Don't forget to keep your
mdadm.conf uptodate when creating, modifiying, deleting mdadm arrays.
Grow RAID 5 to RAID 6¶
DON'T FORGET TO SPECIFY THE
mdadm --grow operations!
Otherwise if the host is (forced) shutdowned (e.g., power failure), data can / will be lost.
(This "backup file" should be on different disk / storage, not on the mdadm array you are growing!)
Speed-up RAID rebuild¶
This may or may not improve your mdadm RAID rebuild performance, as it the speed depends on many factors such as disk speeds, etc.
This assumes your disks are
sdc, and the RAID array is
1 2 3 4 5 6 7 8 9 10 11 12 13