Keep the following key points in mind when you receive a file system snapshot:
Both the snapshot and the file system are received.
The file system and all descendent file systems are unmounted.
The file systems are inaccessible while they are being received.
The original file system to be received must not exist while it is being transferred.
If the file system name already exists, you can use zfs rename command to rename the file system.
For example:
# zfs send tank/gozer@0830 > /bkups/gozer.083006 # zfs receive tank/gozer2@today < /bkups/gozer.083006 # zfs rename tank/gozer tank/gozer.old # zfs rename tank/gozer2 tank/gozer
If you make a change to the destination file system and you want to perform another incremental send of a snapshot, you must first roll back the receiving file system.
Consider the following example. First, make a change to the file system as follows:
sys2# rm newtank/dana/file.1
Then, perform an incremental send of tank/dana@snap3. However, you must first roll back the receiving file system to receive the new incremental snapshot. Or, you can eliminate the rollback step by using the –F option. For example:
sys1# zfs send -i tank/dana@snap2 tank/dana@snap3 | ssh sys2 zfs recv -F newtank/dana
When you receive an incremental snapshot, the destination file system must already exist.
If you make changes to the file system and you do not roll back the receiving file system to receive the new incremental snapshot or you do not use the –F option, you see a message similar to the following:
sys1# zfs send -i tank/dana@snap4 tank/dana@snap5 | ssh sys2 zfs recv newtank/dana cannot receive: destination has been modified since most recent snapshot
The following checks are performed before the –F option is successful:
If the most recent snapshot doesn't match the incremental source, neither the roll back nor the receive is completed, and an error message is returned.
If you accidentally provide the name of different file system that doesn't match the incremental source specified in the zfs receive command, neither the rollback nor the receive is completed, and the following error message is returned:
cannot send 'pool/fs@name': not an earlier snapshot from the same fs