On Wed, 2 Jul 2008 16:29:50 -0400, Thompson, Steve wrote: > >Is it CKD vs. FBA? Or is this caused by it being cheaper to emulate CKD >on RAID? And then, to continue with 3390 based geometry because it is >cheaper to do that than to put out a new DASD device?
What does you mean, Steve? All of the disk drives that everyone makes today are FBA. Do you think it would be more expensive for a DASD subsystem to emulate FBA using FBA disks than it is to emulate CKD using FBA disks? In fact, I'm pretty sure that every DASD manufacturer today will let you define the logical devices as FBA. > >IF FBA were such a wonderful thing, why hasn't some company that makes >disk units (or did) put out FBA for "MVS" with their own device >handler/driver? What incentive does Seagate or EMC (for example) have to write a lot of code for MVS to support FBA devices? How would they support using all the undocumented and unsupported interfaces that they'd have to use to do it? How many customers would want to modify MVS with that level of changes from a third party vendor? How much existing code would break? Example: PDS uses TTR in the directory to point to the member. Lots of code depends on TTR. -- Tom Marchant ---------------------------------------------------------------------- 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
