Re: Alternate Datafile Location

On Thu, Aug 29, 2024 at 7:11 PM Sam Stearns <sam(dot)stearns(at)dat(dot)com> wrote:

> Howdy,
>
> Here's our filesystems:
>
> [postgres(at)xxx data]$ df -h
> Filesystem Size Used Avail Use% Mounted on
> devtmpfs 80G 0 80G 0% /dev
> tmpfs 80G 44M 80G 1% /dev/shm
> tmpfs 80G 716K 80G 1% /run
> tmpfs 80G 0 80G 0% /sys/fs/cgroup
> /dev/mapper/rhel-root 28G 4.5G 23G 17% /
> tmpfs 80G 8.0K 80G 1% /tmp
> /dev/sda2 1014M 457M 558M 46% /boot
> /dev/sda1 599M 5.9M 594M 1% /boot/efi
> /dev/mapper/pgwalvg-pgwalvol 570G 28K 541G 1% /PG_WAL
> /dev/mapper/pgdatavg-pgdatavol 2.3T 28K 2.2T 1% /PGDATA
> tmpfs 16G 0 16G 0% /run/user/1242651222
> tmpfs 16G 0 16G 0% /run/user/1271246868
> [postgres(at)xxx data]$
>
>
"df -Ph -x tmpfs -x devtmpfs" would make that look a lot neater.

> Our Postgres software install and data directory is on root:
>
> [postgres(at)xxx data]$ pwd
> /var/lib/pgsql/16/data
> [postgres(at)thiludbapql01 data]$ df -h .
> Filesystem Size Used Avail Use% Mounted on
> /dev/mapper/rhel-root 28G 4.5G 23G 17% /
> [postgres(at)xxx data]$
>
>
> We want our database datafile storage to be on /PGDATA.
>

Making the $PGDATA environment variable the same as the directory name is
bound to lead to shell errors.

> I don't see anything in the version 16 documentation on how to accomplish
> this.
>

Where did you look?

How was the instance (aka cluster) created?

> I must be missing it somewhere. Could someone please advise?
>

https://www.postgresql.org/docs/16/app-initdb.html

-D *directory*
--pgdata=*directory*
<https://www.postgresql.org/docs/16/app-initdb.html#APP-INITDB-OPTION-PGDATA>

This option specifies the directory where the database cluster should be
stored. This is the only information required by initdb, but you can avoid
writing it by setting the PGDATA environment variable, which can be
convenient since the database server (postgres) can find the data directory
later by the same variable.

--
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