Looking for rationale of fs naming conventions

[Warren Toomey]

> 	Thanks Eric....  that sort of discussion makes my day, and feeds my
> 	woefully short history folder, nicely!  Does anything in print cover
> 	this sort of thing in one place?
>
> 	Bob Keys

As with much of early Unix, you have to Use the Source, Luke. Small disks
like the RK05s and RL02 were not typically partitioned, except to put a
swap space at one end. However, bigger disks like the RP04s were. In V6
and V7, this was done by the device driver, and the device minor number
represented the particular partition, e.g from v6 hp.c

struct {
        char    *nblocks;
        int     cyloff;
} hp_sizes[] {
        9614,   0,              /* cyl 0 thru 23 */
                                /* cyl 24 thru 43 available */
        -1,     44,             /* cyl 44 thru 200 */
        -1,     201,            /* cyl 201 thru 357 */
        20900,  358,            /* cyl 358 thru 407 */
                                /* cyl 408 thru 410 blank */
        40600,  0,
        40600,  100,
        40600,  200,
        40600,  300,
};

. . .

hpstrategy(abp)
struct buf *abp;
{
        register struct buf *bp;
        register char *p1, *p2;

        bp = abp;
        p1 = &hp_sizes[bp->b_dev.d_minor&07];

Here, each of the 8 minor device numbers selected a different set of
cylinders on the disk, and note also that some of the sets overlapped.
The V6 manual on hp(4) says:

	Since  the  disk is so large, this allows it to be broken
	up into more manageable pieces. The origin and size of the
	pseudo-disks on each drive are as follows:
     			disk start     length
     			0    0 	       9614
     			1    18392     65535
     			2    48018     65535
     			3    149644    20900
     			4    0 	       40600
     			5    41800     40600
     			6    83600     40600
     			7    125400    40600 
	It is unwise for all of these files to be present in one
	installation, since there  is  overlap  in  addresses and
	protection becomes a sticky matter.

Early versions of BSD followed this compile-time partition selection.
I'm note sure when disklabels appeared, perhaps in 4.2BSD. Kirk or
Steven might be able to tell us.

	Warren

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