zfs discuss - Apr 2009 - tmpfs under zfs pool

On Wed, Apr 01, 2009 at 01:41:06AM +0300, Dimitar Vasilev
wrote:
> Hi all,
> Could someone give a hint if it''s possible to create rpool/tmp,
mount
> it as /tmp so that tmpfs has some disk-based back-end instead of
> memory-based size-limited one.
You mean you want /tmp to be a regular ZFS filesystem instead of a
tmpfs one.  Yes, that''s possible.

There is no dedicated disk back end for tmpfs, only swap (which may
include disk-based backing store).
> When I do regular creation of rpool/tmp without setting any mountpoint
> options and entry in vfstab i''m dropped into single user, because
> fs-local service cannot mount the rpool/tmp fs.
> What I could do is set the mount point to legacy and describe it in
> vfstab for mounting so that tmpfs entry does not get blocked.
You mean so the /tmp entry doesn''t get blocked (it won''t be a
tmpfs
entry if you do this).

Do you need a /tmp entry at all for this?  If you just set the
mountpoint to be /tmp (leave it out of vfstab entirely), then I think
it''ll work, but it won''t be available until all the ZFS
filesystems
mount.

I''ll have to try that and see if anything breaks.

-- 
Darren

On Wed, Apr 01, 2009 at 12:41:25AM +0000, A Darren Dunham
wrote:
> On Wed, Apr 01, 2009 at 01:41:06AM +0300, Dimitar Vasilev wrote:
> > Hi all,
> > Could someone give a hint if it''s possible to create
rpool/tmp, mount
> > it as /tmp so that tmpfs has some disk-based back-end instead of
> > memory-based size-limited one.
> 
> You mean you want /tmp to be a regular ZFS filesystem instead of a
> tmpfs one.  Yes, that''s possible.
> I''ll have to try that and see if anything breaks.
Aside from being a bit slower to complete login, it seemed to work
okay.  (Worked much better after I set correct permissions on the
rpool/tmp directory).

-- 
Darren