Whist the terminology in documents may have changed the support status has not so I am not 100% sure where the belief that we "no longer officially supports tape drive connectivity to a backup server running on VMware" comes from (unless you were referring to some potentially incorrect documentation that existed in the ESX 3.5 timescale - see below)
Some history:
in ESX 3.5 documents, VMware originally stated that Tape drive passthrough was supported as long as certain Adaptec SCSI cards were used - our documentation at the time assumed supported because of VMware's statement, however even back then we had not officially tested such a configuration and our documentation therefore did have a problem. Note: The VMware documentation was only for passthrough, no capability to manage a tape device was included as part of the ESX host operating system (although there was no clear documentation making this point.)
in ESX 4.0 documents from VMware, the text covering tape drive passthrough was changed to indicate that whether or not it was supported was now down to the backup software vendor (in other words Symantec/Veritas) to confirm and document. Not long after this, Symantec rewrote our documentation to indicate that such a configuration had not been officially tested by us and we defined it as an Alternative Configuration that did not have official support.
Since this rewrite of Symantec documentation (during the ESX 4.0 timescale) we still do not certify tape drive passthrough and our support status has not changed (although it looks like VMware may have added a statement into their document, at some point, that states that they do not provide any tape management on the host. Our documentation has periodically been edited to add in updated versions (and has now moved to Veritas branded) but such a configuration has, to all intents and purposes, remained as not officially supported and defined as an Alternative Configuration.
In terms of what customers have been doing (with ESX 4.x forwards), we do know that some have configured tape passthrough (including CraigV above). Whilst we do not know if any have been reliably using such a configuration (as no one tells us when things work) we have seen feedback in both these forums and the odd case that reached Tech Support that indicates that unpredictable device connectivity issues can occur with symptoms such as failures during tape read or write operations, inability to move tapes from slots to drives and hardware (drives or libraries) going offline. Some customers found a systems restart resolves the issue temporarily but then it will come back, meaning you cannot rely on the connectivity and as far as we are aware any customers with problems are no longer using such a configuration.
