With parallel backup processing, you can use a single data mover node to back up multiple
virtual machines (VMs) at the same time to optimize your backup performance.
Before you begin
To back up VMware VMs, the following options are provided so you can optimize the
backups without adversely affecting the ESXi servers that are hosting the VMs. The options are
described in detail in the
options reference.
- vmmaxparallel
- The vmmaxparallel option is used to control the maximum number of VMs that can
be backed up at any one time. The optimal value for vmmaxparallel is not obvious;
it depends on the processing power of the vStorage server that the data mover node runs on, and the
performance of I/O between the data mover and the IBM Spectrum Protect server. For example, if you are moving data to the
server over a busy LAN, you might need to limit the number of VMs in each parallel backup operation.
Similarly, if the vStorage server processing capabilities are limited, for any reason, this is also
a reason to restrict the value for vmmaxparallel.
- vmmaxbackupsessions
- The vmmaxbackupsessions option is used to control the maximum number of data
movement sessions that can be included in the backup operation at any one time. Although this option
sets the maximum number of sessions that are allowed, the datamover determines the actual number of
sessions that are required based on the incoming workload and will use that number.
- The value of the vmmaxbackupsessions option must be equal to or greater than
the value of the vmmaxparallel option. If the value is less than the value of the
vmmaxparallel option, a message is returned and the value is changed to the same
value as vmmaxparallel option to ensure that there are as many sessions as there
are VMs.
- You might have to experiment with this setting to find the optimum value. Each dispatched VM is
guaranteed one session and then extra sessions are applied to the dispatched VMs. The number of
sessions will not exceed the value that is specified by the vmmaxbackupsessions
option.
- Other considerations for using this option include:
- If you are using the HotAdd data transport method, you will get better scale per session than if
you are using network block device (NBD) data transports. This difference allows a higher value for
the vmmaxbackupsessions option relative to a low value for the
vmmaxparallel option. If you are using NBD transport, the difference between the
vmmaxbackupsessions and vmmaxparallel options should be less
because of scaling issues caused by having multiple NBD sessions per VM.
- There is no performance benefit for setting the vmmaxbackupsessions option if
your storage system performance is slower than the available network speed between the data mover
and the server.
- vmlimitperhost
- The vmlimitperhost option is used to control how many VMs and virtual disks can
be backed up from an ESXi host at the same time.
- You might have to experiment with this setting to find the optimum value. On ESXi servers that
are heavily used, you might need to restrict the value for vmmlimitperhost so you
do not adversely affect the vSphere server performance. On servers that are not as heavily used, you
can include more VMs.
- If your are using the NBD data transport method, you might also exceed the network file copy
(NFC) protocol limit on the host if the value for vmlimitperhost is too high. In
this situation, a memory allocation error is returned as shown in the following
example:
ANS9365E VMware vStorage API error for virtual machine 'VM1'.
IBM Spectrum Protect function name : VixDiskLib_Read
IBM Spectrum Protect file : ..\..\common\vm\vmvddksdk.cpp (3062)
API return code : 2
API error message : Memory allocation failed. Out of memory.
- vmlimitperdatastore
- The vmlimitperdatastore is used to control how many VMs and virtual disks can
be backed up from a datastore at the same time. In a multiple datastore VMware environment, you can
use this option to reduce the burden that is placed on any one datastore during a parallel backup
operation.
Procedure
Complete these steps on the data mover system:
-
Start a command-line session:
Open a command prompt and change to the directory: cd
"C:\Program Files\IBM\SpectrumProtect\baclient". 
Open a terminal window and change to the directory: cd
/opt/tivoli/tsm/client/ba/bin.
-
Open the dsm.opt file with your preferred text editor.
-
Enter the option name and one or more blank spaces, followed by the option value.
For example:
vmmaxparallel 5
vmmaxbackupsessions 10
vmlimitperdatastore 5
vmlimitperhost 5
-
Issue the backup vm command.
For example:
dsmc backup vm vm1 -vmbackuptype=fullvm
Using the examples provided, the backup operations for the VM vm1 at the VM,
virtual disk, or subdisk level can include 5 virtual machines and 10 sessions. Backup operations are
limited to 5 VMs per datastore and 5 VMs per host.