In a message dated 7/19/2005 9:15:08 A.M. Central Daylight Time, [EMAIL PROTECTED] writes:
There is nothing in the UCB or DCE to distinguish a 'model-27' from a model-9. The only indication is capacity - and in the days of short-genning logical volumes that is a very unreliable way of determining a device model type. The DCE (UCB DASD Class Extension) has two different halfword fields indicating capacity. It would appear that the next model larger in capacity than the model 54 with 65520 cylinders will push the envelope off its edge. One reason why the capacity keeps going up is so IBM can postpone giving us more than 65536 devices on one LPAR. Something's gotta give pretty soon. Or maybe the DCE can be expanded by adding a prefix. :-) I haven't studied a DCE yet for a model 27 or model 54, but I would expect the MDR and OBR device type code fields (DCEMDRDT and DCEOBRDT) or the real device ID field (DCERDVID) would contain unique values that would tell which fat model type the device is. Why would one need to know if a device is a model 27 or 54 as opposed to knowing its capacity (unless one were writing highly device type-specific code, as in error recovery)? Bill Fairchild ---------------------------------------------------------------------- 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
