In my current Ubuntu server, I have 2x 2TB Western Digital RED hard drives in a RAID 1, using mdadm. I would like to add 2 more 2TB RED drives, and convert it to a RAID 10. I realize I would have to wipe the data most likely, but is there any way that I wouldn't need to? I have the 2TB volume almost completely filled up
If the RAID controller supports restructuring RAID 1 -> RAID 10, yes, possible loss of data.
Software RAID ...
Add the empty net RAID 1 on two new HDD. Will Raid c similar reliability and without the risk of losing data.