11 Jun
1998
11 Jun
'98
11:53 a.m.
In general, file systems seem to fit into several simple categories.
Let's say UNIX-like, DOS-like, simple (just data), and that's about it
I've looked at Apple manuals, and the Apple ][ format is kinda like
DOS in terms of having an array of blocks and stuff. Except Apple's
is quite a bit more elegant. Since some people here are fond of
praising the VAX, how does its file system work (typically)?
That used to be one of my interview questions for Unix programmers:
your
buggy program just created a filename with {control
characters, leading
dash (-), leading slash (/), '*', etc} in it. How do you delete it?
Does anybody collect file systems? That would be semi-useful for
somebody
doing data recovery. I have no idea what the Newton
"soup", for
example,
looks like. One of my favorites was the Regulus
(unix-like)
filesystem.
It maintained a bitmap of free blocks and could easily
allocate a
best-fit
contiguous region for your file (I think they had an
option to creat()
for
contiguity). This made file access *fast* when you
needed it. I still
find fragmentation a nightmare even on Linux.
-- Doug
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11 Jun
11 Jun
12:06 p.m.
On Thu, 11 Jun 1998, Max Eskin wrote:
In general, file systems seem to fit into several
simple categories.
Let's say UNIX-like, DOS-like, simple (just data), and that's about it
I've looked at Apple manuals, and the Apple ][ format is kinda like
DOS in terms of having an array of blocks and stuff. Except Apple's
is quite a bit more elegant. Since some people here are fond of
praising the VAX, how does its file system work (typically)?
The Newton "soup" is an object store rather than a directory hierarchy,
and you'll probably see that paradigm more often in the future. I think
Microsoft's "Cairo" road-map included turning the filesystem into an
object store.
"VAX" is a hardware architecture. Lots of people run Unix on VAXen.
But the VAX-philopsophy was extreme CISC, and that extended to the VAX/VMS
filesystem as well: record-based, with a zillion different file
attributes, built-in file versioning, etc. It was hierarchial, but mixed
with a clunky "volume" concept (something like DOS "C:", but with
longer
names).
-- Doug
12:09 p.m.
Let's say UNIX-like, DOS-like, simple (just data),
and that's about it
I've looked at Apple manuals, and the Apple ][ format is kinda like
DOS in terms of having an array of blocks and stuff. Except Apple's
is quite a bit more elegant. Since some people here are fond of
praising the VAX, how does its file system work (typically)?
The Vax was something different from Unix and Dos.
It had a bitmap to allow quick allocations. It also
had the ability to create contiguous files to suport real time
work.
It had a layer called RMS which gave it indexed file access. Kind
of like IBM mainframe stuff. Files could have a declared
record size like they do on mainframes.
Vax/VMS ODS-2 (the vax enhancement to the RDX11 ODS-1 file structure)
actually supported multiple directories, multiple directory roots (many
systems booting off different structures on one disk).
Someone here should be able to point to some ODS-2 docs on the web.
Bill
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