So, long story short, I have spent the last week or so moving data off array disks, reformating some old drives from Reiserfs to XFS and moving the data back. Because I had 16 array drives and a buttload of data to move around, I disabled my 2 parity drives and used them in unassigned devices to store data while doing this.
While in this process, I have noticed that one of my array drives is VERY slow (maybe 10-15MB/s) while every other drive gets copied to at about 183MB/s (with parity disabled).
Usually, if I wanted to swap a drive out I would replace it and let parity rebuild it, however with them currently disabled I wanted to know if I can install a new drive, use new config to swap it in the array, and mount the old drive using unassigned devices to copy the data back. I have tried, and the drive is slowing parity rebuild times so I thought this might be a more efficient way to go about this.
Obviously I have all VMs and dockers disabled while doing this to ensure nothing else is writing to the array.
So, is this something I can do?