LocalSnapshotsOnly
Sometimes a user might want to have only a NAS server with snapshots, and no backup server (not adviseable, but it is a possible choice anyway).
This scenario was suggested to me by my friend Francesco. Thank you, Frank! :)
In detail, his use case is just having a nas that can perform local snapshots, which could be browsed via Samba as we already have set up.
So let's modify some files and perform a local snapshot without performing a backup.
In order to perform just a snapshot, we need to use the switch -s and the complete backup descriptor. Clearly, in this case, since no remote backup server will be contacted, the part of the descriptor that describes the remote server can be fake. Here is an example:
SRC_POOL=zfspool
SRC_DATASET=Documents
DST_POOL=fakepool
DST_DATASET=FakeDir
DST_USERNAME=fuser
DST_ADDR=fake
Let's create a file like this and name it ExampleDocumentsLocalSnapshots.bkp.
If you launch a snapshot operation with no changes in the Documents folder, the script recognizes that and does not create any useless snapshot:
user@nas:~/src/zfs-backup$ ./zfs-backup.sh -s ExampleDocumentsLocalSnapshots
####################################################################################################
ZFS Backup Script - server name = nas
####################################################################################################
Starting Zfs backup - Snapshot operaton requested.
Snapshot requested on zfspool/Documents
Latest Snapshot is zfspool/Documents@2024.10.27-21.59.11
Finding differences between zfspool/Documents@2024.10.27-21.59.11 and current status of zfspool/Documents - this could take some time...
There are no local differences -> the latest local snapshot will be considered as current snapshot.
Snapshot operaton complete
user@nas:~/src/zfs-backup$ zfs list -t snapshot
NAME USED AVAIL REFER MOUNTPOINT
zfspool/Documents@2024.07.26-00.48.47 346K - 474M -
zfspool/Documents@2024.10.27-21.59.11 0B - 474M -
user@nas:~/src/zfs-backup$
As you can see, the last snapshot was zfspool/Documents@2024.10.27-21.59.11, which is the same listed by the command zfs list -t snapshot.
Now we will perform 3 more snapshots:
user@nas:~/src/zfs-backup$ ./zfs-backup.sh -s ExampleDocumentsLocalSnapshots
####################################################################################################
ZFS Backup Script - server name = nas
####################################################################################################
Starting Zfs backup - Snapshot operaton requested.
Snapshot requested on zfspool/Documents
Latest Snapshot is zfspool/Documents@2024.10.27-21.59.11
Finding differences between zfspool/Documents@2024.10.27-21.59.11 and current status of zfspool/Documents - this could take some time...
There are differences -> creating a snapshot...
Creating snapshot...
Snapshot performed correctly: zfspool/Documents@2024.10.27-22.13.33
Snapshot operation complete.
Here is the corresponding content:
user@nas:~/src/zfs-backup$ ./zfs-backup.sh -s ExampleDocumentsLocalSnapshots
####################################################################################################
ZFS Backup Script - server name = nas
####################################################################################################
Starting Zfs backup - Snapshot operaton requested.
Snapshot requested on zfspool/Documents
Latest Snapshot is zfspool/Documents@2024.10.27-22.13.33
Finding differences between zfspool/Documents@2024.10.27-22.13.33 and current status of zfspool/Documents - this could take some time...
There are differences -> creating a snapshot...
Creating snapshot...
Snapshot performed correctly: zfspool/Documents@2024.10.27-22.15.19
Snapshot operation complete.
Here is the corresponding content:
user@nas:~/src/zfs-backup$ ./zfs-backup.sh -s ExampleDocumentsLocalSnapshots
####################################################################################################
ZFS Backup Script - server name = nas
####################################################################################################
Starting Zfs backup - Snapshot operaton requested.
Snapshot requested on zfspool/Documents
Latest Snapshot is zfspool/Documents@2024.10.27-22.15.19
Finding differences between zfspool/Documents@2024.10.27-22.15.19 and current status of zfspool/Documents - this could take some time...
There are differences -> creating a snapshot...
Creating snapshot...
Snapshot performed correctly: zfspool/Documents@2024.10.27-22.18.59
Snapshot operation complete.
Here is the corresponding content:
Here is the final situation of our nas, with several snapshots.
Let's say that, after some local snapshot, we made up our mind and now we want to backup all the situation we have on nas over to the backup server. Let's check out Backup after several snapshots !