[Samba] frequent tdb corruption

[Adam Thorn]

Hi Andrew,

> Can you please clarify:
> 
>  - Is the filesystem on this disk in any way shared?
>  - Is the block device involved in any way shared?

I'm not 100% sure what you mean by "shared" in this context, but the
filesystem where the tdbs are stored is: pair of local disks => mirrored
together via zfs => zfs filesystem.

In case it's relevant: the samba config files are stored on a different
filesystem. There are a set of multiple disks which are mirrored over
the network with FreeBSD's HAST (pretty much equivalent to DRBD), and
the HAST devices are then combined into a RAIDZ2 pool. I have recently
had some disk problems with the filesystem where the samba config files
are stored (but no problems with the filesystem which stores the tdbs) -
is there any mechanism whereby e.g. a timeout in smbd trying to read
it's config file could cause problems with the tdbs?

>  - Has the server ever had a unexpected poweroff?

No; I installed a different version of FreeBSD (downgraded from 9.1 to
9.0) a week ago to see if it made any difference. The OS partitions were
totally wiped and reinstalled, and since then the server has been
powered-up and stable, and still exhibiting corrupt tdbs.

>  - Do Samba processes ever crash?

No.

> If the answer is no to all these, then I would strongly suspect a
> hardware or OS/kernel issue.  

I'd have said the same, but I've seen this problem on two (nominally)
identical pieces of hardware (whilst that doesn't rule out hardware, I
think it reduces the likelihood). I do plan to run memtest etc when I
can, though.  Also, I'm running the same OS/kernel on another server
which is *almost* identical hardware, and that's been completely
trouble-free for over a year.

> Could you put your TDB files on a different file system, to rule in our
> out ZFS (or the glue between FreeBSD and ZFS)?

I can certainly give that a go!

Thanks for the help,

Adam