Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!uunet!olivea!apple!agate!stanford.edu!neon.Stanford.EDU!calvin!zimmer From: zimmer@calvin.stanford.edu (Andrew Zimmerman) Newsgroups: comp.sys.next Subject: Re: Misc questions Message-ID: <1991Mar5.113934.1691@neon.Stanford.EDU> Date: 5 Mar 91 11:39:34 GMT References: Sender: news@neon.Stanford.EDU (USENET News System) Organization: Stanford University Lines: 74 In article scott@erick.gac.edu (Scott Hess) writes: >In article aberno@questor.wimsey.bc.ca (Anthony Berno) writes: > 1) When you add the size of root (found by using the Inspector panel in the > workspace) with the amount of free space on the disk, is it supposed to > total the size of the disk? I am short by about 80 meg on a 660 meg disk. >A big culprit would be the version of du (or the du-like functionality) >provided by the Workspace Inspector panel. The default du(1) utility >provided gives the disk usage in bytes. This is misleading because >few files require an integral number of blocks and fragments - most >leave some free at the end of their frags. Thus, on average, if the >number of files in the system is n, the amount of data "lost" to >the space at the end of fragments is n*frag_size/2. >Later, >-- >scott hess scott@gac.edu >Independent NeXT Developer GAC Undergrad While what Scott answered was true, there is another factor which might be causing some of the confusion. The unix fs reserves 10% of the size of the formatted disk to improve performance. This would be about 66 Megs on the 660 Meg disk. So, we have 790 - unformatted 660 - formatted 594 - unix file system The following is an attempt to be helpful. Since I have not tried this myself, please use at your own risk: "You can tune a fish, and you can tune a file system" or "How to nuke your filesystem" tunefs(8) Name tunefs - tune up an existing file system Syntax /etc/tunefs [ options ] Description The tunefs command is designed to change the dynamic parameters of a file system which affect the layout policies. The parame- ters which are to be changed are indicated by the options listed below: Options -m minfree This value specifies the percentage of space held back from normal users; the minimum free space threshold. The default value used is 10%. This value can be set to zero, however up to a factor of three in throughput will be lost over the performance obtained at a 10% threshold. Note that if the value is raised above the current usage level, users will be unable to allocate Restrictions This program should work on mounted and active file systems. Because the super-block is not kept in the buffer cache, the pro- gram will only take effect if it is run on dismounted file sys- tems. If run on the root file system, the system must be rebooted. I have left off all of the options other then the one that might have a direct effect on the original problem. Note: Don't blame me if something goes wrong. I have no reason to think that something will go wrong, I'm just being careful. Andrew zimmer@calvin.stanford.edu