I dont know what file type is t3_28961_fsm.
>
> If I go to tablespace dir i have several t files and this file types
> are adding and removing continously.
>
> -rw------- 1 postgres postgres 8.0K May 21 09:01 t3_29094
> -rw------- 1 postgres postgres 0 May 21 09:01 t3_29087
> -rw------- 1 postgres postgres 8.0K May 21 09:01 t3_29093
>
> Im looking for this error but i didnt found any.
>
> Any idea?
>
> Thanks in advance.
>
> Regards.
>
> Mario