You can use several backup techniques to back up virtual
machines.
Use the following information to determine which virtual
machine backup technique to use that best meets your needs and environment.
Windows Hyper-V backup
The client can back up virtual
machines that are hosted by a Hyper-V server on Windows systems.
- How it works
- Full virtual machine backup processing backs up and restores snapshots
of Hyper-V virtual machines by using the Microsoft Volume Shadow Copy Services (VSS)
interface. You can restore a virtual machine by using the files that
are created by VSS.
- Advantages
- Hyper-V backup processing has the following advantages:
- This method can back up data without stopping the virtual machine
or stopping any running applications within the virtual machine when
the guest virtual machine is running a VSS-enabled Windows operating system.
- This method can restore either individual virtual machines or
a group of virtual machines that run on a Hyper-V server for disaster
recovery purposes.
- This method adds backup and restore functions for guest operating
systems without the need for you to install a Tivoli® Storage
Manager client on
the guest virtual machine.
- This method can be used for both disaster recovery and long-term
data backup support.
- Disadvantages
- Hyper-V backup processing has the following disadvantages:
- Backups are not granular.
- You cannot run individual file restore operations from a full
virtual machine backup.
VMware full virtual machine backup
Full virtual machine backup processing backs up a virtual machine
from a VMware ESX or ESXi-based host.
- How it works
- Full virtual machine backup processing stores a backup copy of
all virtual disk images and configuration information for a virtual
machine.
- Advantages
- With full virtual machine backup processing, you get faster data
movement than a file-level backup.
- Disadvantages
- Full virtual machine backup processing has the following disadvantages:
- Backups are not granular.
- Full virtual machine backup operations enable a complete restore
of a virtual machine, but they take more time and more server space
than a file-level or incremental backup.
- You can restore individual files from a full virtual machine backup
only with IBM® Tivoli Storage Manager for Virtual
Environments.
- This method is only available on Linux and Windows clients.
VMware incremental backup
You can run an incremental backup of a virtual
machine from a VMware ESX or ESXi-based host. Incremental backup processing
requires a Tivoli Storage
Manager for Virtual Environments license.
- How it works
- An incremental backup of a virtual machine backs up all changes
that occurred since the previous backup of the virtual machine, whether
the backup was a full backup, or another incremental backup.
- Advantages
- Incremental backup processing backs up changes to virtual machines
between full virtual machine backups.
- Disadvantages
- Incremental backup processing of a virtual machine has the following
disadvantages:
- The size of incremental backups can increase if you do not run
a full backup regularly.
- It is inefficient to restore data from incremental backups because
the process must automatically complete the following tasks:
- Restore the most recent full backup.
- Restore each incremental backup up to the specified
recovery point.
- This method is available only on Linux and Windows clients.
VMware incremental-forever-full virtual
machine backup
Incremental-forever-full virtual machine
backup processing backs up all the used blocks on a VMware virtual
machine's disks. To run this type of backup, you must have a license
to use Tivoli Storage
Manager for Virtual Environments V6.4 or later.
- How it works
- The following processes occur during incremental-forever-full
virtual machine backup processing:
- A full virtual machine backup is required only one time.
- Data from incremental backups is combined with data from the full
backup to create a synthetic full backup image. This type of full
backup is called synthetic because it is created from the data that
is stored on the server and not from reading the used blocks on the
production disks.
- Subsequent incremental-forever-full virtual machine backup operations
read all used blocks and copy those blocks to the server.
- Each incremental-forever-full virtual machine backup operation
reads and copies all of the used blocks, whether the blocks are changed
or not since the previous backup.
- Advantages
- Incremental-forever-full virtual machine backup processing has
the following advantages:
- Periodic full backups are no longer necessary.
- During a restore operation, you can specify options for a point
in time and date to recover data. The data is restored from the original
full backup and all of the changed blocks that are associated with
the data.
- Disadvantages
- Incremental-forever-full virtual machine backup processing has
the following disadvantages:
- If one or more of the progressive incremental backups is corrupted
on the server, you might not be able to fully recover a virtual machine.
To ensure that you can fully recover a virtual machine, periodically
run a full virtual machine backup.
- This method is available only on Linux and Windows clients.
VMware incremental-forever-incremental
backup
Incremental-forever-incremental backup processing
backs up only the disk blocks that have changed since the last backup.
To run this type of backup, you must have a license to use Tivoli Storage
Manager for Virtual Environments V6.4 or
later.
- How it works
- The following processes occur during incremental-forever-incremental
backup processing of a VMware virtual machine:
- A full virtual machine backup is required only one time.
- A full virtual machine backup operation copies all of the used
disk blocks that are owned by a virtual machine to the Tivoli Storage
Manager server.
- After the initial full backup, all subsequent backup operations
of the virtual machine are incremental-forever-incremental backups.
- This method copies only the blocks that changed since the previous
backup, regardless of the type of the previous backup.
- The server uses a grouping technology that associates the changed
blocks from the most recent backup with data that is already stored
on the server from previous backups.
- A new full backup is then effectively created each time changed
blocks are copied to the server by an incremental-forever-incremental
backup.
- Advantages
- Incremental-forever-incremental backup processing has the following
advantages:
- Periodic full virtual machine backups are no longer necessary.
- This method reduces the amount of data that goes across the network.
- This method reduces data growth because all incremental backups
contain only the blocks that changed since the previous backup.
- No comparison with the backup target is required since only changed
blocks are identified.
- Impact to the client system is minimized.
- The length of the backup window is reduced.
- Data restore operations are simplified.
- This method optimizes data restore operations.
- Disadvantages
- Incremental-forever-incremental backup processing has the following
disadvantages:
- If one or more of the progressive incremental backups is corrupted
on the server, you might not be able to fully recover a virtual machine.
To ensure that you can fully recover a virtual machine, periodically
run a full virtual machine backup.
- It is available only on Linux and Windows clients.
VMware file-level backup on Windows
On Windows systems, you can use the backup-archive
client to create file-level backups of VMware virtual machines.
- How it works
- The following processes occur during file-level backup processing
of a virtual machine:
- A VMware snapshot is taken of the virtual machine to be backed
up.
- The file systems of the virtual machine are remotely mapped to
the vStorage backup server.
- A file-level progressive incremental backup is run for all of
the file systems.
- The data is stored under the node name that matches the host name
of the virtual machine.
- The data for each virtual machine is stored in the node that is
associated with the virtual machine.
- The file system mappings are removed and the snapshot is removed.
- When to use
- Use file-level virtual machine backup processing if you want the
ability to restore individual files from a virtual machine but you
do not have a license for Tivoli Storage
Manager for Virtual Environments.
- Advantages
- File-level virtual machine backup processing has the following
advantages:
- You can use include and exclude rules to identify the files to
back up.
- Files are backed up as individual files rather than as an image
backup.
- Disadvantages
- File-level restores must be made from a backup-archive client
that is installed directly on a virtual machine guest.
Parallel backups of VMware virtual
machines
You can improve performance of virtual machine
backups by running parallel backups of multiple virtual machines by
using a single instance of the backup-archive client. This feature
is only available in the Tivoli Storage
Manager V6.4 or
later client.
- How it works
- The following processes occur during parallel backup processing
of virtual machines:
- A single Tivoli Storage
Manager data mover node can be used to concurrently back up multiple
virtual machines.
- When the backups are initiated, the client establishes parallel
sessions to copy the data to the Tivoli Storage
Manager server.
- Advantages
- Parallel virtual machine backup processing has the following advantages:
- The backup window is reduced.
- You can optimize the backups so that they do not adversely affect
the ESX servers that are hosting the virtual machines.
- Disadvantages
- You must optimize the parallel backups. The number of virtual
machines that you can back up in parallel depends on the following
factors:
- The processing power of the vStorage server that the Tivoli Storage
Manager data mover
node runs on.
- The performance of I/O between the client and the Tivoli Storage
Manager server.