QNAP

QuTS hero 5.0.x

Creating the SSD Cache

Note:

ZFS ensure that files are sequentially written to the cache, so SSD over-provisioning is not required.

  1. Go to Storage & Snapshots > Storage > Cache Acceleration.
  2. Click .

    The SSD Cache Introduction window opens.

  3. Click Start.

    The Create SSD Cache window opens.

  4. Select a cache type.

    Cache Type

    Description

    Create SSD cache for read and write

    QuTS hero creates a combined read cache and write log, which requires fewer SSDs in total.

    Note:

    This setting requires an even number of SSDs.

    Create SSD cache for read or write

    QuTS hero creates a read cache or a write log separately, which makes each cache more effective.

    Note:

    This setting requires at least 1 SSD for creating the read cache, and at least 2 SSDs or an even number of SSDs for creating the write log.
    Important:

    You cannot change the cache type after the cache has been created. To change the cache type, you must remove and then recreate the SSD cache.

  5. Click Next.
  6. Select whether to create a read cache or a write log.
    Note:

    This option is only available if you previously selected Create SSD cache for read or write.

  7. Select one or more SSDs.
    Warning:

    All data on the selected disks will be deleted.

  8. Click Next.
  9. Select which shared folders and LUNs can use the read cache.
    Note:

    This option is only available if you are creating a read cache or a combined read cache and write log.

    Tip:

    This list can be modified later.

  10. Select which storage pools can use the write log.
    Note:

    This option is only available if you are creating a write log or a combined read cache and write log.

    Tip:

    This list can be modified later.

  11. Click Next.
  12. Select a cache mode.
    Note:

    This option is only available if you are creating a read cache or a combined read cache and write log.

    Cache Mode

    Description

    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
    Tip:

    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.

  13. Click Next.
  14. Review the summary information.
  15. Click Create.

    A confirmation message appears.

  16. Select I understand and then click OK.