IBM System Storage DS3000, Programming Manual

Page: 149 / 652

Create SSD cache
This command creates a read cache for a storage subsystem using Solid State Disks (SSDs). Using high
performance SSDs to cache read data improves the application I/O performance and response times, and
delivers sustained performance improvement across different workloads, especially for high-IOP
workloads. Performance Read Cache maximizes the use of expensive fast SSDs.
Performance Read Cache works in addition to the primary cache in the controller DRAM. With controller
cache, the data is stored in DRAM after a host read. With Performance Read Cache, the data is copied
from user-specified base logical drives, and then cached on SSDs.
Syntax
create performanceReadCache userLabel="performanceReadCacheName"
drives=(enclosureID1,drawerID1,slotID1 ...
enclosureIDn,drawerIDn,slotIDn)
[updateExistinglogicalDrives=(TRUE|FALSE)]
Parameters
Parameter Description
userLabel The alphanumeric identifier (including - and _) that you
want to name the new Performance Read Cache. Enclose
the identifier in double quotation marks (" "). You can
use any combination of alphanumeric characters,
underscore (_), hyphen (-), and pound (#) for the
identifier. Identifiers can have a maximum of 30
characters.
drives
The drives that you want to use to create the
Performance Read Cache. For high-capacity drive
enclosures, specify the enclosure ID value, the drawer ID
value, and the slot ID value for each drive that you want
to assign to the Performance Read Cache. For
low-capacity drive enclosures, specify the enclosure ID
value and the slot ID value for each drive that you
assign to the Performance Read Cache.
v
Enclosure ID values are
0
to
99
v
Drawer ID values are
1
to
5
v
Slot ID values are
1
to
32
Enclose the enclosure ID values, the drawer ID values,
and the slot ID values in parentheses.
updateExistinglogicalDrives This optional parameter specifies whether the
Performance Read Cache should be enabled for all
existing logical drives in the storage subsystem. To
enable the Performance Read Cache for all existing
logical drives, set this parameter to
TRUE.
If you want to
enable the Performance Read Cache for individual logical
drives later, set this parameter to
FALSE
. The default value
is
TRUE
.
Notes
A storage subsystem can have only one Performance Read Cache.
Chapter 3. Script Commands
3-103