Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!ukma!rex!ginosko!husc6!rice!sun-spots-request From: chris@mimsy.umd.edu (Chris Torek) Newsgroups: comp.sys.sun Subject: Re: partitions (bad idea ??) Keywords: SunOS Message-ID: <609@brazos.Rice.edu> Date: 28 Jul 89 10:01:09 GMT Sender: root@rice.edu Organization: Sun-Spots Lines: 46 Approved: Sun-Spots@rice.edu X-Sun-Spots-Digest: Volume 8, Issue 88, message 9 of 16 eho@cognito.princeton.edu (Eric Ho) asks: >Has anyone out there worked on filesystems that either eliminates >partitions. (Either that or what?) >The only reason that I can see to have the notion of partitions around >from the OS standpoint is to limit filesystem size (& to make a filesystem) >and maybe easier for doing backups. A disk has a size. (I think no one can disagree with this.) Unless you concatenate disks---which is possible; Convex, for instance, have this ability in their kernels---there is thus a hard limit on file system size, namely the size of the disk. All that partitions do is allow you, the system administrator, to divide that hard limit into several smaller hard limits. They do NOT *require* that you do so. The main reason for partitions is to limit file system size (adminstrators may have their own reasons for doing this; the kernel does not care, so long as the FS sizes fit in the 32 bit numbers the kernel uses) and/or to create separate file systems on a single physical medium. >... I mean if I want to expand one partition/filesystem into the >space previously occupied by another partition/filesystem, why should I've >to go thro' all the backup/restore hassels. Clearly the one that is being expanded into will have to be saved first, because the expansion process will overwrite it. The other file system need not be backed-up, but its size is maintained statically, so it will never notice the extra space unless you re-create it. It is not necesssary to reformat, but it is necessary to run newfs. The real question here may be `why is it necessary to run newfs?' Well, you could write a `dynamic' file system in which it was not necessary. You will lose some performance in the process. Given that I change file system sizes less often than once a year, I would rather have the performance. Or, you could write a special version of `newfs' that carefully expands an existing file system without disturbing any of the data contained therein (except of course the free block maps and cylinder group summaries). There are some constraints on how well this would work, but I imagine it would make a good project for someone. In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163) Domain: chris@mimsy.umd.edu Path: uunet!mimsy!chris