I have just started the expansion of a RAID 5 from 3x3TB to 4x3TB in a Synology.
This is all very easy, a few clicks and it’s doing its thing for next few days.
But, what actually happens during a RAID 5 expand?
I know the disks are divided into blocks, and a parity block is made. But what are the steps required to expand to a new disk, without losing data or availability?