So, the parity check completed, then the server locked up and you replaced the drive? I'm confused.
If something got lost in translation, I was asking when the last error free parity check happened prior to the drive change.
You can't assign a smaller drive to a slot. Once you removed the old drive and replaced it with a larger one it expanded the partition to fill the larger drive. The parity emulated bits that were on the old drive were written to the new drive. The reason I'm asking about the last parity check is if parity was NOT valid when the drive was removed, what was written to the new drive is corrupted.
What you can do is operate on the old drive using the Unassigned Devices plugin, see if it mounts, and if not, run the file system check there.