Re: binary logs: a location other than pg_xlog??

"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> James Cloos <cloos(at)jhcloos(dot)com> wrote:
>> I notice that everyone suggests using a symlink, but I never see
>> anyone suggest just mounting a filesystem there.

> I think initdb wants an empty directory. Once it creates the
> directory structure with pg_xlog, if that's a mount point, it's a
> bit awkward to mount there and then copy from behind the mount point
> onto it. A symbolic link seems both safer and easier.

Well, either way you're going to have to modify things after initdb.

The notion of mounting a filesystem directly there scares me, on the
whole. Here is the problem: what if someday that filesystem happens not
to be mounted? Then you have a bare mountpoint directory, with no real
way for the postmaster to notice that that wasn't what you intended.
Hilarity ensues. (You might want to go back a few years in the archives
and read Joe Conway's report of what happened to his DB when a soft NFS
mount was a bit slow to mount one day. The symptoms for a missing
pg_xlog directory would be different but not better.) A symlink seems
to have a bit more error detection capability built in, especially if
you don't symlink to exactly the filesystem mount point but rather a
directory level or two down, so that the target dir is not there if the
mount fails.

regards, tom lane