Hi Stephen,

Please elaborate more of what you are saying. What i am saying is based on
the Official Docs, Forum and our own test. This is what we had to do to
save time, both backing up and  restoring.

https://www.postgresql.org/docs/9.6/static/functions-admin.html

When PostgreSQL in the mode of Start Backup, PostgreSQL only writes to the
XLOG, then you can safely rsync / copy the base data (snapshot) then later
you can have full copy of snapshot backup data.
if you wanted to backup in later day, you can use rsync then it will copy
faster because rsync only copy the difference, rather than copy all the
data.

my latter explanation is: use pg_basebackup, it will do it automatically
for you.

CMIIW,




Julyanto SUTANDANG

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On Sun, Jan 22, 2017 at 9:55 PM, Stephen Frost <sfr...@snowman.net> wrote:

> Greetings,
>
> * julyanto SUTANDANG (julya...@equnix.co.id) wrote:
> > Best practice in doing full backup is using RSYNC, but before you can
> copy
> > the DATADIR, you might you pg_start_backup to tell the server not to
> write
> > into the DATADIR, because you are copying that data. After finished copy
> > all the data in DATADIR, you can ask server to continue flushing the data
> > from logs, by commanding pg_stop_backup. Remember, not to copy the XLOG
> > dir.
>
> Whoah.  That is not, at all, correct, if I'm understanding what you're
> suggesting.
>
> PG most certainly *does* continue to write into the data directory even
> after pg_start_backup() has been run.  You *must* use archive_command or
> pg_receivexlog to capture all of the WAL during the backup to have a
> consistent backup.
>
> > There are another way more simpler, which is applying command
> > pg_basebackup, which actually did that way in simpler version.
>
> pg_basebackup has options to stream the WAL during the backup to capture
> it, which is how it handles that.
>
> > if you did pg_dump, you wont get the exact copy of your data, and you
> will
> > take longer downtime to recover the backup data. By that way, recovering
> is
> > only starting up the postgres with that copy.
>
> pg_dump will generally take longer to do a restore, yes.  Recovering
> from a backup does require that a recovery.conf exists with a
> restore_command that PG can use to get the WAL files it needs, or that
> all of the WAL from the backup is in pg_xlog/pg_wal.
>
> Please do not claim that PG stops writing to the DATADIR or BASEDIR
> after a pg_start_backup(), that is not correct and could lead to invalid
> backups.
>
> Thanks!
>
> Stephen
>

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