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Knowledge Center

Add Drives to Expand the Storage Pool Capacity

This article guides you through how to expand an existing storage pool by installing additional drives. As long as there are empty drive slots in your Synology NAS, you can install additional drives and add them to a storage pool for capacity expansion.

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 Synology NAS model for specific instructions.

RAID type requirements:

For the Add Drive option to be available, your storage pool needs to be in one of the following RAID types:

  • JBOD
  • RAID 5
  • RAID 6
  • RAID F1
  • Synology Hybrid RAID (SHR) consisting of at least two drives
  • RAID 1
    Note: Adding drives to a RAID 1 storage pool does not increase its storage capacity. This action only adds mirror drives to the storage pool for increased fault tolerance.

Drive requirements:

For the Add Drive option to be available, your Synology NAS needs to contain at least one drive that is not in use and meets the following requirements:

  • Drive status: The drive must be Healthy.
  • Drive type: The drive must be of the same drive type. Using drives of different types will affect system reliability and performance. Mixed drive types as shown below are not supported:
    • HDDs and SSDs
    • SATA and SAS drives
    • 4K native and non-4K native drives
  • Drive size:
    • For SHR: The drive you want to add must be equal to or larger than the largest drive in the storage pool, or equal to any of the drives in the storage pool.
      For example: If an SHR storage pool is composed of three drives (2 TB, 1.5 TB, and 1 TB), we recommend the newly-added drive to be at least 2 TB for better capacity usage. You can also consider using 1.5 TB and 1 TB drives, but note that some capacity of the 2 TB drive will remain unused.
    • For RAID 1, RAID 5, RAID 6, or RAID F1: The drive you want to add must be equal to or larger than the smallest drive in the storage pool.
      For example: If a RAID 5 storage pool is composed of three drives (2 TB, 1.5 TB, and 1 TB), we recommend the newly-added drive to be at least 1 TB.

To view detailed information about the installed drives, check Storage Manager > HDD/SSD.

Note:

To add drives to a storage pool:

  1. Make sure the storage pool you want to expand is in Healthy status. If it is not, follow the Suggestion shown to resolve the issue first.
  2. Shut down your Synology NAS.
    Skip this step and go to step 5 if your Synology NAS supports hot-swapping.
  3. Insert a new drive into an empty drive slot.
    For drive installation instructions, refer to the product manual of your Synology NAS model.
  4. Start up your Synology NAS.
  5. Go to Storage Manager > Storage.
  6. Click the upper-right icon of the storage pool you want to expand.
  7. Select Add Drive from the drop-down menu.
  8. Select the drives you want to add. Only drives that meet the drive requirements are listed.
  9. Follow the wizard to finish.

Note:

  • The Add Drive option becomes unavailable when: all drives are in use, no available drives meet the drive requirements, the storage pool status is not Healthy, or the RAID type of the storage pool does not meet the RAID type requirements. For more information, refer to this article.

To expand the volume size:

Once a storage pool contains sufficient capacity, the size of its corresponding volume can be expanded either automatically or manually, depending on the storage pool type.

  • Single-volume storage pool: For a storage pool that supports a single volume, the volume size will be expanded automatically once the storage pool capacity has been expanded. For details, refer to To add a drive to a storage pool.
  • Multiple-volume storage pool: For a storage pool that supports multiple volumes, the volume size can be expanded manually once the storage pool contains sufficient capacity. For details, refer to Expand the Volume Size.

Note:

  • Starting from DSM 7.0, all newly created storage pools come with multiple-volume support, thereby providing higher flexibility. You can choose to create one or multiple volumes in a single storage pool and allocate different capacities for each volume.