When drive errors occur, some of the following symptoms may appear:

• The Drive reconnection count¹ shows a value other than 0.
  1. Go to Storage Manager > HDD/SSD.
  2. Select the suspected failed drive.
  3. Click Health Info.
  4. Check the Statistics section for the Drive reconnection count.
• Storage Manager shows I/O errors in the Logs.
  1. Go to Storage Manager > HDD/SSD > Logs.
  2. Look for the following log messages: I/O errors, Drive plugged in, or Drive plugged out.
• The system sends you the Drive reconnection (ICRC error) alert.
  1. Check your email or the notifications on the DSM desktop.
  2. Look for the Drive reconnection (ICRC error) alert.

The following sections will help you identify if the problem is with the drive or the drive slot.

DSM 6.2 to 7.2¹

• Check the drive reconnection count graph
• Swap the drives for testing
• Replace the defective drive

Check the drive reconnection count graph

Monitor whether the drive reconnection count is increasing.

1. Go to Storage Manager > HDD/SSD.
2. Select the suspected failed drive.
3. Click Health Info. Go to History > Key Information of Drives.
4. Check the Drive reconnection count graph.
   • If the count is increasing, refer to the Swap the drives for testing section to conduct more testing.
   • If the count is stable, continue to monitor the drive. The drive might have been removed and reinserted, causing a slight increase to occur.

Swap the drives for testing

Check if the issue follows the drive or remains with the drive slot.

For models in a high-availability cluster:

1. Remove and replace the suspected failed drive. (Tutorial)
2. Continue to monitor the drive reconnection count.
   • If the count is increasing rapidly, the issue may be with the drive slot. We recommend backing up all your data and replacing your Synology NAS.
   • If the count is stable, the issue may be with the suspected failed drive you just replaced.

For one-bay models:

1. Back up all your data. (Tutorial)
2. Power off your Synology NAS.
3. Remove the suspected failed drive² and replace it with a healthy compatible drive.
4. Power on your Synology NAS.
5. Install DSM. (Tutorial)
6. Create a new storage pool and volume.
7. Restore the backed up data to the storage pool and volume. (Tutorial)
8. Go to Storage Manager > HDD/SSD.
9. Select the healthy compatible drive to check.
10. Click Health Info. Go to History > Key Information of Drives.
11. Check the Drive reconnection count graph.
    • If the count is increasing, the issue may be with the drive slot. We recommend backing up all your data and replacing your Synology NAS.
    • If the count is stable, the issue may be with the suspected failed drive you just replaced.

For multi-bay models:

1. Make sure all the storage pools are in a Healthy status.³
2. Power off your Synology NAS.
3. Remove the suspected failed drive² and insert it into a functioning empty drive slot. If there is no empty drive slot on your Synology NAS, swap the drive with another healthy drive on the same Synology NAS.
4. Power on your Synology NAS.
5. Go to Storage Manager > HDD/SSD.
6. Do the following for both the suspected failed drive and the healthy drive in the suspected failed drive slot:
   1. Select the drive you want to check.
   2. Click Health Info. Go to History > Key Information of Drives.
   3. Check the Drive reconnection count graph:
      • If the count is increasing for the suspected failed drive, the issue may be with the drive. We recommend replacing the drive to avoid possible data loss. You can refer to the Replace the defective drive section for more information.
      • If the count is increasing for the healthy drive in the suspected failed drive slot, the issue may be with the drive slot. We recommend backing up all your data and replacing your Synology NAS.

For expansion units:

1. Make sure all the storage pools are in a Healthy status.³
2. Power off your Synology NAS.
3. Remove the suspected failed drive² and insert it into a functioning empty drive slot. If there is no empty drive slot on your expansion unit, swap the drive with another healthy drive on the expansion unit.
4. Power on your Synology NAS.
5. Go to Storage Manager > HDD/SSD.
6. Do the following for both the suspected failed drive and the healthy drive in the suspected failed drive slot:
   1. Select the drive you want to check.
   2. Click Health Info. Go to History > Key Information of Drives.
   3. Check the Drive reconnection count graph:
      • If the count is increasing for the suspected failed drive, the issue may be with the drive. We recommend replacing the drive to avoid possible data loss. You can refer to the Replace the defective drive section for more information.
      • If the count is increasing for the healthy drive in the suspected failed drive slot, the issue may be with the drive slot or the expansion unit cable. We recommend replacing the expansion unit cable and continuing to monitor the Drive reconnection count.

Replace the defective drive

Check the Synology Products Compatibility List to ensure the replacement drive is compatible with your Synology NAS model.

For RAID types without data protection:

1. Back up all your data. (Tutorial)
2. Power off your Synology NAS.
3. Remove and replace the defective drive.²
4. Power on your Synology NAS.
   • Install DSM if your Synology NAS is a one-bay model. (Tutorial)
5. Create a new storage pool and volume.
6. Restore the backed up data to the storage pool and volume. (Tutorial)

For RAID types with data protection:

Remove and replace the defective drive.² Then, repair the storage pool. For detailed steps on repairing the storage pool, refer to the respective help article for DSM 7 and DSM 6.2.