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[107.215.223.229]) by smtp.gmail.com with ESMTPSA id j4-20020a170902c3c400b001d395d3df30sm19090245plj.130.2023.12.31.16.13.13 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sun, 31 Dec 2023 16:13:14 -0800 (PST) From: Bakul Shah Message-Id: Content-Type: multipart/alternative; boundary="Apple-Mail=_0210F380-D79B-4E1A-9C82-A5D380CD91F3" Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.300.61.1.2\)) Date: Sun, 31 Dec 2023 16:13:02 -0800 In-Reply-To: To: Warner Losh References: <6470c59f-a1e5-418f-803d-76bcd761f530@tnetconsulting.net> <202312311738.3BVHctA1018336@freefriends.org> X-Mailer: Apple Mail (2.3774.300.61.1.2) Message-ID-Hash: NG5F6VDDVE4BOXQF3H63LM27BHBBL2YZ X-Message-ID-Hash: NG5F6VDDVE4BOXQF3H63LM27BHBBL2YZ X-MailFrom: bakul@iitbombay.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: tuhs@tuhs.org, gtaylor@tnetconsulting.net X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] Re: Question about BSD disklabel history List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --Apple-Mail=_0210F380-D79B-4E1A-9C82-A5D380CD91F3 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 On Dec 31, 2023, at 12:07=E2=80=AFPM, Warner Losh = wrote: >=20 > 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. > =20 >> 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. >>=20 >> 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. >=20 > 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.= --Apple-Mail=_0210F380-D79B-4E1A-9C82-A5D380CD91F3 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
On Dec 31, 2023, at 12:07=E2=80=AFPM, = 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.
= --Apple-Mail=_0210F380-D79B-4E1A-9C82-A5D380CD91F3--