Hewlett Packard Enterprise HPE XP7, Руководство пользователя, Страница: 65 / 311

Calculate the number of FS pairs that you can create using the following formulas, where SM refers to
shared memory:
Number of FS pairs that you can create =
Snapshot estimated manageable capacity / Snapshot management capacity in a P-VOL
Snapshot estimated manageable capacity in a P-VOL [GB] =
(P-VOL capacity of FS pairs [TB] / 2.6) * 3,024 + (168 * 2 (consumed shared memory [GB]))
More information
Calculating the number of Fast Snap pairs based on pair tables 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
Viewing the list of primary volumes on page 139
Fast Snap cache management device requirements on page 68
Calculating Fast Snap pairs based on cache management devices
Cache management devices are the unit for controlling the cache in association with logical volumes
(LDEVs). They are required to perform FS tasks, such as creating FS pairs for a volume.
To view the number of cache management devices in RWC, see Viewing the number of cache
management devices on page 150.
Use the following formula to calculate the number of FS pairs that you can create based on the number of
cache management devices:
Number of FS pairs that you can create =
Number of cache management devices / ceil (the P-VOL capacity of FS pairs [TB]) / 2.6)
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 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 the number of remaining cache management devices on page 190
Calculating Fast Snap pairs based on cache management devices 65