Consider the following when deciding to use snapshots to protect data on virtual volumes.
- Do not enable snapshots for all volumes. Carefully consider what data requires this type of protection and plan accordingly. The maximum number of mappable snapshots per system is 1,024. When the limit is reached, no snapshots can be created until existing snapshots are deleted.
- If replication is enabled between two ME4 Series systems, the replication process creates internal snapshots which are not visible to the administrator. These snapshots do not count against the per-volume limit but do count toward the system limit.
- Snapshots can be created manually, or created by a pre-defined schedule on a per-volume basis.
- It is not possible to define a common snapshot schedule across multiple volumes. Therefore, if a consistent snapshot is required for a group of volumes, manual coordination must be done from applications and through the use of scripting to synchronize and automate the multi-step process.
- Snapshots are treated like any other volumes. They can be mapped to hosts and made read-only or read-write.
- Taking snapshots is fast and efficient. They consume no space initially until data is changed in the snapshots.
- Snapshots are logical copies of the source volumes. They are dependent on the source volumes, and I/Os to the snapshots might affect I/Os to the source volumes. Limit access to the number of copies of snapshots created from the same source volume and monitor performance carefully over time to determine the actual impact to the environment.
See the ME4 Series Administrator's Guide for a detailed description of the features.