We are using a W2K8R2 server and 2 SNs along with 2 DD880s (no VTLs). We create 
about 4k save sets/day and have about 5 failed ones.

Most of them are due to
  - Non-communicated client reboots/shutdown
  - Network related issues (name resolution issues)
  - Older client hard/software which is not updated because these will be 
migrated in the future.

What i urge you is to avoid a VTL. 
Why do you want to use it and add an unnecessary 'layer'? - Just to maintain 
the legacy tape backup environment/feeling?
Worst case it is just another element which CAN only lower the reliability of 
the whole backup environment. Eliminate what you don't need!

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