What's the trick to Samba shadow_copy2 and Windows' "Previous Versions" support?

[Jim L.]

I have a working Samba share that I'm trying to implement Shadow Copy support on:

[test]
   path = /data/test
   browsable = yes
   writable = yes
   create mask = 0770
   directory mask = 0770
   vfs objects = zfsacl shadow_copy2
   nfs4: mode = special
   nfs4: chown = true
   nfs4: acedup = merge
   map system = no
   map archive = no
   map readonly = no
   store dos attributes = yes
   ;inherit owner = yes
   inherit owner = windows and unix
   hide unreadable = yes
   admin users = tom mary hans jim
   valid users = tom mary hans jim
   comment = Test dataset with Previous Versions enabled
   shadow:snapdir = .zfs/snapshot
   shadow:sort = desc
   shadow:format = %Y%m%d%H%M%S-SAN

Here's what my snapshots look like, so I hope my shadow:format directive is correct:

# zfs list -rt snap tank/mountable/test
NAME                                         USED  AVAIL  REFER  MOUNTPOINT
tank/mountable/test@20250402122744-SAN   146K      -   238K  -
tank/mountable/test@20250402122805-SAN   146K      -   256K  -

The filesystem is mounted directly at the root of the share:

# df -h /data/test
Filesystem                 Size    Used   Avail Capacity  Mounted on
tank/mountable/test     57T    293K     57T     0%    /data/test

And yet, even after restarting the Samba service, Windows Explorer reports "no previous versions available."

What am I missing?

 

[CeXP1917]

In some manuals I saw

shadow:format = GMT-%Y.%m.%d_%H.%M.%S

as correct naming format.

 

[Jim L.]

I was under the impression that Samba just needed the format string to be able to strptime(3) the snapshot name from a string to a sortable datestamp, and thus, the shadow:format string just had to match the format one uses for one's snapshot names.

Nevertheless, changing:

# for fullsnap in $(zfs list -Ht snap -o name tank/mountable/test); do snap=${fullsnap#*@}; echo zfs rename $fullsnap GMT-${snap:0:4}.${snap:4:2}.${snap:6:2}_${snap:8:2}.${snap:10:2}.${snap
:12:2}; done | sh -v
zfs rename tank/mountable/test@20250402122744-SAN GMT-2025.04.02_12.27.44
zfs rename tank/mountable/test@20250402122805-SAN GMT-2025.04.02_12.28.05

# zfs list -t snap tank/mountable/test
NAME                                          USED  AVAIL  REFER  MOUNTPOINT
tank/mountable/test@GMT-2025.04.02_12.27.44   146K      -   238K  -
tank/mountable/test@GMT-2025.04.02_12.28.05   146K      -   256K  -

and

shadow:format = GMT-%Y.%m.%d_%H.%M.%S

and restarting Samba makes no change; still no previous versions found.

Do you have a working example?

 

[CeXP1917]

Do you have a working example?

No, I wanted to do same thing with shadow copies, but found that for my purposes "zfs set snapdir=visible" on shared fs is enough.
May be you need shadow:basedir = /data/test