Cache management devices manage the cache associated with volumes (LDEVs). Each LDEV requires at least one cache management device. An LDEV that is not a V-VOL requires one cache management device. For an LDEV that is a V-VOL, you need to calculate the number of cache management devices required, which depends on the capacity of the V-VOL (capacity of the user area) and the maximum capacity of the cache management device.
The storage system can manage up to 65,280 cache management devices.
The following table shows the support status of each management tool for the cache management device function.
| Management tool | Support status | Supported DKCMAIN microcode version |
|---|---|---|
| VSP One Block Administrator | No | NA |
| VSP One Block Administrator API | No | NA |
| CCI | Yes | All versions |
| REST API | No | NA |
This table shows the maximum capacity of the cache management device.
| Maximum capacity of cache management device | |
|---|---|
| MB (TB) |
Blocks |
| 3,145,548 MB (2.99 TB) |
6,442,082,304 blocks |
Use this formula to calculate the number of cache management devices that a V-VOL requires. In this formula, the user-specified capacity is the user area capacity of a V-VOL.
- V-VOL
ceiling(user-specified-capacity / max-capacity-of-cache-management-device)
- DRS-VOL
ceiling(user-specified-capacity / max-capacity-of-cache-management-device) + ceiling(user-specified-capacity / max-capacity-of-cache-management-device x 2) x 2
- DRD-VOL with dedupe and compression
ceiling(user-specified-capacity / max-capacity-of-cache-management-device) x 2
where
ceiling: The value enclosed in ceiling( ) must be rounded up to the nearest whole number.
You can view the number of cache management devices by using CCI. This operation is not available by using VSP One Block Administrator, VSP One Block Administrator API, or REST API.