Re: BUG #5725: server couldn't start when installing on liveCD

On 10/26/2010 02:44 AM, VMaury wrote:

> 2010-10-25 08:45:56 UTC PANIC: could not open file
> "pg_xlog/000000010000000000000000" (log file 0, segment 0): Invalid
> argument

> This bug has been reported by someone else (in spanish):
> https://bugs.launchpad.net/ubuntu/+source/postgresql-8.4/+bug/658857
>
> However, this install works perfectly once Ubuntu is installed.
> Why is there a difference between install and live?
> Thank you very much for your help,

The live CD uses a union file system over the squashfs from the CD. I
seem to remember that the writable part of the union is a tempfs, but
I'm not 100% sure of that. Anyway, the union file system and/or the
underlying tempfs are probably missing features required for
PostgreSQL's operation.

You can probably get it to run by pre-creating the postgresql data
directory and mounting a real file system on it, without the union with
squashfs. A dedicated tempfs might work, so try that. If it doesn't,
you'll need some writable storage (a partition on the computer's hard
disk, an external HDD, even a USB key if you're prepared for
horrifyingly bad performance) to put a real file system like ext3 on.

Even if tempfs works, be aware that it uses your system's RAM - and when
that runs low, spills to swap space. If there isn't enough RAM and
there's no swap space, it'll fail. Of course, the data also goes away on
reboot. It's a very bad place to run PostgreSQL for anything but the
most utterly trivial toy experimentation.

--
Craig Ringer