Re: EXT4 ENOSPC Bug

Theodore Tso
2008-12-02T16:47:46Z

On Tue, Dec 02, 2008 at 03:58:53PM +0100, Andres Freund wrote:
> Ok. The system now runs (without problems) with the patch enabled and I can
> get the debug output.
> 30 Minutes after boot the system still returns to zero dirty blocks and the
> free blocks seem to stay in a sensible range.
> I will let it run for a while and report back if either something interesting
> happens or the problem reappears and I am seeing no significant amount of dirty
> blocks.

You say you are using Postgres, right? Something you might try to see
if it triggers the problem it is creating a new database and then
restoring some database dump/backup into that new database. Some
databases expand into a new table space (or whatever terminology
Postgres uses) by random writes into a sparse portion of the file.
This could be triggering the problem, or at least trigger the problem
more quickly.

The other thing I wanted to ask is whether "df" was showing the 37%
in-use statistic at the time, or was that after you rebooted. And
although I hate to ask it, you're sure this isn't the standard "delete
an in-use file but not get the space back" Unix trap, right?

Thanks, regards,

- Ted