You are correct as far as it goes. What you are not taking into consideration is the overhead applied by the DASD controller to each physical block.
A complete calculation must take into consideration Record Zero + 255 Data Areas + 255 Count Areas + (Optionally) 255 Key Areas + all of the associated inter-block gaps. John P Baker Software Engineer -----Original Message----- From: Paul Gilmartin <[EMAIL PROTECTED]> Sent: Jul 20, 2005 4:25 PM To: [email protected] Subject: Re: capacity of largest drive In a recent note, John Baker said: > Date: Wed, 20 Jul 2005 15:09:13 -0400 > > You are correct, which brings back my original argument, which I must now > clarify. > > The maximum track size support by the ECKD architecture is 16,777,215. > My emulated calculator tells me 255 * 65535 is 16,711,425. Am I multiplying the wrong numbers? (But it's a nit.) > Within a track, the maximum data block size is 65,535. > > So, what is the maximum capacity of a logical device supported by the ECKD > archi > tecture? > > 65,535 cylinders / logical device > 65,535 tracks / cylinder > 17,777,215 bytes / track > Etc. I suspect that those who say increasing the 3390 values to anything larger would introduce compatibility problems are right. Isn't it time to stop taking small steps, which are incompatible anyway, and progress to FBA, preferably with 64-bit addressing? -- gil -- StorageTek INFORMATION made POWERFUL ---------------------------------------------------------------------- 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 ---------------------------------------------------------------------- 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
