Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site brl-tgr.ARPA Path: utzoo!watmath!clyde!bonnie!akgua!gatech!seismo!brl-tgr!tgr!trwspf!jabba!expert@lbl-csam.arpa From: expert@lbl-csam.arpa Newsgroups: net.unix-wizards Subject: hp.c (4.1bsd) Message-ID: <46@brl-tgr.ARPA> Date: Mon, 25-Nov-85 12:32:28 EST Article-I.D.: brl-tgr.46 Posted: Mon Nov 25 12:32:28 1985 Date-Received: Wed, 27-Nov-85 05:23:58 EST Sender: news@brl-tgr.ARPA Lines: 39 Can somebody help me, please? We run a VAX 750 with 4.1bsd and SI disk drives. We are planning on installing a 300Mbyte (pseudo-RM05) drive and I've been looking through hp.c. There seem to be some magic numbers in the "size" structure (partitioning info.) for the drives, which I don't understand. "Size" has two parts: 'daddr_t nblocks' (which turns out to be type 'int') and 'int cyloff'. It appears that 'cyloff' is the cyl. offset to the start of the partition. But where do the numbers for 'nblocks' come from? There are 8 partitions set up in my hp.c: nblocks cyloff comment ------- ------ ------- 15884 0 "A" = cyl 0 thru 26 33440 27 "B" = cyl 27 thru 81 500384 0 "C" = cyl 0 thru 822 15884 562 "D" = cyl 562 thru 588 55936 589 "E" = cyl 589 thru 680 86240 681 "F" = cyl 681 thru 822 158592 562 "G" = cyl 562 thru 822 291346 82 "H" = cyl 82 thru 561 According to my calculations, this means that the number of 'nblocks' per cly. is anywhwere from 588.3 to 608.0. (I can also see that the final partition scheme I use will make a big difference in how much space I can use: Using "A"+"B"+"H"+"D"+"E"+"F" gets 498730 blocks Using "A"+"B"+"H"+"G" gets 499262 blocks Using "C" gets 500384 blocks; I can believe this, due to wasted space in partitioning.) Further, it appears that the numbers to use in /etc/mkfs are 1/2 of the 'nblocks' number (for "size") along with the standard '3 304' (for "m" and "n"). Is this correct? Help, please. Richard Collins (trwspf!expert@lbl-csam)