NetVault Plug-in for VMware 11.1

Table 1. Data backed up and restored for different disk types
Disk Type	CBT-enabled Full Image Backups	Incremental/ Differential Image Backups	Restore of CBT-enabled Full Image Backups	Restore of Incremental/ Differential Image Backups
Thin (Required space supplied and zeroed out on demand.)	Only used disk sectors are backed up.	Only changed disk sectors are backed up.	Only used sectors are restored.	Only used disk sectors are restored. Each sector is restored only once.
Zeroed Thick (All space allocated at creation time, unused part zeroed out on first write.)	Only used disk sectors are backed up.	Only changed disk sectors are backed up.	Only used sectors are restored.	Only used disk sectors are restored. Each sector is restored only once.
Eager Zeroed Thick (All space allocated and zeroed out at creation time.)	All disk sectors are backed up.	Only changed disk sectors are backed up.	The entire disk is restored.	The entire disk is restored. Each sector is restored only once.
Virtual Compatibility RDM (Raw Device Mapping)	All disk sectors are backed up.	Only changed disk sectors are backed up.	The entire disk is restored.	The entire disk is restored. Each sector is restored only once.
Network File System (NFS)	All disk sectors are backed up.	Only changed disk sectors are backed up.	The entire disk is restored.	The entire disk is restored. Each sector is restored only once.

NOTE: Regardless of the disk provisioning type, image-level backups without CBT always back up the full disk size. Thus, backup of a 20GB thin-provisioned disk that only uses 2GB results in a 20GB backup.

When you restore a non-CBT backup, all blocks are restored and allocated. After a disk is restored from a non‑CBT backup, subsequent CBT-enabled Full Backups back up the entire disk.

RDM disks

The following table describes how the plug-in handles RDM (Raw Device Mapping) disks.

Table 2. Considerations for RDM disks

RDM compatibility mode

VADP-based backups and restores

Physical compatibility mode

The disk is not backed up. Warning messages are written to the NetVault Backup binary logs and job logs.

Virtual compatibility mode (Independent disks)

The disk is not backed up. Warning messages are written to the NetVault Backup binary logs and job logs.

Virtual compatibility mode

The disk is backed up, but the data can only be restored to a flat file. Warning messages about the change in type are written to the NetVault Backup binary logs and job logs.

Optionally, you can omit the RDM disks in virtual compatibility mode during a restore.

To omit the RDM disks in virtual compatibility mode

Open the vmware.cfg file in a text editor. You can find this file in <NetVault Backup home>\config on Windows and <NetVault Backup home>/config on Linux.

Edit the following entry and set the value to false.

[Custom:RestoreRDMDisks]

Value=False

Save the file.

Backup and recovery strategy

A well-designed backup strategy helps you to recover from the damages caused by failure and resume normal operations as quickly as possible. Before you start backing up your data, ensure that a good strategy is in place that safeguards your data against various failure modes, such as media failure, data corruption, user error, and complete loss of a data center.

Typically, your backup plan should define what backup methods are used, when and at what intervals the backups are performed, how the backups are stored, how long the backups are retained, and how the backup media are re-used.

The following are some example backup sequences to offer you guidelines:

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Full Backups only: You can choose to perform only Full Backups if the backup size is small, backup window is not an issue, or storage media is not a constraint. In such scenarios, you can schedule Full Backups every night or every N hours depending on the frequency of updates.

If a failure occurs, the plug-in is only required to restore a single saveset.

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Full and Incremental Backups: For quicker backups and minimum use of storage media, you can include Full and Incremental Backups in your strategy. For example, you can schedule Full Backups every Sunday and Incremental Backups every day or every N hours depending on the frequency of updates.

If a failure occurs, the plug-in is required to restore data from the recent Full Backup and each Incremental Backup in the backup sequence. The restore might take longer if several Incremental savesets have to be restored. For example, if the failure occurs on Saturday, the plug-in is required to restore the Full Backup taken on Sunday and Incremental Backups taken from Monday through Friday.

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Full and Differential Backups: For quicker restores and reduced media usage, you can include Full and Differential Backups in your strategy. For example, you can schedule Full Backups every Sunday and Differential Backups every day or every N hours depending on the frequency of updates.

If a failure occurs, the plug-in is required to restore data from the recent Full Backup and the last Differential Backup.