Re: Postgresql Software Location

> On Aug 29, 2024, at 2:12 PM, Henry Ashu <henry(dot)ashu(at)dat(dot)com> wrote:
>
> We have installed our postgresql software in this location:
>
> [postgres(at)testdbapql01 data]$ pwd
> /var/lib/pgsql/16/data
> [postgres(at)testbapql01 data]$ df -h .
> Filesystem Size Used Avail Use% Mounted on
> /dev/mapper/rhel-root 28G 4.5G 23G 17% /
> [postgres(at)testdbapql01 data]$
>
> Does this look correct? We are thinking that it should not be installed on the root filesystem.
> Thank you
>
> Henry Ashu
>
> Database Administrator
> o: 503.672.5114 | f: 800.551.8821 | DAT.com
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Yes, it is better to have more mount points than not. Root should be its own mount point; OSs do not like when the root volume is full thus it is normally a very small filesystem.

Disclaimer: I’ve seen servers with a single mount point /. A lot of devops servers are setup with a single mount point for the entire OS. Seems like that is the case with your system. The reason to have multiple filesystem is space management, mount point options, and filesystem corruption. I haven’t had the need to run fsck in decades until last month. An xfs volume was corrupted and even fsck couldn’t fix it; had to resort to a filesystem snapshot.

I normally have three;

1. /var/log — for log files via syslog. You don’t want a run away application to full up the log directory and crash the server.
2. $PGDATA — data volume
3. $PGDATA/pg_wal — Normally, I’m using ZFS with different filesystem properties. It’s also a good idea to manage the space separately.

As far as absolute mount points that’s a preference; my current gig is using the following with the instance names as a directory under those mount points.

/pg_data
/pg_wal