Replicating pool root to pool root

TrueNAS General
1

Hi *,
using the GUI for creating a replication task, I can choose a pool root as source (for example pool_archiv) and another pool root (for example pool_backup) as target. After the task has finished, pool_backup contains 1:1 the same structure as pool_archiv.
Trying that using the commandline (after having created a snapshot), I always get an error:

/sbin/zfs send -v pool_archiv@snapshot-archiv-Tuesday | /sbin/zfs receive -v pool_backup

cannot receive new filesystem stream: destination 'pool_backup' exists
must specify -F to overwrite it

What am I missing here? What does the GUI do differently? And how does the GUI handle first vs. subsequent runs of the same replication?

TIA.

Bye.
Michael.

2

This is what I use for cloning my desktop, (which uses ZFS);

zfs send  -Rpv  ${MY_SRC_POOL}@${MY_SNAP} | \
  zfs receive -dFu ${MY_DEST_POOL}

Note that using “-v” on both the send and receive processes could make the output confusing. Try one or the other.

3

Thx for your answer.
Using -F on the receive side doesn’t give this error message, but wouldn’t it replicate everything again then in a second run? Or do I have to omit -F in subsequent runs?

Btw.:

 -p, --props
           Include the dataset's properties in the stream.  This flag is implicit when -R is specified.

So shouldn’t “-R” be enough?

4

I don’t do incremental runs for that OS copy process. It’s only 20GB to 45GBs and reasonably fast, even to a MicroSD card. So I re-create the pool each copy, (no more than once a month). This also has the side benefit of reducing fragmentation.

As for “-R” being enough. Perhaps. Whence I scripted it and proved it worked, I did not bother examining it further.

5

I have to replicate about 4 TB of data, so recreating the target pool every days isn’t an option, I think. I didn’t find any advice, yet, if first and subsequent replications can be done with the same options, and if not, what options are necessary for them. Do you have some link for me? Probably I look for the wrong words.

As for the script, of course you are right.

6

Sorry, no I do not have any information other than reading the manual pages. I had to fumble through them because ZFS Replication is quite a bit different from the old UFS Dump & Restore.