You can calculate the number of cache management devices you must reserve to initially create a Thin Image pair for a volume.
For Virtual Storage Platform 5000 series, 8,192 cache management devices are required to create TI pools in a system for the first time. For details about the number of cache management devices required for creating HDP pools, see the Provisioning Guide. Thin Image must reserve 4,096 cache management devices out of 8,192. When you create Thin Image pairs in volumes for the first time, confirm that at least 4,097 cache management devices are reserved. If the number is less than 4,097, pairs might not be created.
For VSP E series, the system can use 65,536 cache management devices.
Use the following formula:
Number of cache management devices that you must reserve = ceil (Size of P-VOL [TB] / 2.6)
If the amount of pool usage for the P-VOL exceeds 70 percent of the total capacity of the cache management devices reserved for the P-VOL, you must reserve another cache management device. You can reserve a maximum of 256 cache management devices for each P-VOL.