Extreme Cache Pool

The Extreme Cache Pool function uses NVMe SSDs in enclosures as the secondary cache to improve the read access performance from the server.

Frequently accessed areas are written asynchronously with I/Os to the NVMe SSDs specified as Extreme Cache Pools. When a read request is issued from the server, data is read from the faster NVMe SSD to speed up the response.

Figure: Extreme Cache Pool

Up to four NVMe SSDs (3.2TB) used as an Extreme Cache Pool can be specified for each controller and the installation location is not restricted. Installation is possible in either the controller enclosure or 2.5" NVMe type drive enclosure. SAS SSDs cannot be used.

A RAID group (RAID0) that is dedicated to the Extreme Cache Pool is configured with the specified NVMe SSDs, and volumes for the Extreme Cache Pool are crated in the RAID group.

When using the Extreme Cache Pool as the secondary cache for encrypted volumes, encrypt the Extreme Cache Pool using the firmware data encryption function or select a self-encrypting drive (3.2TB NVMe SSD SED) as a configured drive when creating an Extreme Cache Pool. The firmware data encryption function can be used only if the encryption mode of the ETERNUS DX is enabled.

The capacity that can be used as an Extreme Cache Pool is up to 12.8TB for each controller.

The Extreme Cache Pool function can be enabled or disabled for each volume. Note that the Extreme Cache Pool function cannot be enabled for Deduplication/Compression Volumes, volumes that are configured with NVMe SSDs/NVMe SSD SEDs, or volumes that are configured with SAS SSDs/SAS SSD SEDs.

Up to four volumes for the Extreme Cache Pool are created for each controller.

For details on the installation conditions of Extreme Cache Pool, refer to Drive.

Table: Maximum Installed Number of Extreme Cache Pools and Their Maximum Capacity

Item

ETERNUS DX600 S6

ETERNUS DX900 S6

ETERNUS DX8900 S6

Maximum installed number of Extreme Cache Pools (per storage system)

8

16

96

Maximum Extreme Cache Pool capacity

25.6TB

51.2TB

307.2TB
Caution

  • NVMe SSDs that are already in use cannot be specified for Extreme Cache Pools.

  • The Extreme Cache Pool function may improve random I/O.