ECKD architecture provides for a maximum track (head) number of 65535. It also provides for a maximum track capacity of 16777215 bytes.
All things considered, the maximum configuration for a single addressable device is 2**56 bytes - 2*32 bytes. The number of records per track is limited to 255 (excluding Record Zero). I just can't see a capacity limitation problem. John P Baker Software Engineer -----Original Message----- From: "McKown, John" <[EMAIL PROTECTED]> Sent: Jul 19, 2005 12:02 PM To: [email protected] Subject: Re: capacity of largest drive Notice how it seems to be the hardware designers that are forced to "fix" or work around limits in z/OS? Some limits I can understand due to backward compatability. But I don't know why the 3390 geometry is so "sacrosanct". A DASD address in the CCW is CCHH. Why do we seem to be stuck with an HH of 00..0F? We are wasting a nybble of addressing. After all, the 3350 and 3380 geometry was not "set in stone" back in MVS days. Of course, I am arguing from ignorance. I don't know what the code looks like. ---------------------------------------------------------------------- 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
