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VMware's vSphere Data Protection (VDP) is an agentless virtual appliance which includes deduplication for efficient backup storage utilization, handles changed block tracking to speed backup cycles, supports full VM and file-level restores, and protects VMs that are even powered off.
VDP appliances are designed to reduce storage requirements by applying data deduplication, but deduplication only works when common blocks are present. This means the VDP appliance will usually fill quickly over the short term because many blocks may contain unique data.
Deduplication won't really start to mitigate storage requirements until similar VMs are protected, or until the same VMs have been backed up at least once. For example, if you backup a single VM for the first time, there is little benefit to deduplication. However, as similar VMs are protected, some identical blocks may reduce storage demands, and repeated backups of the same VMs should require only storage for changed blocks.
As more content is protected more frequently, data deduplication will be more effective. Subsequent backups will require very little added storage while aging data is purged. Eventually, VDP storage requirements should approach a point where the new data stored is about equal to the amount of the old data deleted. When the VDP appliance is configured properly, VMware documentation suggests this steady-state condition should occur around 80 % of the total storage allocated for the appliance.
IT administrators can monitor VDP storage use through the "Used Capacity" entry on the VDP reports tab. At 80% capacity utilization, VDP will warn administrators to a potential storage shortage. Unless there is a sudden influx of new VMs or additional data, administrators usually have plenty of opportunity to add storage or take other actions to mitigate storage use. These tactics usually involve removing unnecessary restore points, deleting unneeded jobs, refusing to backup new VMs, and reassessing retention policies to lower the overall data storage demands for VDP backups. Additional VDP appliances can also be deployed to provide more storage and improve overall backup performance or backup workload balancing.
At 95% capacity utilization, health check warnings are generated and the situation is typically a lot more serious. Existing backups are continued, but new backup tasks are prohibited until more capacity is available. At 100% capacity utilization, all backups are prohibited and VDP enters a read-only mode until the issue is rectified.
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