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From: HELMER%SDNET.BITNET@vm1.nodak.edu (Guy Helmer)
Newsgroups: comp.os.minix
Subject: Re: Large Disks
Message-ID: <24983@louie.udel.EDU>
Date: 3 Oct 89 14:46:32 GMT
Sender: mmdf@udel.EDU
Lines: 39

ast@CS.VU.NL writes:
>In article <233@vsserv.scri.fsu.edu> nall@nu.cs.fsu.edu (John Nall) writes:
>>Just as a start, if one does mkfs /dev/hd2 40000" for example,
>>an error occurs right off the bat, since the 40000 is read into
>>a integer variable called "blocks" and is thus a negative number.
>   ...
>>However, I would hope that with the release
>>of Minix Version 2.0, there would be a compilation parameter
>>(size_t??) which would allow a 32-bit integer to be used.

Since disks are getting fairly big, and since 24-bit integers are used by
Un*x to specify block numbers in inodes (see below), it seems Minix should
be coherent and allow for large disks in all the system utilities if the
file system is changed to allow it.

>As to 32 bit disk address, I don't know if you understand what you just
>said.  I suspect not.  Unfortunately, I know very well what you just said.
>I haven't brought the subject up yet because it is an unpleasant one, but
>invariably somebody else will see the problem too and bring it up, so I might
>as well go first.
>
>The MINIX i-node is 32 bytes.  This was designed to be frugal on a floppy
>based system.  The 32 bytes contain 9 16-bit disk addresses and a few other
>goodies.

If I need a 100Mb partition when I get C-news up, I'll need more bits for
block addresses in the inode :-) !  (Bigger blocks could be considered, but
lots of disk would be wasted on short news articles)

>What do people think about a 64-byte i-node with 3 times and 24-bit disk
>addresses (32-bits is overkill, and I'd rather have 13 addresses in the
>i-node, just like UNIX).  Due to the bit maps, the disk layout can't be
>UNIX compatible, however.
> ...
>
>Andy Tanenbaum (ast@cs.vu.nl)
-- Guy Helmer                                  AT&T: (605) 256-5315
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