VSSI's VTAPE is a software simulation of tape I/O that creates virtual tapes on disk. It was first created to answer the needs of ACP, later to be known as TPF, development. TPF is very tape hungry, both in numbers of drives needed and tapes created. The tapes in a development and test environment are typically small, so they can easily be accommodated in a VTAPE Library that is completely dasd resident. Since no real tapes are used, you define a virtual drive rather than attach a real one. In addition to creating VTAPEs, it is possible to mount infinitely long write only tapes, otherwise known as Dummy tapes, if you only need to simulate the I/O but do not need to see the data.
There are no backing tapes as there are in the IBM VTS or similar systems. In those systems, the virtual tapes age off of DASD onto real tapes and are recalled if mounted by a user. Size can also dictate whether a real tape is used. In the VTAPE world, there is no accompanying silo with its real tapes, tape drives and robots. There would be no such thing as a big TPF development shop had it not been for VTAPE because the expense of the tape drives, tape libraries, people to run them and facilities to house them would have been prohibitive. Currently, our VTAPE Library consists of 26 3390-03s. We typically have 16 drives defined for each of the TPF testers. Our average number of concurrent TPF test virtual machines is over 100, so it is normal for there to be over 1600 defined virtual tape drives. We could not do anything like that if we needed to attach real tape drives and mount real tapes. VSSI's VTAPE is a great product for what it does. That said, it probably is not a replacement for real drives and tapes, especially for a moderately large shop. Trying to create the tapes needed for a full system backup, for example, on VTAPE just simply would not work. Also, if you need to exchange tapes with most other systems, it would not work. I said "most other systems" because it is possible for any system that shares the DASD where the VTAPE Library resides to share the library if that system also has VTAPE installed. In that case, exchanging tapes is a snap. As Christy Brogan said, installation is a breeze. VSSI provides a set of utilities for installing it and the instructions are quite clear. Also, their support is the standard that I use to measure other Regards, Richard Schuh > -----Original Message----- > From: The IBM z/VM Operating System > [mailto:[EMAIL PROTECTED] On Behalf Of Shiminsky, Gary > Sent: Wednesday, September 03, 2008 9:53 AM > To: [email protected] > Subject: VTAPE from Virtual Software Systems > > Hi, > > We are looking for a virtual tape system as part of a project > to replace our ageing tape drives. > > Does anybody have any experience with VTAPE from Virtual > Software Systems that they would like to share? > > Gary > > Gary L. Shiminsky > > VM/VSE Senior Systems Programmer > Office of Information Technology > State of New Hampshire > 27 Hazen Drive > Concord, NH 03301 > 603-271-1509 Fax 603-271-1516 >
