Extreme Cache Pool; Figure 26 Extreme Cache Pool - Fujitsu ETERNUS DX S5 Series Design Manual

2. Basic Functions
Operations Optimization (Virtualization/Automated Storage Tiering)

Extreme Cache Pool

The Extreme Cache Pool function uses 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 SSDs specified as Extreme Cache Pools.
When a read request is issued from the server, data is read from the faster SSD to speed up the response.
Figure 26 Extreme Cache Pool
When there is a read
request, the response
for the request will be
faster by reading data
from the SSDs instead
of reading data from
the disks.
Specify one SSD to use as an Extreme Cache Pool for each controller.
800GB SSDs can be used for Extreme Cache Pools. Value SSDs and FIPS-compliant Self Encrypting Drives cannot
be used.
A RAID group (RAID0) that is dedicated to the Extreme Cache Pool is configured with the specified 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. 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 800GB 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, or volumes that are configured with SSDs.
One volume for the Extreme Cache Pool is created for each controller.
Caution
• SSDs that are already in use cannot be specified for Extreme Cache Pools.
• The Extreme Cache Pool function may improve random I/O.
Read request
Cache memory
Extreme Cache Pool (SSDs)
73
ETERNUS DX
Controller
Disks
Frequently accessed
areas are written to
the Extreme Cache
Pool (SSDs)
Design Guide