There are a number of factors you must consider before creating a snapshot. When you create a snapshot, you must be prepared to provide the following information:
Provide a unique name that identifies the snapshot and enables you to easily identify the primary volume.
When you create a snapshot, you also create a snapshot reserve volume that stores information about the data that has changed since the snapshot was created. Provide a unique name that enables you to easily identify the snapshot to which it corresponds.
You must specify the capacity of the reserve volume as a percentage of the primary volume. You can eliminate the risk of running out of space by setting the reserve volume to the 100% level of activity, indicating that every block will change, for the following reasons:
You can specify the threshold at which the management software generates messages to indicate the level of space left in the reserve volume. By default, the software generates a warning notification when data in the reserve volume reaches 50% of the available capacity. You can monitor the percentage of space used from the Snapshot Details page for the volume snapshot.
If the reserve volume for a snapshot becomes full, the management software can:
A snapshot can be created on a virtual disk as long as the redundant array of independent disks (RAID) level, the number of disks, and the disk type (either Fibre Channel (FC) or Serial Advanced Technology Attachment (SATA)) of the virtual disk match the primary volume's profile. The virtual disk must also have enough capacity for the snapshot.
The following options are available:
You can add the snapshot to an existing storage domain, including the default storage domain, or create a new one by mapping the snapshot to a host or host group. A storage domain is a logical entity used to partition storage that allows a host or host group to have read/write access to the snapshot. The default storage domain contains all hosts and host groups without explicit mappings and enables them to share access to all snapshots that are not explicitly mapped. If you choose to map the snapshot later, the management software automatically includes it in the default storage domain.
Note: A host or host group will be available as a mapping option only if an initiator is associated with each individual host and each host included in a host group.