Repair M.2 RAID 1 in internal M.2 slots

The following was tested on a DS1821+. It may not work on older models.

Requires DSM 7.2 or later.

Repair NVMe RAID 1 in internal M.2 slots.

1. Deactivate crashed NVMe drive.
2. Shut down Synology.
3. Replace deactivated drive.
4. Boot Synology.
5. Run Synology_HDD_db.
6. Open Storage Manager.
7. Click "repair now" on the M.2 storage pool and select the unused NVMe drive.