I am currently running a RAID 5 with 4x2 TB disks and would like to grow the array with 2 x 4 TB disks. The goal would be that there is a RAID 5 with 4 x 4 TB (the two 4 TB disks and two RAID 0 with each two 2 TB disks). Unfortunately I don't have enough space to make a full backup, so I can't build a new RAID. The important data is backed up on an offsite server, which leaves about 4TB of unprotected, less important data which I still try to avoid loosing.
What is the safest way to achieve that?
- make a new RAID 1 with the two 4 TB disks copy the data and then add the other disks and change the RAID 1 to RAID 5 and grow it?
- replace two of the 2 TB disks with the new 4 TB disks, merge the freed disks to a RAID 0, add it to replace a third 2 TB disk with the RAID 0, remove the last 2 TB disk and make another RAID 0 and replace the missing 4th disk with it and then grow the Array?
Which of the two options is safest? Is there a better Way of doing what I want?