Replace a Drive

You can use the Replace Drive feature to replace a drive in your Synology NAS to prevent storage pool degradation or expand the storage pool capacity.

• Replacing a defective drive with a healthy drive can prevent a storage pool from becoming degraded.
• Replacing an existing drive with a larger drive allows the storage pool capacity to be expanded.

When a drive is being replaced using the Replace Drive feature, the corresponding storage pool and data will still be protected by data redundancy throughout the replacement process.

Before You Start

• Use the RAID Calculator to see if replacing a drive will impact the capacity of your storage pool.
• The Replace Drive button only appears when all the following criteria are met:
  • Your Synology NAS must contain at least one unused drive.
  • Your storage pool must be in one of the following RAID configurations: SHR, SHR-2, RAID 1, RAID 5, RAID 6, RAID 10, or RAID F1.
  • Your storage pool must be composed of at least two drives.
• A replacement drive can only replace a drive of the same type. For example:
  • A SATA drive can only replace a SATA drive; a SAS drive can only replace a SAS drive.
  • A 4K native drive can only replace a 4K native drive; a non-4K native drive can only replace a non-4K native drive.
  • A HDD can only replace a HDD; an SSD can only replace an SSD.
• Only one drive can be replaced at a time.

Replace a Drive to Prevent Storage Pool Degradation

A defective drive may result in storage pool degradation and loss of data redundancy. To prevent a storage pool from becoming degraded, the Replace Drive feature allows you to instantly replace a drive in a storage pool whenever drive issues are detected.

To replace a drive:

1. Go to Storage Manager > Storage.
2. Click the upper-right icon of the storage pool whose drive you want to replace.
3. Select Replace Drive.
   If the unused drives in your Synology NAS cannot serve as replacement drives, a message box will appear and inform you of the reasons and suggestions.
4. Select the drive you want to remove from the storage pool and click Next.
5. Select the drive you want to add to the storage pool and click Next.
6. Confirm that you understand that all data on the newly added drive will be erased, and click OK.
7. Confirm the settings and click Apply.

During the replacement process, the storage pool status will change to Replacing. Once the process is complete, the storage pool will return to its original status, and the replaced drive will become deactivated. You can follow the LED drive indicator on your Synology NAS to remove the deactivated drive.

Replace a Drive to Expand Storage Pool Capacity

The capacity of a storage pool can be expanded by replacing a current drive with a larger drive. If a storage pool supports data scrubbing, we recommend performing data scrubbing beforehand to make sure the volume and storage pool are in Healthy status. Before you replace a drive for storage pool expansion, note the following according to the RAID type of your storage pool.

For SHR:

Because SHR storage pools optimize storage capacity based on the number and size of the installed drives, refer to the following to properly expand the storage pool capacity:

• If the existing drives are of the same size, then you must replace at least two drives with two larger drives to expand the storage pool capacity. For example, if your SHR storage pool is composed of three 2 TB drives, then you must replace at least two drives to expand the storage pool capacity.
• If the existing drives are of different sizes, then the replacement drive must be equal to or larger than the largest existing drive. You must replace the smaller drives first to optimize the usage of storage pool capacity. For example, if your SHR storage pool consists of three drives of different sizes (i.e., 4 TB, 3 TB, and 2 TB), then the replacement drive must be at least 4 TB. Replace the 3 TB or 2 TB drives first.

For RAID 1, RAID 5, RAID 6, RAID 10, and RAID F1:

When replacing the drives of a storage pool in RAID 1, RAID 5, RAID 6, RAID 10, or RAID F1 configuration, the smallest drive should always be replaced first to maximize drive usage. The capacity of a storage pool in each RAID type is as follows:

• RAID 1: (smallest drive size)
• RAID 5: (number of drives – 1) x (smallest drive size)
• RAID 6: (number of drives – 2) x (smallest drive size)
• RAID 10: (number of drives / 2) x (smallest drive size)
• RAID F1: (number of drives – 1) x (smallest drive size)

For example, if your RAID 5 storage pool is composed of three drives of different sizes (i.e., 4 TB, 3 TB, and 2 TB), then the available storage pool capacity is 4 TB. If you replace the 4 TB drive or the 3 TB drive, the storage pool capacity will not be changed. To expand the storage pool capacity, the 2 TB drive must be replaced first.

To replace a drive:

1. Go to Storage Manager > Storage.
2. Click the upper-right icon of the storage pool you want to expand.
3. Select Replace Drive.
   If the unused drives in your Synology NAS cannot serve as replacement drives, a message box will appear and inform you of the reasons and suggestions.
4. Check which drive has the smallest capacity and remove it from the storage pool. Click Next.
5. Select the drive you want to add to the storage pool. Click Next.
6. Confirm that you understand that all data on the newly added drive will be erased, and click OK.
7. Confirm the settings and click Apply.

During the replacement process, the storage pool status will change to Replacing. Once the process is complete:

• The storage pool will return to its original status.
• You can go to the corresponding storage pool on the Storage page and check if the capacity has expanded.
• The replaced drive will become deactivated. You can follow the LED drive indicator on your Synology NAS to remove the deactivated drive.

To replace a drive (when there are no unused drives or empty drive slots):

If your Synology NAS does not contain any unused drives or there are no empty drive slots for installing replacement drives, you can perform the following steps instead. We provide an example of replacing the drives of an SHR storage pool in the steps below.

1. Go to Storage Manager > Storage.
2. Click the upper-right icon of the storage pool you want to expand. This expands the storage pool information.
3. Go to the Drive Info section to find out which drive has the smallest capacity.
4. Deactivate the smallest of the member drives:
   1. Go to the HDD/SSD page.
   2. Select the drive.
   3. Click Action > Deactivate Drive.
5. Power off your Synology NAS.
   Skip this step if your Synology NAS supports hot-swapping.
6. Remove the smallest of the member drives and install a new, larger drive.
7. Power on your Synology NAS.
8. Go to Storage Manager > HDD/SSD to make sure the new drive is recognized.
9. Return to the Storage page.
10. Repair the storage pool, which should now be in a Degraded status.
    1. Click the upper-right icon of the storage pool and select Repair.
    2. Select the replacement drive to add to the storage pool.
    3. Follow the wizard to finish.
11. Repeat the above process until all desired drives have been replaced with larger ones.