HP XP P9500 Storage - Manual (Page 30)

Notes on consistency groups
•
(If you are using RAID Manager to create snapshots) To avoid the raidcom add snapshot
command from being rejected, define an FS pair that shares the same P-VOL in the separate
consistency groups.
•
(If you are using RAID Manager to split pairs defined in consistency groups) To avoid the
pairsplit
command from finishing abnormally and to guarantee that the P-VOL snapshot
data is stored when the VSP receives the command, assign pairs defined in consistency groups
and pairs not defined in consistency groups to separate groups defined by RAID Manager’s
configuration definition file (this group is not a consistency group).
•
You can only specify one consistency group for a group defined by RAID Manager’s
configuration definition file.
To create pairs using a group defined by RAID Manager’s configuration definition file, and
if a pair with a consistency group specified is already created in the group, the addition will
be made to the same consistency group even if you try to create a new pair with a different
consistency group specified.
To specify multiple consistency groups, define the same number of groups using RAID
Manager’s configuration definition file.
Requirements for snapshot groups
The following table explains requirements for snapshot groups.
Description Item
Up to 32 characters. Once you create a snapshot group, you cannot change
its name. Name
Maximum number •
The maximum number of snapshot groups for a storage system is 512.
• The maximum number of FS pairs for a snapshot group is 8,192.
Requirements for Fast Snap tasks
This section discusses points to be considered regarding FS tasks.
Calculating the number of virtual volumes that the storage system can create
Use the following formula to calculate the maximum number of V-VOLs that the storage system can
create:
The maximum number of V-VOLs = 58,800* - (The number of external volumes
+ The number of P-VOLs for FS pairs)
* Your system configuration determines the maximum value in this formula.
Calculating the number of Fast Snap pairs
When you create FS pairs for a P-VOL for the first time, the number of FS pairs that you can create
in a storage system depends on the following:
•
The number of differential tables.
•
The number of pair tables.
•
The snapshot estimated manageable capacity.
•
The number of cache management devices.
To calculate the number of FS pairs that you can create, complete the following:
30 Planning and design