Path: utzoo!mnetor!uunet!husc6!mailrus!ames!pasteur!ucbvax!decvax!mandrill!hal!ncoast!allbery
From: allbery@ncoast.UUCP (Brandon Allbery)
Newsgroups: comp.unix.wizards
Subject: Re: Compressing unix disks
Message-ID: <7582@ncoast.UUCP>
Date: 3 Apr 88 18:13:51 GMT
References: <1071@ndmath.UUCP> <2452@umd5.umd.edu> <305@marconi.SW.MCC.COM> <1097@hubcap.UUCP> <208@hotlr.ATT> <5949@cit-vax.Caltech.Edu>
Reply-To: allbery@ncoast.UUCP (Brandon Allbery)
Followup-To: comp.unix.wizards
Organization: Cleveland Public Access UN*X, Cleveland, Oh
Lines: 22

As quoted from <5949@cit-vax.Caltech.Edu> by mangler@cit-vax.Caltech.Edu (Don Speck):
+---------------
> (long discussion of BSD filesystems deleted)
| (I wonder how a free space reserve affects SysV, Counterpoint & Masscomp
| filesystems)?
+---------------

It doesn't affect System V very much at all:  the "old-style" filesystem
doesn't have to keep track of fragments and the free list is kept in such a
way that either the first block in the free list is available or the file
system is full.  No degradation on full filesystems at the price of being
slightly slower overall -- much *faster* on the systems I use, but then you
seem to need CPU to use the Berkeley FFS, and System V is popular on the
little *nix boxes.

A free space reserve *is* a good idea on the pipedev, though:  at least under
System III, the system just about stops dead when it can't allocate a block
for a pipe.  (Even though one would think that pipe blocks would remain in
the cache insteda of on disk -- is this a System III bug?)
-- 
	      Brandon S. Allbery, moderator of comp.sources.misc
       {well!hoptoad,uunet!hnsurg3,cbosgd,sun!mandrill}!ncoast!allbery