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QTS 5.0.x

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Configuring SSD Cache Settings

  1. Go to Storage & Snapshots > Storage > Cache Acceleration.
  2. Click Manage and then select Settings.

    The Switch SSD Cache window opens.

  3. Select which volumes and LUNs can use the SSD cache.

    For data safety, volumes and LUNs created on an external storage device cannot use the SSD cache if the cache type is Read-write.

  4. Click Next.
  5. Select a cache mode.

    Cache Mode


    Recommended Use Cases

    Random I/O

    Only small data blocks are added to the SSD cache. Larger blocks are accessed directly from regular storage.

    Virtualization, databases

    All I/O

    Small and large data blocks are added to the SSD cache. Both sequential and random I/O requests are accelerated.

    Video streaming, large file access operations


    An HDD RAID group may outperform a SSD RAID group for sequential I/O if the ratio of HDDs to SSDs is 3:1 or greater, and the HDD group has a RAID type of RAID 0, 5, 6, or 10. However, SSDs will always be faster for random I/O. If the NAS contains a RAID group of type RAID 0, 5, 6, or 10 that contains three times more disks than the SSD cache, you should select Random I/O.

  6. Optional: Configure bypass block size.

    This value determines the maximum size of the data blocks that are stored in the SSD cache. Selecting a larger size may improve the cache's hit rate but uses more cache space. The default value is 1 MB.

  7. Click Finish.