> -----Original Message----- > From: IBM Mainframe Discussion List > [mailto:[EMAIL PROTECTED] On Behalf Of McKown, John > Sent: Thursday, July 12, 2007 12:46 PM > To: [email protected] > Subject: Re: Track size and maximum single volume data set size > > > > -----Original Message----- > > From: IBM Mainframe Discussion List > > [mailto:[EMAIL PROTECTED] On Behalf Of J R > > Sent: Thursday, July 12, 2007 12:19 PM > > To: [email protected] > > Subject: Re: Track size and maximum single volume data set size > > > > > > >The tracks towards the center have fewer sectors than the > > tracks towards > > >the rim. > > > > Really? > > > >
Found another one which is more explicit: http://www.logicsmith.com/disklayout.html <quote> A current "zone-bit recording" or "variable data rate" disk drive has a variable number of data sectors per track. This is different from the old MFM and RLL drives that had all the user data recorded at a single data rate. Variable data rate recording was implemented to get more data on the disk. At the ID of a disk, the track length is roughly half what the length is at the OD, so if you record at a constant data rate, thereby getting a constant number of bits of data per revolution, you record at about twice the linear bit density at the ID as you do at the OD. If you can record twice as fast at the OD, you get the same bit density and twice as much data per revolution. </quote> ID = Inner Diameter OD = Outer Diameter -- John McKown Senior Systems Programmer HealthMarkets Keeping the Promise of Affordable Coverage Administrative Services Group Information Technology The information contained in this e-mail message may be privileged and/or confidential. It is for intended addressee(s) only. If you are not the intended recipient, you are hereby notified that any disclosure, reproduction, distribution or other use of this communication is strictly prohibited and could, in certain circumstances, be a criminal offense. If you have received this e-mail in error, please notify the sender by reply and delete this message without copying or disclosing it. ---------------------------------------------------------------------- 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
