Snapshots that won't delete [was: Re: ZFS on root booting...]

[Adam Vande More]

On Fri, Sep 12, 2014 at 12:12 AM, Shane Ambler <FreeBSD at shaneware.biz>
wrote:

> On 11/09/2014 16:42, Ben Morrow wrote:
> > Quoth Adam McDougall <mcdouga9 at egr.msu.edu>:
> >>
> >> Were you running a newer kernel with an older format zpool?  I heard
> >> ixsystems had customers doing that and ran into corruption when they
> >> tried to modify the zpool in some way (expand? I don't remember).
> >> http://www.bsdnow.tv/episodes/2014_07_09-zfs_war_stories
> >
> > Oh! Might this be what's causing a problem I've been meaning to ask
> > about?
> >
> > My desktop at home is running (a patched, but not anywhere to do with
> > ZFS) 10-STABLE from a while ago, with a zpool that was created under
> > 8.2-R and is still at version 15. I have been deliberately not upgrading
> > it, because I saw no reason to and it seemed safer to leave things as
> > they were.
> >
> > Recently, though, my dump script has started having occasional problems
> > with snapshots that won't delete. Pending further investigation I have
> > been renaming them to allow the recursive delete to succeed, and (so
> > far) rebooting has always made it possible to get rid of them.
>
> I have seen that issue with 9.2 and at least one other person mentioned
> it as well. I currently have a snapshot that I accessed at least 3 weeks
> ago and renamed to keep rotations working and have not accessed since,
> it still won't delete as it is busy. I can only delete these snapshots
> after a reboot.
>
> The only cause I know is accessing the snapshot.
> I can simply ls .zfs/snapshot/daily.01/somefolder to prevent it being
> deleted. With a manual zfs destroy I get "dataset is busy" and have not
> found a way to find any process that has hold of it.


What exactly have you tried and what were the results?


-- 
Adam