Maybe phrasing your question differently would be what are the advantages and disadvantages of physical tape data versus a tape-on- disk approach?
TMM is a methodology, which temporarily stages tape data on Level 0 disk and then the TMM pool is managed by DFSMShsm or equivalent to consolidate this data on physical tape. The resulting physical tapes will then have data sets with varying expiration criteria and so will require recycling periodically and from a DR/BC viewpoint will require duplicating, as and if required. IBM Virtual Tape for Mainframe (VTFM) essentially is a virtual tape solution, emulating 3480/3490/3590 drives and allocating tape data to physical z/OS DASD. Of course, there are many other z/OS virtual tape solutions, with a tape-on-disk type concept, CA VTape being a software example, requiring physical tapes for data destaging, with Bus-Tech MDL/EMC DLm, Luminex, Universal Software, Intercom being appliance solutions that allocate tape data to FC/NAS disk arrays, without subsequent data destaging to physical tape, and of course IBM TS7700 (VTS), Oracle/StorageTek VSM and FSC CentricStor being solutions that combine a disk cache and physical tape. So thinking of Sherlock Holmes when you have eliminated the impossible, whatever remains, however improbable, must be the truth, maybe you could review all of the tape-on-disk options, which include TMM? Some advantages of those solutions, and so for the avoidance of doubt, Bus-Tech MDL/EMC DLm, Luminex, Universal Software, Intercom, et al, is that the resulting ML2 type data, can be easily recycled, as the tape data is on cost-efficient FC/SAN disk, and thus easier data replication for BC/DR is also possible. Equally, ML1 type operations could also be eliminated, with all of the resource considerations (E.g. CPU, z/OS class DASD) associated with that process. Thus for the avoidance of doubt, avoid ML1 disk costs and zSeries CPU cycles, by eliminating ML1 from the storage hierarchy and go direct to ML2, where compression is performed outboard of the Mainframe and tape data allocated on less expensive FC/IP disk arrays, potentially with the benefits of deduplication. All that said, maybe even TMM can co-exist with such a tape-on-disk methodology. As with any IT solution, identify your business requirements first and then research what products best fit your business requirements with the best ROI and TCO attributes. So maybe VTFM isnt for you and maybe TMM can be approached from a different viewpoint for you by utilizing other virtual tape technologies. On Mon, 22 Nov 2010 11:30:08 -0500, techie well wisher <[email protected]> wrote: >IBM has VTFM (which is diligent/copycross, etc). Why do we need this product >or use this product while we can directly intercept and direct >allocations to a particular storage group (such TMMGROUP) with disk volumes, >let's say a dedicated set aside pool from a storage device? With extended >dataclas attribute, the datasets in this group could be really huge (several >gigabytes). To me, this product adds unnecessary complexity. With this, we >don't need PAT (parallel tape access), because all the datasets in this >group are disk datasets, accessible by multiple address spaces/jobs. Pleaset >let me know your thoughts or am I missing something here? > >TW ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
