From: Bakul Shah <bakul@iitbombay.org>
To: Warner Losh <imp@bsdimp.com>
Cc: tuhs@tuhs.org, gtaylor@tnetconsulting.net
Subject: [TUHS] Re: Question about BSD disklabel history
Date: Sun, 31 Dec 2023 16:13:02 -0800 [thread overview]
Message-ID: <F1DE9F77-F2C8-4647-9F22-565D173A8071@iitbombay.org> (raw)
In-Reply-To: <CANCZdfrGThzgP=QjrS-cuxj5knRg0LGe+M7H801wJAtRSwt2xA@mail.gmail.com>
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On Dec 31, 2023, at 12:07 PM, Warner Losh <imp@bsdimp.com> wrote:
>
> Yes. Unlike today, the partitions covered the disk in different, overlapping
> ways. And allowed for some parts of the disk to be uncovered by a
> partition. You could then patch the offset and length into the kernel with
> adb and use that area of the disk for swap space.
>
>> It was also helpful, if you had the drives, to nightly dd
>> your real root to the "a" partition on another, identical
>> drive, so that you could boot the backup root in an emergency.
>>
>> I don't remember for sure, but I think that Ultrix may have
>> been the first BSD-style system to have disk labels, followed
>> by some version of SunOS. All of that is way in the distant
>> past though: mid- to late 80's.
>
> When I looked into it years ago, I convinced myself that SunOS
> was the first to have it (since the very first version of SunOS 1.0
> had disk labels) and that all the other vendors followed suit within
> a couple of years. Ultrix-11 had the fixed labels through its EOL.
> I didn't see any disklable stuff in the Ultrix-32M that we have, but
> it was admittedly a quick look.
I wrote the first 2-3 HD drivers for Fortune Systems. I had
the first one up and running[1] by late 1981. IIRC we used an
ioctl to read/write sector 0 of a disk, which is where we
stored partition info. I think by 1983 we were using some
4.1a bits (or at least influenced by it) so likely disklabel
was used by then. The first disk drive was 5MB and cost
$1700. But 5 1/4" disk capacities were growing fast so there
was no question of hardwiring a disktab in source code. I
even had a program that would try to "step" through cylinders
until it ran into errors, to find at usable capacity!
[1] Well, more like walking! Initially DMA didn't work on the
first wirewrap boards so had to use PIO (programmed IO),
at 25KB/s. A quick hack doubled that performance, while
an ST506 disk could do 5Mbits/sec.
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next prev parent reply other threads:[~2024-01-01 0:13 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-31 17:30 [TUHS] " Grant Taylor via TUHS
2023-12-31 17:38 ` [TUHS] " arnold
2023-12-31 20:07 ` Warner Losh
2024-01-01 0:13 ` Bakul Shah [this message]
2023-12-31 20:27 ` Phil Budne
2023-12-31 21:02 ` Warner Losh
2024-01-01 0:26 ` Grant Taylor via TUHS
2024-01-01 2:22 ` Warner Losh
2024-01-01 3:24 ` Grant Taylor via TUHS
2023-12-31 21:31 ` Clem Cole
2023-12-31 22:07 ` Warner Losh
2024-01-01 16:00 ` Clem Cole
2024-01-02 18:49 ` Warner Losh
2024-01-02 19:30 ` Chet Ramey
2024-01-02 20:07 ` Clem Cole
2024-01-02 19:50 ` Dan Cross
2024-01-02 19:55 ` Jim Capp
2024-01-02 20:11 ` Dan Cross
2024-01-02 20:30 ` Dan Cross
2024-01-02 20:50 ` Clem Cole
2024-01-02 21:04 ` Dan Cross
2023-12-31 22:46 ` G. Branden Robinson
2023-12-31 23:06 ` Larry McVoy
2023-12-31 23:37 ` Al Kossow
2023-12-31 23:41 ` Alec Muffett
2024-01-02 20:48 ` Dan Cross
2024-01-02 21:17 ` John Cowan
2024-01-03 3:33 ` Theodore Ts'o
2024-01-03 3:57 ` Warner Losh
2024-01-03 4:03 ` Warner Losh
2024-01-03 4:30 ` Theodore Ts'o
2024-01-03 5:10 ` Warner Losh
2024-01-03 15:56 ` Dan Cross
2024-01-03 16:37 ` Theodore Ts'o
2024-01-03 16:41 ` Dan Cross
2024-01-04 8:42 ` arnold
2024-01-04 18:26 ` Kevin Bowling
2024-01-03 14:39 ` Dan Cross
2023-12-31 23:08 ` Phil Budne
2023-12-31 23:37 ` G. Branden Robinson
2023-12-31 23:59 ` Warner Losh
2023-12-31 23:50 ` G. Branden Robinson
2024-01-01 0:09 ` Al Kossow
2023-12-31 21:55 Norman Wilson
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