In a message dated 7/20/2005 4:32:17 P.M. Central Daylight Time, [EMAIL PROTECTED] writes:
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. New controller microcode would be needed to allow 255 records, each of which was 65535 bytes long with a possibly 255-byte-long key, to occupy the same one virtual track. Given the need for new microcode, why must we continue the legacy of overhead for R0, count areas, and gaps? Let the new virtual track size be as large as it needs to be. So maybe it exceeds 16MiB by a few thousand bytes and thus needs more than 24 bits. Who cares? It's all virtual and being mapped onto real disks through complex mapping algorithms. 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
In a message dated 7/20/2005 4:32:17 P.M. Central Daylight Time, [EMAIL PROTECTED] writes: 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. New controller microcode would be needed to allow 255 records, each of which was 65535 bytes long with a possibly 255-byte-long key, to occupy the same one virtual track. Given the need for new microcode, why must we continue the legacy of overhead for R0, count areas, and gaps? Let the new virtual track size be as large as it needs to be. So maybe it exceeds 16MiB by a few thousand bytes and thus needs more than 24 bits. Who cares? It's all virtual and being mapped onto real disks through complex mapping algorithms. 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
