Hewlett Packard Enterprise HPE XP7, User Manual, Page: 71 / 311

If multiple snapshot data are stored, the data may be shared in a pool. In this case, you can release Fast
Snap pairs, but the snapshot data cannot be deleted from the pool. If you release all Fast Snap pairs that
have snapshot data containing the shared data, the snapshot data are also deleted from the pool.
Creating a backup of data
During creation of a backup copy, a significant amount of data is read from the secondary volume. This
may increase the accesses to the primary volume and degrade the host I/O performance.
Procedure
1. Store the snapshot data, or clone pairs.
2. Use an S-VOL.
More information
Splitting Fast Snap pairs to store snapshot data on page 120
External Storage and external volumes used as pool-VOLs
In Ext Stor, an XP7 Storage system is referred to as a local storage system, and the other storage
systems are referred to as external storage systems. With Ext Stor installed, you can use external and
internal volumes as pool-VOLs. Volumes in local storage systems are referred to as internal volumes, and
volumes in external storage systems are referred to as external volumes.
NOTE: Using external volumes increases the likelihood of a failure, and disaster recovery is more
complex and challenging. Using multiple external volumes as pool-VOLs in a pool increases the likelihood
of the pool being blocked.
To minimize the adverse effects of failure, use only one pool per external storage system. An external
pool-VOL that is blocked due to a failure blocks the pool. You must restore blocked pools.
For more information about external storage systems and disaster recovery methods for external
volumes, see the
HPE XP7 External Storage for Open and Mainframe Systems User Guide .
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
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
Simultaneous processing of multiple Fast Snap pair tasks
For each of the following pair tasks, the number of simultaneous instances processed in the background
is equal to the total number of MP blades in the storage system:
Creating a backup of data 71