[lxc-devel] [PATCH 1/1] lxc-create: add zfs support

[Serge Hallyn]

Quoting Serge Hallyn (serge.hallyn at ubuntu.com):
> <ping> Any feedback on this patch?
> 
> I also have a question on behavior details.  Until now, we've set up
> btrfs containers so that $lxcpath is a subvolume, and then each
> $rootfs is a subvolume.  With zfs, per Papp's request, we're making
> the (zfs equivalent of a subvolume) at the $lxcpath/$lxc_name.  So
> that means when we make a snapshot clone, we'll be doing them
> differently for different filesystems.
> 
> I don't really care which we do - and even if we keep them different
> for hysterical raisins it's not biggie technically, since the
> filesystems have to be handled differently at clone anyway.  But
> it'll be harder to explain to users what's going on.
> 
> With the btrfs way, when we snapshot-clone a container we have to
> manually copy all the config and hooks files.  We have to process
> them anyway (s/oldname/newname etc) though.  With the zfs way we
> wouldn't have to copy them - so files which we didn't predict won't
> be copied.  That may be a good thing - if we didn't predict it, then
> we probably didn't process it anyway so it may not be safe.  Still
> the zfs way feels elegant...

To reply to myself,

as we also support snapshot-clones of lvm, and soon qcow and qed
based containers, and those will only snapshot the rootfs, if we
want behavior with all backing stores to be consistent then zfs
would need to change to only snapshot the rootfs, not $lxcpath/$lxc_name.

-serge