You can use Tivoli® Storage FlashCopy® Manager for VMware to
back up virtual machines that contain raw
device-mapping disks.
However, only standard virtual disks can be restored or attached.
Raw device mapping allows a special mapping file in a Virtual Machine
File System (VMFS) volume to act as a proxy for a logical unit number
(LUN) on a storage device. The mapping file, not the LUN, is referenced
in the virtual machine configuration. When a LUN is accessed, the
mapping file is read to obtain the reference to the LUN. Using the
reference to the LUN, read and write operations can access the LUN
directly rather than accessing it through the mapping file.
During the initial configuration, you can decide on the default
backup mode. This mode determines how virtual machines selected for
backup are processed before the actual hardware snapshot of the
datacenter occurs.
However, when you create a new backup task, you can override the type
of backup mode to use. Depending on the defined backup mode, the following
actions are taken when you backup a virtual machine that contains
raw
device-mapping disks:
- VM Backup mode: SNAPSHOT_INCL_MEM or SNAPSHOT_EXCL_MEM
- For both of these backup modes, the mode is changed to ASIS. This
change is required because it is not possible to restore the snapshot
because the raw
device-mapping disks are not present on the restored virtual machine.
In this case, a VMware virtual machine snapshot is not performed before
the actual hardware snapshot. The snapshot that is created through
this process is crash consistent only. A warning message is issued
when this backup mode change occurs.
- VM Backup mode: SUSPEND
- This mode is not changed regardless of whether the virtual machine
has raw
device-mapping disks or not. In this case, a VMware virtual machine
snapshot is not created before the actual hardware snapshot.
Note: The backup mode change occurs for a Tivoli Storage FlashCopy Manager for VMware backup
only. The mode is not changed when you do a snapshot backup with a
subsequent offload to Tivoli Storage
Manager. The
restore process from Tivoli Storage
Manager server,
maintains a file system level consistency, for backup modes SNAPSHOT_INCL_MEM and SNAPSHOT_EXCL_MEM.
When
Tivoli Storage FlashCopy Manager for VMware is
integrated with
Tivoli Storage
Manager for Virtual Environments,
you still can achieve a file system level consistency backup by using
one of the following methods:
- Direct backup to Tivoli Storage
Manager for Virtual Environments.
- Create a backup task that offloads the Tivoli Storage FlashCopy Manager for VMware snapshot
to Tivoli Storage
Manager.
The backup mode SNAPSHOT_INCL_MEM or SNAPSHOT_EXCL_MEM is
not altered in this case, so that a restore from Tivoli Storage
Manager, maintains
file system level consistency.
Other options to consider when you backup a virtual machine that
contains one or more
raw
device-mapping disks:
- Metadata for the raw
device-mapping disks
is included in the backup but this metadata cannot be restored.
- Tivoli Storage
Manager for Virtual Environments can
offload a virtual machine from a Tivoli Storage FlashCopy Manager for VMware backup
to Tivoli Storage
Manager.
The raw
device-mapping disks are not included in the offload. This type
of offload occurs when Tivoli Storage FlashCopy Manager for VMware is
integrated with Tivoli Storage
Manager for Virtual Environments.
Ensure that the parameters in the VMCLI section of the profile file
that relate to Tivoli Storage
Manager for Virtual Environments are
configured.
- If you use the Data Protection for VMware command-line interface or Tivoli Storage FlashCopy Manager for VMware
GUI to
back up virtual machines, a warning is issued listing all the raw
device-mapping disks
that are not included in the backup.
- Tivoli Storage FlashCopy Manager for VMware removes
the raw
device-mapping disks from the virtual machine configuration after
a restore process.
The following restrictions apply when you restore or attach virtual
machines that include
raw
device-mapping disks:
- You cannot restore raw
device-mapping disks
because the content of the raw
device-mapping volume
is not part of the backup. The VMware snapshots that are created by
the user before the backup are no longer available.
- You cannot attach raw
device-mapping disks
from a virtual machine backup. In the Tivoli Storage FlashCopy Manager for VMware
GUI,
the raw
device-mapping disks are not displayed.
- You cannot use the Data Protection for VMware command-line interface to
attach disks by specifying the disk-key of a raw
device-mapping disk.