tony@ur-cvsvax.UUCP (Tony Movshon) (01/28/85)
[!]
While the topic of MSDOS disk segment sizes, cluster allocation tables,
and so forth is current, let me offer the following cautionary tale:
I use a DEC Rainbow under DOS 2.05; I acquired a 10-megabyte hard
disk. In error, I used a formatting/partitioning program designed for a
5-megabyte disk. This program permitted me to create a single DOS
partition of 10 megabytes. The Rainbow uses a 2 kbyte cluster, which
with a 12-bit FAT yields 8 megabytes. But I did not do this arithmetic
until ...
... one day, I filled my disk beyond 8 megabytes. It was, in fact, a
large operation, creating about 500 kbytes of files, that did the trick.
Lo and behold, the ENTIRE hard disk was trashed. My interpretation is
that the 12-bit table simply overflowed, and the ninth megabyte
overwrote the first. Since the beginning of the disk contained the
roots of all my directory trees, that was it. Poof!
Now, Microsoft can restrict disks to any size it wants. But to
permit THIS to happen is ridiculous! To be fair, I'm not sure whether
the blame for this should go to Microsoft or to DEC, who presumably
wrote some of the code and the disk driver, and who provided the
formatting program that happily created the 10 megabyte partition.
Presumably, we could find out by creating inappropriate partitions for
other versions of DOS, but I can't imagine that anyone would really want
to ...
Tony Movshon, Dept. of Psychology, NYU, NYC 10003
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