Looking for rationale of fs naming conventions

User Rdkeys Robert D. Keys rdkeys at seedlab1.cropsci.ncsu.edu
Tue Sep 8 04:10:42 AEST 1998

> The `diskpart' utility was used in 4.4BSD to organize disk partitions.
> Its manual page tries to rationalize the use of partitions. I enclose
> it below in case you do not have access to it.
> 	Kirk McKusick


A couple of more questions, so I get the entire picture.....since you
were there.... as the old TV show went.....

>      In normal opera-
>      tion, either the `g' partition is used, or the `d', `e', and `f' parti-
>      tions are used.  The `g' and `f' partitions are variable-sized, occupying
>      whatever space remains after allocation of the fixed sized partitions.

What are d,e, and f partititions typically used for or originally designed
for, as opposed to g?  I see some of the historical carryovers in how they
were arrived at, but I sense there was probably some reasoning or design
advantages one way over another, back in time, or else there would not
have been the distinctions.

>      Partition   20-60 MB   61-205 MB   206-355 MB   356+ MB
>      a           15884      15884       15884        15884
>      b           10032      33440       33440        66880
>      d           15884      15884       15884        15884

d is a small partition, so what would it have been designed to be used for?
It seems the same as root in size, so would it have been, for example, a
spare root copy?

>      e           unused     55936       55936        307200

e is variable in size, and the only use I have seen of it is for the /var fs,
so, what was e designed for, or typically used as?

>      h           unused     unused      291346       291346

Likewise for h.

In my limited exposure, I have seen in 4.3BSD that g was typically used for
the /usr partition as the rest of the disk.  On 4.4BSD, /var was hung on e
and g was the usr partition for the rest of the disk, on one setup, and on
another things were really confused and var was hung on h, with all different
kinds of other fs hung out here and there across the disks.  The rationale
for it was, at best, confusing to the newbie.

Is it particularly important to worry about how it is laid out, or in the
Berkeley tradition, are there particular advantages or economies to laying
it out with d/e/f/ as opposed to just g?  I see the fs loading table in
the 4.4 install guide, but was wondering if there was more to it than that.

>      Most default partition sizes are based on historical artifacts (like the
>      RP06), and may result in unsatisfactory layouts.

This is what I am seeing, it would appear.

Maybe the advantages of earlier layouts vs disks are becoming lost with the
modern megadisks, in many instances.  Also, I tend to see things from the
point of view of a single user workstation as opposed to a big multiuser
server of some kind.  Thus, my frame of refernce is a little skewed.


Bob Keys

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