Synology NAS - add new drive and change RAID type
Andrew Henderson 
I have DS220+ with 1 3TB drive, and basic raid (no data protection).
I want to add another 3TB drive, and change the RAID type to SHR.
On the storage pool action menu I have no "Add Drive" option, When selecting "Change RAID type" my only option is to apply it to the old drive.
So the right way to do it is to change RAID for my storage pool to 1, than add new drive, than change RAID again to SHR?
No faster way to go from basic to SHR?
2 Answers
SHR is meant to be used to save disk-waste if a more common RAID set is chosen when you have multiple HDD with different storage capacity. Ref:
If you have 2 identical HDD capacity - then there is no point of doing SHR. You might as well go straight into RAID1 (full redundancy).
Edit: Thanks gronostaj - had not considered that upgrade path.
Edit2: Going through Synology forum and KB - I don't see any option available. Do try to reach out to Synology support and see what they say. You can contact them from the Synology DSM - and open the "Contact Support" app - under Storage & Virtualisation - Change RAID type / RAID migration - and see how you go.
1Synology's official answer:
For two-bay NAS model, if you add one more drive to Basic, it can be converted to Raid1 only.
Please refer to the below article:
Only certain RAID types can be changed to other RAID types. It's not allowed to change Basic to SHR by adding drive(s).
If you still want SHR, the only way is to recreate a new SHR volume by the new drive directly, then you can move the data from the basic volume to the new SHR volume. After that, you can remove the basic storage pool, add the drive into the new SHR storage pool.
You will have a SHR storage pool/volume which is assembled with 2 drives, half disk capacity is used for storage capacity, the half capacity is used for disk redundancy. Therefore, the SHR storage pool/volume will be about 1 disk capacity size only.
This is based on SHR mechanism, please refer to below instruction:
