Exchange Virtual Machine may freeze or dismount the Information Store when using vcbMounter
W2K3 Domain controller on VM
Can you rely on live backups of Exchange and SQL VMs?

Veeam Community Forums - How to improve backup speed: VCB performance in SAN mode geeft aan dat in sommige gevallen de snelheid van VCB backup verhoogt kan worden door HBA drivers te updaten en/of multipathing uit te zetten op de VCB-proxy server.

Considerations When Creating Snapshots
When creating snapshots, keep in mind the following:

• Taking a snapshot of a virtual machine freezes it for a very short period of time, usually considerably less than a second.
  
• Creating a memory snapshot through the UI can leave a virtual machine frozen for a couple of seconds. This might affect some very time-sensitive applications, such as DBHammer.
  
• Creating quiesced snapshots using the SYNC driver requires waiting for I/O to drain in the guest operating system. This might affect some very time-sensitive applications, such as DBHammer.
  
• If you choose not to install the SYNC driver when installing VMware Tools, you can avoid the delay caused by the I/O draining. However, it results in snapshots being only crash-consistent, unless you provide custom quiescing through pre/and post-scripts in the guest.
  

Bron:VMware Virtual Machine Snapshot Technology