If your SSD cache is running low on storage capacity, it indicates that the amount of hot data (i.e., most frequently accessed data) for the SSD cache to store is about to exceed the allocated cache size. Although an insufficient SSD cache size will not affect the operation of your Synology NAS, you may still want to expand the allocated size for better system performance.

This article will guide you through determining the optimal SSD cache size and provide a workaround for expanding the allocated size of your SSD cache.

Determine the optimal SSD cache size

You can let SSD Cache Advisor recommend a suitable SSD cache size based on its analysis of your current data usage pattern. Please refer to the help articles for DSM 7.0 and DSM 6.2, respectively, for the detailed instructions.

Expand the allocated size of an SSD cache

You cannot directly modify the allocated size of an SSD cache after it has been created. If you want to increase the allocated size of an existing SSD cache, the workaround is to remove it¹ and then create a new SSD cache. Do the following according to your DSM version:

• DSM 7.0 and above:
  1. Go to Storage Manager > Storage and select the SSD cache to remove.
  2. Click > Remove to permanently remove the SSD cache.²
  3. Power off your Synology NAS.
  4. Physically remove the SSDs from your Synology NAS and replace them with ones of a larger capacity.³
  5. Power on your Synology NAS.
  6. Return to Storage Manager > Storage.
  7. Click Create > Create SSD Cache to create a new SSD cache.
  8. Follow the wizard to finish.
• DSM 6.2 and below:
  1. Go to Storage Manager > SSD Cache and select the SSD cache to remove.
  2. Click Remove to permanently remove the SSD cache.²
  3. Power off your Synology NAS.
  4. Physically remove the SSDs from your Synology NAS and replace them with ones of a larger capacity.³
  5. Power on your Synology NAS.
  6. Return to Storage Manager > SSD Cache.
  7. Click Create to create a new SSD cache.
  8. Follow the wizard to finish.