Migrate from RAID5 + hot spare to RAID6 after degraded

[jds580s]

I was hoping I could get some advice on the least painful path to my goal of swapping a bad drive and upgrading my array on my QNAP TS-459 Pro.
The unit originally had four 1.5TB drives in a RAID5 + hot spare configuration. One drive failed a few months back and I swapped it for a 3TB NAS rated drive with the idea being that I would eventually swap out all the others to take advantage of the extra capacity and reliability.

Yesterday a second drive failed, the hot spare kicked into action and the array rebuilt.

My goal now is to replace the one failed drive and the two remaining old 1.5TB drives with matching 3TB NAS drives and also migrate to a four drive RAID 6 array rather than the RAID 5 +hot spare.

If I just replace the bad drive first, will that automatically make it the hot spare? Or will I be prompted as to how I want to use the new drive and I can migrate to RAID 6 at that time, then after the migration swap the remaining lower capacity drives one at a time to expand the array?

Thanks!

TS-459 Pro
QTS 4.0.3
2x Seagate 1.5TB ST31500341AS (old drives)
2x Seagate 3TB NAS ST3000VN000 (new drives)

[doktornotor]

Which information on RAID migration are you missing in the fine manual?

http://docs.qnap.com/nas/4.0/Home/en/ra ... gement.htm

[schumaku]

One of the keys - please don't forget:

Note: A hot spare drive must be removed from the disk volume before executing the following action:
• Online RAID capacity expansion
• Online RAID level migration
• Adding a hard drive member to a RAID 5, RAID 6 or RAID 10 volume

Then complete the RAID if it's still degraded by swapping the next broken HDD. Once successfully rebuild - strictly follow the guided RAID migration process. In the slots where you have the new HDD - just remove it, and plug the same HDD back.

[jds580s]

Thanks so much! The migration is in progress, and I appreciate the tip on removing and re-plugging the drives that are already new for the expansion.