zfs discuss - Apr 2007 - Move data from the zpool (root) to a zfs file system

Hi List,

As a ZFS newbie, I foolishly copied my data set to the root zpool file 
system (a large iSCSI SAN array). Thus:

# zpool create -f iscsi c4t19d0 c4t20d0 c4t21d0 c4t22d0 c4t23d0 c4t24d0
# zpool list
NAME                    SIZE    USED   AVAIL    CAP  HEALTH     ALTROOT
iscsi                  9.53T   64.5K   5.34T    0%  ONLINE     -
# zfs set mountpoint=/mydisks/iscsi iscsi

Then copied almost 6TB (uncompressed) of data into a subdirectory of the 
root zpool: /mydisks/iscsi/fastdata.  (I know, RTFM before using ZFS). 
So, now for many obvious reasons I want to move my data into a 
filesystem below my iscsi zpool (call: iscsi/fastdata).  So I tried the 
following:

# cd /mydisks/iscsi
# ls 
fastdata/
# mv fastdata fastdata.old/
# zfs snapshot iscsi at today
# zfs clone iscsi at today iscsi/fastdata
# zfs list
NAME                   USED  AVAIL  REFER  MOUNTPOINT
iscsi                 4.04T  5.34T  4.04T  /mydisks/iscsi
iscsi at today               0      -  4.04T  -
iscsi/fastdata            0  5.34T  4.04T  /mydisks/iscsi/fastdata
# zfs promote iscsi/fastdata
# zfs list
NAME                   USED  AVAIL  REFER  MOUNTPOINT
iscsi                 4.04T  5.34T  4.04T  /mydisks/iscsi
iscsi/fastdata        4.04T  5.34T  4.04T  /mydisks/iscsi/fastdata
iscsi/fastdata at today      0      -  4.04T  -

Clean up the original subdirectory:

# pwd
/mydisks/iscsi
# rm -r fastdata.old/
.. some time later...
# zfs list
NAME                   USED  AVAIL  REFER  MOUNTPOINT
iscsi                 4.04T  5.34T  27.5K  /mydisks/iscsi
iscsi/fastdata        4.04T  5.34T  4.04T  /mydisks/iscsi/fastdata
iscsi/fastdata at today      0      -  4.04T  -

And in new file system:

# pwd
/mydisks/iscsi/fastdata
# mv fastdata.old/* .
# rmdir fastdata.old

OK, so far so good.  But now I want to remove the snapshot, and this is where
I''m stuck:

# zfs destroy iscsi/fastdata at today
cannot destroy ''iscsi/fastdata at today'': dataset already
exists
# zfs destroy -r iscsi/fastdata at today
cannot destroy ''iscsi/fastdata at today'': snapshot is cloned
no snapshots destroyed
# zfs list -o origin iscsi
ORIGIN
iscsi/fastdata at today

As you can see, the origin of the snapshot is the iscsi zpool root file system. 
D''oh!  Furthermore, if I promote the iscsi root FS, the iscsi/fastdata
subdirectory becomes a clone:

# zfs promote iscsi
# zfs list -o origin iscsi
ORIGIN
-
# zfs list -o origin iscsi/fastdata
ORIGIN
iscsi at today

So, I can promote the iscsi zpool FS, but then the new iscsi/fastdata FS becomes
a clone of the snapshot.  I can''t have both iscsi and iscsi/fastdata
promoted so I can clean out the snapshot.  Am I stuck just copying the data into
the new file system, which will take, by my calculations 12 days, or is there
another secret approach I can take here?  Yes, I''m an idiot for not
creating the file system in the first place, but you learn from your mistakes,
right?  Any  help/suggestions would be very much appreciated.

Thanks,

Jon



-- 


-     _____/     _____/      /           - Jonathan Loran -           -
-    /          /           /                IT Manager               -
-  _____  /   _____  /     /     Space Sciences Laboratory, UC Berkeley
-        /          /     /      (510) 643-5146 jloran at ssl.berkeley.edu
- ______/    ______/    ______/           AST:7731^29u18e3

Jonathan Loran wrote:
> So, I can promote the iscsi zpool FS, but then the new iscsi/fastdata FS 
> becomes a clone of the snapshot.  I can''t have both iscsi and 
> iscsi/fastdata promoted so I can clean out the snapshot.  Am I stuck 
> just copying the data into the new file system, which will take, by my 
> calculations 12 days, or is there another secret approach I can take 
> here?  Yes, I''m an idiot for not creating the file system in the
first
> place, but you learn from your mistakes, right?  Any  help/suggestions 
> would be very much appreciated.
Unfortunately, there is no way to destroy or rename the topmost 
filesystem (the one with the same name as the pool), so you are stuck 
copying the data over.  I believe there are some RFEs filed about this 
issue, if not, feel free to file them.

--matt