Re: initial sync of multiple streaming slaves simultaneously

Our sync script is setup to fail if the pg_start_backup fails as if it
fails for some other reason the sync won't be valid as the backup_label
file will be missing so the slave won't have the correct location to
restart from.

Originally I had gone down the road of changing the sync script such that
if the pg_start_backup failed and the backup_label file existed it would
sync the backup_label right away so it could then do the sync. It was also
setup so that if it didn't start the backup it wouldn't stop the backup.
This however didn't work as if the DR starts the backup and begins it sync
first, and the local slave then goes to startup and the backup is already
in progress it would complete the sync faster then the DR and then try to
start up. But the local slave would not come up into hot standby until the
stop_backup was executed (it came up but would never switch over to allow
readonly queries).

At that point I was going to change the script to basically be whoever got
to the point of needing to stop the backup first would call stop backup.
But the new procedure of calling start and then stop right away seems
simpler (it makes the slave startup script simpler for sure).

On Wed, Sep 19, 2012 at 10:05 AM, Mike Roest <mike(dot)roest(at)replicon(dot)com>wrote:

>
> Specifically what is the error?
>>
> psql (9.1.5)
> Type "help" for help.
>
> postgres=# select pg_start_backup('hotbackup',true);
> pg_start_backup
> -----------------
> 61/B000020
> (1 row)
>
> postgres=# select pg_start_backup('hotbackup',true);
> ERROR: a backup is already in progress
> HINT: Run pg_stop_backup() and try again.
> postgres=#
>
>