Re:

> I am interested in the file system level backup:
>
> http://www.postgresql.org/idocs/index.php?backup-file.html
>
> Is there any documentation/ suggestions on restoring file system
> backups.

It would be identical to Oracle's cold backup strategy (about which I'm
sure you'll find volumes on the web).

It is actually rather simple in concept:

1. tar up your entire Postgres directory (assuming your databases live
within the Postgres directory) after you've shut down all your
databases.

2. Wait until database crashes and is irrecoverable.

3. De-tar your Postgres backup into the directory again.

4. Start up your database.

5. Be delighted about how well it worked out, but because you're paranoid,
do as many queries as you can on the data to see if it looks sane.

Of course, it is suggested you replace step #2 with: "Every now and then
when you're paranoid do steps 3-5 somewhere."

I suggest you read any backup and recovery book. I particularly recommend
Unix Backup and Recovery here: http://www.backupcentral.com/thebook.html
-- that book, although dealing not with database backups, will cover 90%
of the concepts you need to understand Postgres "cold" filesystem-level
backups.

As a DBA, though, I'd finally give you this advice: use the online backup
facility. It shouldn't be any more difficult, and it will let you leave
the database up and running whilst you backup.

--
Tim Ellis
DBA, Gamet