On Wed, Jan 27, 2010 at 12:38:47AM +0000, Rob Sheldon wrote:
> Hi,
>
> So, the short version is that I have a server with OpenBSD 4.6 that can't
> fsck its big partition; fsck fails with a segfault every time. If I "ulimit
> -d unlimited" before fsck'ing, it just takes a little longer to segfault.
> It produces no other output. IIRC, the partition is roughly 6 TB. Two
> questions then: is there any way through this that doesn't involve
> newfs'ing the partition, and is there a "right" way to do a partition of
> that size in OpenBSD given fsck's 1G hard limit?
No, there is no other way. I've posted a small piece of code some time
ago that estimate the amount of mem needed for doing an fsck during newfs.
Therse days, amd64 is the only platform that increases the limit
(MAXDSIZE) to 8G. Though you venture into untested territory, we
(myself at least) just do not have the hardware to test anything
beyond 2T.
>
> The longer version: this is a backup server running backuppc for a
> corporate client ("large enough number of workstations") that does research
> work ("some really big files"). I _thought_ I had read the big filesystem
> FAQ carefully, but somehow missed that fsck simply couldn't handle anything
> over 1TB without doing funny things during the fs setup. So, this
> particular partition was backuppc's data directory, and it was set up with
> the default block sizes. Also possibly noteworthy: there's no swap, the OS
> and other partitions are all running off of a USB flash drive for various
> reasons.
The SEGVs may be related to not having swap. Running OpenBSD in
overcommitted state is not what you want.
>
> If I have to wipe the partition and start over, it's not a disaster. This
> was a newer server, the old backup server was still online and still had
> some disk left, so I get to keep my butt out of a sling. But, if I'm going
> to have to do that, then I also need to consider whether it might just be
> better to use a different OS. (No foul intended, I'm a big fan of OpenBSD,
> but it just might not be the right tool for this job.)
>
> There's no dmesg attached because I'm not on-site with the server at the
> moment, and because AFAICT this is a known problem.
A pity, since it does matter what platform you run on. fsck needing a
lot of memory is indeed a known problem, but the SEGVs are not. You
might want to check if they still occur when you have enough swap.
-Otto
