One of the best features of most modern virtual backup products, is that they support the vStorage APIs for Data Protection (VADP), including change block tracking (CBT) and hot-add.
More here on VADP: kb.vmware.com/kb/1021175
To take advantage of the vSphere hot-add ability, the backup server itself must be a VM with access to the same storage and datastores of the VM’s it is backing up.
Veeam calls this virtual appliance mode and similar techniques are used by other products from PHD Virtual and VMware (VDR). Ultimately it means backups are very fast, LAN free and are “localised” to the backup server.
Veeam fully supports this configuration, but depending on your how many VM’s you are backing up, the capacity and the backup window – it does have some small challenges.
Firstly, we all know the storage Achilles heal of vSphere 4 is its 2TB (minus 512 bytes) limit on VMDK’s or RAW disks passed through to the VM.
If you plan to keep a month of compressed and de-duped backups of 100 Server VM’s, 2TB may well be a drop in the ocean of data.
In my environment, backing up 80+ VM’s and keeping versions for 30 days, this results in around 12TB of data – this includes SQL servers, Exchange, File and Content Management servers – and the usual suspects in a corporate Windows environment.
So, do we present multiple 2TB VMDK’s or RAW disks to the Veeam Backup VM and then spread jobs across the drives? Perhaps aggregate and stripe them using Windows disk manager? Both of these options will work, but I preferred a simpler and cleaner single disk/volume solution.
Using the Windows iSCSI initiator inside the VM allows me to present huge volumes directly to the 64-bit Windows server VM from the iSCSI SAN – avoiding those nasty 32-bit SCSI2 limits of vSphere currently.
So onto some technical aspects on how I have this configured.
The Windows VM itself, is Server 2008 R2.
It is configured with 6 vCPU and 8GB ofRAM, as i said previously, depending on your workload, this may be overkill, or perhaps not enough.
I find that two running jobs can saturate a 6 vCPU VM running on top of a Westmere based blade server.
Presented to this is a 20TB Volume from an HP P4000 G2 SAN (iSCSI)
The VM has two dedicated vNics (VMXNET3) for iSCSI, both are separated onto different dedicated virtual machine port groups on the ESX host side, which are on the iSCSI VLAN. (See two images below)
Each of the port groups have been configured with manual fail-over order to set the preferred active physical adapter. iSCSI Network 1 using vmnic2 and iSCSI Network 2 using vmnic3 (see two images below)
This means that the two virtual nics in the VM traverse separate physical nics coming out of the ESX hosts.
Then using the iSCSI initiator software inside Windows 2008 R2 and installing the HP DSM driver for iSCSI Multipathing to the P4000 (other iSCSI vendors should also have MPIO packages for Windows)
Docs on how to configure under this in Windows are available from HP:
This allows Windows to use both nics and perform round-robin load balancing to the volume on the iSCSI storage array. In the two images below, you can see the iSCSI target tab and both paths to the volume.
The end result is a gigantic multi-pathed multi terabyte volume available for Veeam Backup 5 to drop its backups onto and with all the the advantages of using your virtual infrastructure (HA/DRS etc.)
More info on Veeam Backup and Replication at their site: