[TUHS] Re: Question about BSD disklabel history

Disk sections (I don't think anyone in Research called them partitions--certainly the Research manuals didn't) were originally defined in the device driver, not by data on the disk. In those days, system management included recompiling stuff, including the OS kernel, and it was not unusual for sites to edit hp.c or whatnot to adjust things to local preference. There was nothing magic about the mapping between device names and minor device numbers either; the system came with certain conventions on the original tape, but it was not at all uncommon to change them. By the time I arrived at the first Unix site I ever helped run, in a physics group at Caltech, we already used a different naming convention: a BSD-like ddNs, where dd was a driver name, N the physical drive unit number, s a section letter. I don't know whether that was borrowed from BSD (it must have started during the 3BSD era, since I started there in mid-1980 and 4BSD appears to have been released late in that year). Looking at my archival copy of that much-locally-hacked source tree, I see that we later moved the definitions of all the disk-section tables to a single file compiled at system-configuration time (we used a USG-like scheme that compiled most of the system into libraries, rather than compiling every file separately for each target system a la V7 and BSD). That simplified handling our somewhat- complicated disk topology: all but system disks were connected through System Industries 9400 disk controllers, which were a neat design (each controller could interface to as many as four hosts and four disks) but in practice were not always reliable. On one hand, we arranged for one disk to be used in parts by our main time-sharing VAX and a subsidiary PDP-11/45, making the 11/45 cheaper to keep around; on the other, the main VAX had two paths to each of its disks, through different SI controllers, so when an SI controller conked out we could run without it until the service guys fixed it. (Each disk was dual-ported, as was common in the SMD world, hence connected to two controllers.) Reliability took rather more work in those days. A different data point: by the time I moved from California to New Jersey and joined 1127, Research was also using a different naming scheme for disk sections. By then the internal naming convention was e.g. ra17 for physical unit 1, section 7; by further convention 7 (the highest-numbered section). At some point a little later we added an ioctl to set the starting block and size of a particular section on a particular drive, but we never went to having the OS itself try to find a label and trust its contents (something that still makes the 1980s part of me feel a little creepy, though 21st century me has come to terms with it). Norman Wilson Certified old fart Toronto ON