Change the RAID Type of a Storage Pool
Storage pools can be changed from one RAID type to another without losing existing data. For example, you can create a RAID 1 storage pool on your Synology NAS and later change it to RAID 5 if you install more drives. This article provides instructions on changing the RAID type of existing storage pools on your Synology NAS.
Note:
- We recommend using drives that are compatible with your Synology NAS and are on the Synology Products Compatibility List. Using drives not on the list may affect system stability and result in data loss.
- If you need to add or remove an M.2 SSD from your Synology NAS, make sure you do so when the system is completely powered off. Refer to the product manual of your NAS model for specific instructions.
Drive Requirements
To change the RAID type of a storage pool, you must have a sufficient number of available drives installed in your Synology NAS. The table below shows the minimum number of drives required for each RAID type.
| RAID Type | Minimum Number of Drives Required |
|---|---|
| RAID 1 | 2 |
| RAID 5 | 3 |
| RAID 6 | 4 |
| SHR-2 | 4 or 5 (depending on the drive configuration of SHR-1) |
RAID Type Requirements and Limitations
Only certain RAID types can be changed to other RAID types. For example, RAID 1 can be changed to RAID 5, but RAID 5 cannot be changed to RAID 1. Refer to the table below for details.
| Current RAID Type | Possible Conversion Target Type | Additional Number of Drives Required |
|---|---|---|
| Basic | RAID 1 | 1 |
| Basic | RAID 5 | 2 |
| RAID 1 | RAID 5 | 1 |
| RAID 5 | RAID 6 | 1 |
| SHR-1 | SHR-2 | 1 or 2 (depending on the drive configuration of SHR) |
Note:
- Learn more about choosing a RAID type.
- Learn more about Synology Hybrid RAID (SHR).
- Use the RAID Calculator to estimate space utilization.
- An SHR-1 storage pool with the following drive configurations may require two additional drives when changed to an SHR-2 storage pool:
- The storage pool contains only two drives.
- All drives have different capacities.
- In a RAID array comprising three or more drives, the capacity of the two largest drives is larger than that of the other drives.
- Some Synology NAS models do not support changing a RAID 5 storage pool to a RAID 6 storage pool.
- Some Synology NAS models do not support changing RAID types when the storage pool contains drives that are not on the Synology Products Compatibility List.
Change the RAID Type
Before you start:
- Make sure the status of your storage pool is Healthy.
- When adding new drives to a storage pool, the new drives must be larger than or equal to the smallest drive in the storage pool and all drives must be of the same drive type.
- The RAID type of RAID arrays in a RAID Group cannot be changed. The RAID Group feature is available on specific models only.
To change the RAID type of a storage pool:
- Go to Storage Manager > Storage.
- Select the storage pool whose RAID type you want to change. Then, click the upper-right
icon and select Change RAID Type. - Select the RAID type you want to change to and click Next.
Note: Only the RAID type that can be changed to will be listed. For example, if you want to change the RAID type of a RAID 1 storage pool, only RAID 5 will be listed. - Select the drives you want to add to the storage pool and click Next.
Note: All data on the newly added drives will be erased. Make sure to back up your data in advance. - Confirm the settings and click Apply to finish.
During the conversion process, the status of the storage pool will change to Changing RAID type. Once the conversion is complete, the storage pool status will return to Healthy. You can click the upper-right 
icon of the storage pool to view its current RAID type.
Note:
- If issues occur to a drive during the process, the RAID type can still be changed but the storage pool status will become Degraded once the process is complete.
- The Change RAID Type option only appears when all the following criteria are met:
- The current RAID type of the storage pool can be changed.
- The storage pool does not contain any RAID Group.
- If the Change RAID Type option cannot be selected, refer to this article for troubleshooting steps.