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!linus!philabs!cmcl2!seismo!brl-tgr!tgr!mangler@cit-vax From: mangler@cit-vax (System Mangler) Newsgroups: net.unix-wizards Subject: Re: Fast Filesystem defaults Message-ID: <621@brl-tgr.ARPA> Date: Mon, 12-Aug-85 07:44:11 EDT Article-I.D.: brl-tgr.621 Posted: Mon Aug 12 07:44:11 1985 Date-Received: Wed, 14-Aug-85 03:27:02 EDT Sender: news@brl-tgr.ARPA Lines: 31 > If you have one inode per 2K of data space, then it doesn't matter > how many blocks/cyl-group; more blocks just means more inodes. So > how does having rp07s make any difference? Mkfs cannot allocate more than MAXIPG (=2048) inodes per cylinder group. With 16 cylinders per group, this limit comes into play on any drive with more than 512 sectors per cylinder. RM05 19 x 32 = 608 effective -i value = 2432 RA81 14 x 51 = 714 effective -i value = 2856 Eagle 20 x 48 = 960 effective -i value = 3840 2298 16 x 68 = 1088 effective -i value = 4352 9775 40 x 32 = 1280 effective -i value = 5120 9771 16 x 84 = 1344 effective -i value = 5376 RP07 50 x 32 = 1600 effective -i value = 6400 Thus on a big disk, you have to decrease the number of cylinder groups if you need lots of inodes. Mkfs doesn't tell you this, though. So you see that the newfs default for "-i" is usually not only unrealistic, but a false promise as well. For the disks most people use (Eagle or RA81), -i 4096 is a more truthful value. My point was that newfs, which is supposedly a ``friendly'' preprocessor for mkfs's long argument list, ought to compute things like -i, -b, -f, -c, and maybe -m from a single novice- understandable number, the expected average file size. Anyone can divide the numbers from "df -i" output, or from a count of files and megabytes on a distribution tape. And isn't this the figure that really determines what settings are optimal? Don Speck speck@cit-vax.arpa