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VMware Backup Set

AhsayOBM allows you to back up individual Guest virtual machines (VMs) on your VMware hosts with our VMware Backup Set. VMware Guest VM backup module of AhsayOBM provides you with a set of tools to perform hot backup of your running VMs in VMware environment.

When you need to restore a VM, besides restoring the whole VM image, you can also utilize the built-in Run Direct feature to spin-up the VM in minutes without the need to restore the whole VM first. Moreover, our Granular Restore feature allows you to mount the virtual disks in a backed up VM and restore individual files within the VM without the need to spin-up the VM first.

System Architecture

Below is the system architecture diagram illustrating the major elements involved in the backup process among the VMware server, AhsayOBM and AhsayCBS. In this user guide, we will focus on the software installation, as well as the end-to-end backup and restore process using the AhsayOBM as a client backup software.

Instant VM Restore with Run Direct

What is Run Direct?

Run Direct is a feature that helps reduce disruption and downtime of your production VMs. Unlike normal VM restore procedure where a VM is extracted from backup files and copied to the production storage, which can take hours to complete. Restore with Run Direct can instantly power up a VM by running it directly from the backup files in the backup destination and the VM can be put into production.

How does Run Direct work?

When a Run Direct restore is performed, the backup destination is mounted as an NFS datastore from the VMware host, where the VM is run directly from the backup files.

The backup destination can either be the AhsayCBS server or a local drive that can connect with AhsayOBM. Initiating a Run Direct from the AhsayCBS (also known as agentless restore) will trigger a connection directly with the VMWare host (ESXi server and the direction shown in orange indicator below), while initiating the same action on the AhsayOBM requires the connection to route through the OBM (shown in green indication below).

The restored virtual machine, at this stage (e.g. before the restore is finalized) is in a read-only state to preserve its integrity. All changes made to the virtual disks (e.g. operation within the guest virtual machine) are stored separately in transaction logs stored on the NFS datastore or the original datastore, depending on the setting selected. These changes are discarded when Run Direct is stopped, where the restored VM will be removed and all changes will be discarded, or the changes will be consolidated with the original virtual machine data when the restore is finalized.

The restored virtual machine, at this stage (e.g. before the restore is finalized) is in a read-only state to preserve its integrity. All changes made to the virtual disks (e.g. operation within the guest virtual machine) are stored separately in transaction logs stored on the NFS datastore or the original datastore, depending on the setting selected. These changes are discarded when Run Direct is stopped, where the restored VM will be removed and all changes will be discarded, or the changes will be consolidated with the original virtual machine data when the restore is finalized.

Settings Differences between Run Direct and Non-Run Direct Backup Set on VMware

Run Direct Backup Set Non-Run Direct Backup Set
Encryption No Yes
Compression No Yes
VDDK (CBT) Yes Yes
AhsayCBS Yes Yes
Local Destination Yes Yes
Cloud Destination No Yes

Finalizing a VM Recovery (Migrating VM to permanent location)

To finalize recovery of a VM, you will still need to migrate it to a permanent location on the VMware host. The following steps are taken when you finalize a Run Direct restore:

1). VMware Snapshot

A VMware snapshot is created for the VM

2). Copying Files

Backup files from the NFS datastore are copied to the production datastore on the VMware host.

3). Copying Changes

Changes made to the VM after the snapshot creation are moved to the new location.

4). Data Consolidation

The VM is temporarily suspended to consolidate the changes made after the snapshot creation.

5). Resume VM

After all changes are consolidated, the VM is resumed.

6). Dismount NFS datastore

The NFS datastore is dismounted.

NOTE
For vCenter VM backup set, provided that the vMotion feature of the vCenter set is working properly, the VM will not be suspended during the data consolidation.

Backup Mode

There are two backup modes available for VM backup:

VDDK Backup Mode

For VM on VMware host on Enterprise Standard, Enterprise and Enterprise Plus Edition, backup is performed in VDDK mode. Backup in VDDK mode produces a backup chain that consists of a full VDDK file and a set of VDDK incremental files.

  • During the first backup, full files (*.F.vddk) are created in the backup destination.
  • During subsequent backup, Changed Block Tracking (CBT) - a VMware native feature is employed, to identify disk sectors altered since the last backup. Altered blocks are saved as incremental VDDK file (*.I.vddk) in the backup chain.

During a subsequent backup in VDDK mode, AhsayOBM queries CBT through VADP (vSphere APIs for Data Protection) to request for transmission of all altered blocks since the last backup. As there is no need to stream the VM files to the Backup Client Computer for delta generation, backup in VDDK mode will greatly enhance the speed of subsequent backup.

Pro Faster backup speed for subsequent backups compared to non-VDDK backup, as a result of backing up only the used size of your VM instead of the entire machine to enhance backup efficiency. This also helps with minimizing the storage size requirement and saving storage cost.
Con Require paid license, i.e. VMware Essentials License for usage of vSphere API.

Non-VDDK Backup Mode

For VM on VMware host on Enterprise Standard, Enterprise and Enterprise Plus Edition, backup is performed in VDDK mode. Backup in VDDK mode produces a backup chain that consists of a full VDDK file and a set of VDDK incremental files.

  • During the first backup, full files (e.g. virtual disk file (*.vmdk)) are created in the backup destination.
  • During subsequent backup, In-file delta - an AhsayOBM feature is employed, to track only data blocks that have change since the last backup. All changed data blocks are saved as incremental / differential delta files in the backup chain.

During a subsequent backup in non-VDDK mode, VM files are streamed to the Backup Client Computer, for delta generation:

Pro Free version of ESXi is supported.
Con Slower backup speed for subsequent backup compared to VDDK backup, as a result of having the entire VM backed up every time regardless of the actual used size.

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public/vmware.1565938266.txt.gz · Last modified: 2019/08/16 14:51 by ronnie.chan

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