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SSD Cache feature

The SSD Cache feature improves read-only performance. SSD cache is a set of solid-state disks (SSDs) that you logically group together in your storage array.

SSD cache is a secondary cache for use with the primary cache in the controller DRAM. In controller cache, the data is stored in DRAM after a host read. In SSD cache, the data is copied from user-specified base volumes, and stored on two internal RAID volumes (one per controller) that are automatically created on the SSDs when you create an SSD cache. These volumes are used for internal cache processing purposes. These volumes are not accessible or appear in the user interface. However, these two volumes do count against the total number of volumes allowed in the storage array.

Note: The SSD Cache feature is available only when the SSD Cache feature is configured, an SSD cache entity is created, and each base volume for which you want to use the SSD cache has the SSD cache attributes enabled.

Using high performance SSDs to cache the data from the base volumes improves the application I/O performance and response times, and delivers sustained performance improvement across different workloads, especially for high-IOP workloads. Simple volume I/O mechanisms are used to move data to and from the SSD cache. After data is cached and stored on the SSDs, subsequent reads of that data are performed on the SSD cache, there by eliminating the need to access the base volume.

Note: The SSD read cache can be secure with a non-secure base volume or a secure base volume (either FDE or FIPS). However, when there is a FIPS-secure base volume, the storage management software alerts you that the SSD read cache does not have the same security capabilities as the base volume. You can only enable security on the SSD read cache volume at the time it is created.
For more information about the SSD Cache feature, refer to the following: