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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.unix-wizards
Subject: Re: Location of partition table on disk
Message-ID: <7289@utzoo.UUCP>
Date: Wed, 5-Nov-86 17:58:29 EST
Article-I.D.: utzoo.7289
Posted: Wed Nov  5 17:58:29 1986
Date-Received: Wed, 5-Nov-86 17:58:29 EST
References: <131@houligan.UUCP>
Organization: U of Toronto Zoology
Lines: 26

> ... A partition table should contain the following:
> 
> ... (maybe) a flag indicating
>   what sort of bad block replacement algorithim is in use ...
> 
> a flag for each partition indicating what sort of thing the partition is
>   (BSD partition, SYS-V partition, raw data, swap, etc)...

I implore anyone doing something like this to implement those "flags" as
space for a short character string, *not* as a one-byte magic number.
Using character strings doesn't eliminate the administrative problems of
making sure that the same code doesn't get used for two different things,
but it makes them a whole lot less likely.

Note also that 4BSD filesystems can be 4KB or 8KB, SysV filesystems can
be 512B or 1KB, and V8 filesystems can be 1KB or 4KB... to mention just
a few variations that should be described.

> a volume or set number, for implementing multivolume file systems (for
>   instance, Chris Torek's striping setup).

This is more complex than it looks; striping requires more information
than that, at least in principle.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,decvax,pyramid}!utzoo!henry