Re: Linked directory or explicit reference

[Ron Johnson <ronljohnsonjr@xxxxxxxxx>]

On Tue, Apr 30, 2024 at 7:00 PM Senor Cervesa <frio_cervesa@xxxxxxxxxxx> wrote:

Hi All;

When doing an initial install of PostgreSQL on RHEL 7 or 8 derived OS via rpm, what are pros, cons and recommendations of these 2 procedures for utilizing a second disk?

Secondary SSD or RAID mounted at /disk2.

Option #1

1. install the rpm which creates basic user and home
2. Create symlink /var/lib/pgsql/15/data --> /disk2/data
3. initdb with no special options

Or Option #2

1. install the rpm which creates basic user and home
2. initdb with --pgdata=/disk2/data
   Probably using included 'postgresql-12-setup' script

I also link /var/lib/pgsql/data  --> ../15/data so automation can reference postgresql.conf without knowing version (legacy stuff).

In my experience,The PgBackRest restore feature does not like symlinks.

 

The install is automated with a bash script which handles several options including whether there is a second disk for DB. Scripting the install with or without the second disk is straight forward but I'm concerned with either scenario causing unforeseen differences.

I don't think there's a benefit to using tablespace here but I have no experience with it. The systemd service is configured with a dependency on the disk mount so I don't think there are different risks for starting postgres with missing data directory.

I've run postgres in both scenarios and not had any issues. I'm interested in comments from others on their experience using these or other options.

Is the mount point just "/disk2" when using "--pgdata=/disk2/data"?  I've gotten "directory not empty" errors when the mount point is "/Database/x.y/data".