Setup Exclusive Read Cache

Overview

This function sets the ratio for an exclusive read cache area in the CM cache memory.

By setting the exclusive read cache area, the read I/O performance may be maintained regardless of the write I/O when the storage system is in a high-load state.

Caution

If exclusive read cache is specified, the I/O performance may be reduced depending on the operating environment. Do not change the default setting ("0 %") for normal use.
Using this function when the storage system load is low is recommended. This function can be used during system operations, but the cache mode is temporarily changed to "Write Through Mode" during a configuration.

Note

The same exclusive read cache area size is secured in all CMs.
If "0 %" is set for "Exclusive Read Cache" or if the calculated value is less than "64MB", "64MB" is secured for each CM.

User Privileges

Availability of Executions in the Default Role

Default role	Availability of executions
Monitor
Admin
StorageAdmin
AccountAdmin
SecurityAdmin
Maintainer

Refer to "User Roles and Policies" for details on the policies and roles.

Settings

Cache Size Settings

Item

Description

Setting values

Exclusive Read Cache

Select the exclusive read cache ratio for the CM cache memory.

The actual capacity of the exclusive read cache varies depending on the memory size installed in the storage system.

Exclusive read cache capacity = Cache area for user data (*1) × Exclusive read cache (%)

*1	:	Cache area for user data = (Memory size per CM - Active table area (such as copy table size)) ÷ 2 (*2)
*2	:	To mirror the user data, divide the calculated value in half.

0 % (Default)

5 %

10 %

15 %

20 %

25 %

30 %

Operating Procedures

Click [Setup Exclusive Read Cache] in [Action].
Select the exclusive read cache, and click the [Set] button.

→ A confirmation screen appears.
Click the [OK] button.

→ The exclusive read cache setting starts.
Click the [Done] button to return to the [System Settings] screen.