zfs discuss - Jul 2007 - snv_70 -> snv_66: ZPL_VERSION 2, File system version mismatch ....?

Yesterday I was surprised because an old snv_66 kernel
(installed as a new zfs rootfs) refused to mount.
Error message was

    Mismatched versions:  File system is version 2 on-disk format,
    which is incompatible with this software version 1!


I tried to prepare that snv_66 rootfs when running snv_70 bits,
using something like this

   zfs create tank/s11-root-xen
   zfs set mountpoint=legacy tank/s11-root-xen
   mount -F zfs tank/s11-root-xen /mnt
   cd /mnt
   ufsdump 0f - /dev/rdsk/c4d0s4 | ufsrestore -xf -
   ...


Problem is that snv_70 "zfs create" now seems to construct
ZPL_VERSION 2 zfs filesystems, which cannot be mounted
by older version of the zfs software, e.g. by snv_66 or s10u2.

Btw. I never upgraded this zpool to a zpool version > 2, 
to allow using that zpool and zfs filesystems both with
Nevada and S10.

Now it seems I still could work around that problem with
ZPL_VERSION mismatch by booting the oldest Solaris
release that is supposed to mount a zfs filesystem and
create the zfs filesystem from there.


How about a new feature for "zpool create" and "zfs create"
to
allow creation of a zpool or zfs that is not using the newest
version but some older version (that the user has specified on
the command line), so that the new zpool or zfs can be used on
older systems (e.g. on hotpluggable / removable media, or on a
disk that is shared between different Solaris releases)?
 
 
This message posted from opensolaris.org

hi J??rgen,

On Fri, 2007-07-20 at 05:04 -0700, J??rgen Keil wrote:
> How about a new feature for "zpool create" and "zfs
create" to
> allow creation of a zpool or zfs that is not using the newest
> version but some older version
Yep, that''s there already - PSARC 2007/328 gives "zfs
upgrade" and you
can set the version at create time:

# zfs create -o version=1 tank/foo

PSARC 2007/342 will give zpool the same ability during create time, but
it''s not done yet.

(Eric posted about this a few days ago on zfs-discuss. More at:
http://www.opensolaris.org/os/community/arc/caselog/2007/342/
http://www.opensolaris.org/os/community/arc/caselog/2007/328/ )

	cheers,
			tim