Hewlett Packard Enterprise HPE XP7, User Manual, Page: 69 / 311

Task Number of cache management devices
required
Create a P-VOL. 256
Initially create an FS pair for a volume. 4,097
The number of cache management devices that can be used in a system is 65,280.
More information
Calculating the number of Fast Snap pairs based on pair tables on page 64
Calculating Fast Snap pairs based on the snapshot estimated manageable capacity on page 64
Calculating Fast Snap pairs based on cache management devices on page 65
Calculating the number of cache management devices on page 66
Calculating the Fast Snap pair capacity for THP pools on page 66
Calculating and assigning pool capacity on page 69
External Storage and external volumes used as pool-VOLs on page 71
Simultaneous processing of multiple Fast Snap pair tasks on page 71
Pair operations when pairs are cascaded on page 72
Pair operations when pairs are not cascaded on page 83
Pair operations when a P-VOL is shared by multiple S-VOLs on page 84
Data recovery and backup differences between Fast Snap and Business Copy on page 85
Calculating and assigning pool capacity
Use the following formula to calculate the capacity of the snapshot data that you can store in the Fast
Snap pool:
Capacity of the snapshot data that you can store in the pool =
Total capacity of pool-VOLs in the pool - Capacity of V-VOL management areas
The capacity of V-VOL management areas is 3% of the pool capacity.
Use the following formula to calculate the capacity of the snapshot data that you can store in the THP
pool:
Capacity of the snapshot data that you can store in the pool =
Total capacity of pool-VOLs in the pool - (Capacity of pool VOLs used by THP V-VOLs +
Capacity of V-VOL management areas)
Use the following formula to calculate the pool capacity:
Capacity of the pool [MB] =
Total number of pages * 42 - 4200
Use the following formula to calculate the total number of pages:
Total number of pages =
Sigma (floor (floor (pool-VOL number of blocks / 512) / 168)) for each pool-VOL
Calculating and assigning pool capacity 69