Release Notes

50 Dell Virtual Storage Manager: Installation Considerations and Local Data Protection | 2079-BP-V-VSM
7 Local data protection strategies with vVol datastores
Virtual Volumes significantly changes taking snapshots. Traditional VMware snapshots, its delta VMDKs, and its
associated limitations have been replaced by SAN-based traditional volume snapshots. This provides a number of
benefits:
• Individual virtual machine snapshots
• Instant creation of virtual machine snapshots
• Snapshots that can be kept indefinitely
• Instant restoration of a virtual machine from a snapshot
7.1 Comparing VMFS and vVol data protection
With traditional VMFS datastores, there are two snapshot options:
• Traditional VMware snapshots:
- Use familiar vSphere GUI
- Perform per-virtual-machine snapshots
- Use best practices that limit the number of snapshots
- Use best practices that limit how long snapshots should be kept
- Can impact performance
- May take a long time to restore
- Offer application consistency
Note SAN-based snapshots by themselves are unaware of the target snapshot data on the volume, and therefore
create crash-consistent snapshots. However, when combined with host-side tools from the PS Series Host Integration
Tools (HIT) kits, like VSM, they become application aware, and can create application consistent snapshots.
• PS Series SAN snapshots with VSM:
- Use the Dell VSM plugin to vSphere
- Take snapshots of an entire datastore of virtual machines
- Take snapshots which can be kept indefinitely
- Cause no performance impact
- Perform rollback restores quickly, but roll back all virtual machines on the volume
- May take a long time to perform selective restores
- Offer application consistency
Traditional VMware snapshots and VSM snapshots both have their particular use cases in addition to pros and cons.
Virtual Volumes combines the best features of both into one technology:
• Use native vSphere GUI
• Provide granular, per-virtual-machine snapshots
• Instantly create and restore