Re: Backing up large databases

Just to say thanks to all for your constructive and helpful replies - I
will build a new server with 8.1 and slony.

Steve

Steve Burrows wrote:
> I am struggling to find an acceptable way of backing up a PostgreSQL
> 7.4 database.
>
> The database is quite large, currently it occupies about 180GB,
> divided into two elements, a set of active tables and a set of archive
> tables which are only used for insertions.
>
> I ran pg_dump -Fc recently, it took 23.5 hours to run, and output a
> single file of 126GB. Obviously as the database continues to grow it
> will soon be so large that it cannot be pg_dumped within a day.
> Running rsync to do a complete fresh copy of the pgsql file structure
> took 4 hours, but later that day running another iteration of rsync
> (which should have only copied changed files) took 3 hours, and I
> cannot afford to have the db down that long.
>
> Anybody with any ideas? The database is being used as the backend for
> a mail server, so it has transactions 24 hours a day but is quieter at
> night. I want to be able to back it up or replicate it on a daily
> basis with minimum downtime so that the mail backlog doesn't get too
> large. Ideally I want the first generation of backup/replica going
> onto the same machine as the original because the volume of data is
> such that any attempt at network or tape backup of the live files will
> require too much downtime, once I've got a backup then I can copy that
> out to other NAS or tape at leisure.
>
> If anyone has experience of safeguarding a similarly large PostgreSQL
> database with minimal downtime I'd be delighted to hear.. The machine
> is running 2 Xeons, 4GB ram and a half-terabyte RAID10 array on a DELL
> PERC scsi subsystem, with a load average of around 0.5 - 0.6, so it's
> not exactly overstretched.
>
> Thanks,
>
> Steve