What was the reason for offlining the drive?Well, it was my first disk replacement and I forgot how I tested all 5 drives before creating the pool a few years ago.
So I put the "da4" drive OFFLINE (out of 5 drives)
Put the new drive in the same bay (I forgot I had to test it)
Ran short rest
Ran long test
Is running badblocl test
Now I realize I have a degraded zpool for as long as the 5th drive is not ready.
What should I do?
Should I just stop the tests, run the "replace" command, resilver and hope fort the best ?
If you haven't performed the replacement yet, maybe you could reinsert the old drive and resilver the pool. It may take less time as entire resilvering may not be necessary.
In that case, I would proceed with Badblock and wait for it to complete. Then if all is good, you can replace the old drive with the new drive.