Re: initdb when data/ folder has mount points

Ron Johnson <ron.l.johnson@cox.net> writes:

Apparently, initdb assumes that data/ is one big mount point. However, we 
have four mount points:
/var/lib/pgsql/9.6/data/backup
/var/lib/pgsql/9.6/data/base
/var/lib/pgsql/9.6/data/pg_log
/var/lib/pgsql/9.6/data/pg_xlog

Don't do that.

There's no reason for backup storage to be under the data directory (and
lots of good reasons for it not to be).  Just put it somewhere else.

The supported way to put pg_xlog on a separate volume is to put that
mount point somewhere else, and make $PGDATA/pg_xlog be a symlink to
it.  IIRC, there's an initdb option to help with that, though you can
also make it so manually after initdb.

For pg_log, just put it somewhere else and set the appropriate
configuration option to say where to write the postmaster log files.
Or you could use a symlink, like the solution for pg_xlog, but
I don't see any advantage there.

I don't see any point in making base/ be its own mount point.  Once
you get rid of those other subdirectories there's not going to be
enough "global" storage left to justify its own volume.

I'm replicating the structure in our existing systems.  Is there an (up to date) Best Practices document for these kinds of issues?