The following message is a courtesy copy of an article that has been posted to bit.listserv.ibm-main,alt.folklore.computers as well.
"Charlie Gibbs" <cgi...@kltpzyxm.invalid> writes: > On the other hand, if you wrote 200-byte physical records on a > CKD device, the overhead (inter-record gaps, count fields, etc.) > would exceed 50%. re: http://www.garlic.com/~lynn/2010d.html#0 PDS vs. PDSE http://www.garlic.com/~lynn/2010d.html#9 PDS vs. PDSE DASD capacity forumulae ... from my conversion of gcard ios3720 http://www.garlic.com/~lynn/gcard.html#26.3 DASD Capacity Formulae Device Cyls Tracks Track Bytes per record type /pack /cyl capacity without key with key 2305-1 48 8 14568 432+D 634+K+D 2305-2 96 8 14858 198+D 289+K+D 2314 200 20 7294 101+(D)534/512 146+(K+D)534/512 D (last on track) 45+K+D (last on track) 3330-1 404 19 13165 135+D 191+K+D 3330-11 808 19 13165 135+D 191+K+D 3340-35 348 12 8535 167+D 242+K+D 3340-70 696 12 8535 167+D 242+K+D 3350 555 30 19254 185+D 267+K+D 3375 959 12 36000 224+#(D+191) 224+#(K+191)+#(D+191) Device Cyls Tracks Track Bytes per record ... snip ... 3375 is a physical 3370 FBA (512byte blocks) with CKD emulated on top. All current CKD devices are actually physically fixed-block with CKD emulated on top (and things are quite a bit more complex) -- 42yrs virtualization experience (since Jan68), online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html