Hewlett Packard Enterprise HPE XP7, User Manual, Page: 64 / 311

• The number of Fast Snap pairs that you can create based on the number of available pair tables.
• The snapshot estimated manageable capacity.
• The number of cache management devices that you must make available.
The smallest of the three calculations is the maximum number of Fast Snap pairs that you can create in
the storage system.
When you create Fast Snap pairs again, you only need to know the number of pair tables to calculate the
number of pairs that you can create. You do not need to know the snapshot estimated manageable
capacity or the number of cache management devices.
If you have multiple P-VOLs, calculate the number of Fast Snap pairs that you can create for each P-VOL
in the storage system.
Calculating the number of Fast Snap pairs based on pair tables
Pair tables contain information that is required to manage FS pairs. Each FS pair requires one pair table.
The maximum number of pair tables is the maximum number of pairs that can be used in a storage
system.
The number of FS pairs that you can create is maximum-number-of-pair-tables-per-storage-system -
number-of-existing-pairs .
The maximum number of pair tables is 1,048,575.
To view the number of existing FS pairs in RWC, use the Local Replication window. In RAID Manager,
use the
raidcom get snapshot
command. For details, see Viewing local replication summary
information on page 137.
More information
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
Fast Snap cache management device requirements on page 68
Calculating Fast Snap pairs based on the snapshot estimated manageable
capacity
You can calculate the number of FS pairs you can create based on the snapshot estimated manageable
capacity.
To view the snapshot estimated manageable capacity in RWC, see Viewing local replication summary
information on page 137.
64 Calculating the number of Fast Snap pairs based on pair tables