From: clemc@ccc.com (Clem Cole)
Subject: [TUHS] /dev/drum
Date: Mon, 23 Apr 2018 17:27:29 -0400 [thread overview]
Message-ID: <CAC20D2Pd+pn=SwYxZJChXHowM1K10-k0QwWqsy3qe96e-EOP6Q@mail.gmail.com> (raw)
In-Reply-To: <4b95c9f6-0190-be93-7284-d03be289c4ba@gmail.com>
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On Mon, Apr 23, 2018 at 5:14 PM, Dan Mick <danmick at gmail.com> wrote:
> On 04/23/2018 02:06 PM, Clem Cole wrote:
> >
> >
> > On Mon, Apr 23, 2018 at 4:47 PM, Grant Taylor via TUHS
> > <tuhs at minnie.tuhs.org <mailto:tuhs at minnie.tuhs.org>> wrote:
> >
> > On 04/23/2018 11:51 AM, Clem Cole wrote:
> >
> > By the time of 4.X, the RP06 was 'partitioned' into 'rings'
> > (some overlapping). The 'a' partition was root, the 'b' was
> > swap and one fo the others was the rest. Later the 'c' was a
> > short form for copying the entire disk.
> >
> >
> > I had always wondered where Solaris (SunOS) got it's use of the
> > different slices, including the slice that was the entire disk from.
> >
> > Now I'm guessing Solaris got it from SunOS which got it from 4.x BSD
> >
> > It was not BSD - it was research. It may have been in 6th, but it was
> > definitely in 7th. Cut/pasted from the V7 PDP-11 rp(4) man page:
> >
> > *NAME*
> >
> > rp − RP-11/RP03 moving-head disk
> >
> > *DESCRIPTION*
> >
> > The files rp0 ... rp7 refer to sections of RP disk drive 0. The
> > files rp8 ... rp15 refer to drive 1 etc. This
> >
> > allows a large disk 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 81000
> >
> > 1 0 5000
> >
> > 2 5000 2000
> >
> > 3 7000 74000
> >
> > 4-7 unassigned
> >
> > Thus rp0 covers the whole drive, while rp1, rp2, rp3 can serve
> > usefully as a root, swap, and mounted user
> >
> > file system respectively.
> >
> > The rp files access the disk via the system’s normal buffering
> > mechanism and may be read and written
> >
> > without regard to physical disk records. There is also a ‘raw’
> > interface which provides for direct transmission
> >
> > between the disk and the user’s read or write buffer. A single
> > read or write call results in exactly one
> >
> > I/O operation and therefore raw I/O is considerably more
> > efficient when many words are transmitted. The
> >
> > names of the raw RP files begin with rrp and end with a number
> > which selects the same disk section as the
> >
> > corresponding rp file.
> >
> > In raw I/O the buffer must begin on a word boundary.
> >
> > ᐧ
>
> But...that has numbers, not letters, and the third partition is not the
> whole drive, the first one is....?
>
Yup -- disk were pretty expensive in those days ($20-30K for a <100M drive)
so often people did not have more than one. So they started with rp1, rp2
etc..
As disks dropped a little cheaper and having more than one RP06 became
possible (RP06 aka IBM 3330 - project Winchester -- was a huge 200M drive
- we had 3 on the Teklabs machine and that was considered very, very
generous), then letters became the convention used in /dev/. i.e.
/dev/{,r}rp0{a,b,c,d..} for each of the minor numbers.
To be honest, I really don't remember - but I know we used letters for the
different partitions on the 11/70 before BSD showed up.
The reason for the partition originally was (and it must have been 6th
edition when I first saw it), DEC finally made a disk large enough that
number of blocks overflowed a 16 bit integer. So splitting the disk into
smaller partitions allowed the original seek(2) to work without overflow.
V7 introduced lseek(2) when the offset was a long.
Clem
ᐧ
ᐧ
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next prev parent reply other threads:[~2018-04-23 21:27 UTC|newest]
Thread overview: 117+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-20 15:02 Tim Bradshaw
2018-04-20 15:58 ` Clem Cole
2018-04-20 16:00 ` David Collantes
2018-04-20 16:12 ` Dan Cross
2018-04-20 16:21 ` Clem Cole
2018-04-20 16:33 ` Warner Losh
2018-04-20 19:17 ` Ron Natalie
2018-04-20 20:23 ` Clem Cole
2018-04-20 22:10 ` Dave Horsfall
2018-04-22 17:01 ` Lars Brinkhoff
2018-04-22 17:37 ` Clem Cole
2018-04-22 19:14 ` Bakul Shah
2018-04-22 20:58 ` Mutiny
2018-04-22 22:37 ` Clem cole
2018-04-22 21:51 ` Dave Horsfall
2018-04-25 1:27 ` Dan Stromberg
2018-04-25 12:18 ` Ronald Natalie
2018-04-25 13:39 ` Tim Bradshaw
2018-04-25 14:02 ` arnold
2018-04-25 14:59 ` tfb
2018-04-25 14:33 ` Ian Zimmerman
2018-04-25 14:46 ` Larry McVoy
2018-04-25 15:03 ` ron minnich
2018-04-25 20:29 ` Paul Winalski
2018-04-25 20:45 ` Larry McVoy
2018-04-25 21:14 ` Lawrence Stewart
2018-04-25 21:30 ` ron minnich
2018-04-25 23:01 ` Bakul Shah
2018-04-23 16:42 ` Tim Bradshaw
2018-04-23 17:30 ` Ron Natalie
2018-04-23 17:51 ` Clem Cole
2018-04-23 18:30 ` Ron Natalie
2018-04-25 14:02 ` Tom Ivar Helbekkmo
2018-04-25 14:38 ` Clem Cole
2018-04-23 20:47 ` Grant Taylor
2018-04-23 21:06 ` Clem Cole
2018-04-23 21:14 ` Dan Mick
2018-04-23 21:27 ` Clem Cole [this message]
2018-04-24 3:28 ` [TUHS] 3330s, 3340s, Winchesters... (was: /dev/drum) Greg 'groggy' Lehey
2018-04-24 11:43 ` Paul Winalski
2018-04-24 13:13 ` Clem Cole
2018-04-25 0:52 ` Greg 'groggy' Lehey
2018-04-25 20:54 ` Paul Winalski
2018-04-23 22:07 ` [TUHS] /dev/drum Tim Bradshaw
2018-04-23 22:15 ` Warner Losh
2018-04-23 23:30 ` Grant Taylor
2018-04-24 9:37 ` Michael Kjörling
2018-04-24 9:57 ` Dave Horsfall
2018-04-24 13:01 ` Nemo
2018-04-24 13:03 ` Arthur Krewat
2018-04-25 1:31 ` [TUHS] Disk data layout (was: /dev/drum) Greg 'groggy' Lehey
2018-04-25 6:43 ` Hellwig Geisse
2018-04-25 21:17 ` Paul Winalski
2018-04-25 21:55 ` Bakul Shah
2018-04-27 15:47 ` Dave Horsfall
2018-04-27 18:16 ` Paul Winalski
2018-04-27 18:37 ` Clem Cole
2018-04-23 23:45 ` [TUHS] /dev/drum Arthur Krewat
2018-04-24 8:05 ` tfb
2018-04-20 16:45 Noel Chiappa
2018-04-20 16:53 ` Charles Anthony
2018-04-20 17:16 ` William Pechter
2018-04-20 23:35 ` Dave Horsfall
2018-04-22 11:48 ` Steve Simon
2018-04-22 18:06 Norman Wilson
2018-04-23 18:41 Noel Chiappa
2018-04-23 19:09 ` Clem Cole
2018-04-23 23:01 ` Dave Horsfall
2018-04-23 23:49 ` Dave Horsfall
2018-04-24 0:26 ` Ronald Natalie
2018-04-23 22:01 Noel Chiappa
2018-04-23 22:09 ` Warner Losh
[not found] <mailman.125.1524526228.3788.tuhs@minnie.tuhs.org>
2018-04-23 23:44 ` Johnny Billquist
2018-04-23 23:57 ` Steve Nickolas
2018-04-24 0:24 ` Ronald Natalie
2018-04-24 0:25 ` Warren Toomey
2018-04-24 0:31 ` Dave Horsfall
2018-04-24 1:02 ` Lyndon Nerenberg
2018-04-24 4:32 ` Grant Taylor
2018-04-24 4:49 ` Bakul Shah
2018-04-24 4:59 ` Warner Losh
2018-04-24 6:22 ` Bakul Shah
2018-04-24 14:57 ` Warner Losh
2018-04-24 6:46 ` Lars Brinkhoff
2018-04-24 7:10 Rudi Blom
[not found] <mailman.137.1524667148.3788.tuhs@minnie.tuhs.org>
2018-04-25 21:43 ` Johnny Billquist
2018-04-25 22:24 ` Johnny Billquist
2018-04-26 5:51 ` Tom Ivar Helbekkmo
2018-04-25 22:37 ` Johnny Billquist
2018-04-25 22:46 Noel Chiappa
[not found] <mailman.139.1524690859.3788.tuhs@minnie.tuhs.org>
2018-04-25 22:54 ` Johnny Billquist
2018-04-25 22:55 Noel Chiappa
[not found] <mailman.143.1524696952.3788.tuhs@minnie.tuhs.org>
2018-04-25 23:08 ` Johnny Billquist
2018-04-26 1:53 Noel Chiappa
[not found] <mailman.1.1524708001.6296.tuhs@minnie.tuhs.org>
2018-04-27 22:41 ` Johnny Billquist
2018-04-27 23:01 Noel Chiappa
2018-04-27 23:10 ` Johnny Billquist
2018-04-27 23:39 ` Warner Losh
2018-04-28 0:19 Noel Chiappa
2018-04-28 10:41 ` Johnny Billquist
2018-04-28 12:19 ` Rico Pajarola
2018-04-28 20:40 Noel Chiappa
2018-04-29 15:37 ` Johnny Billquist
2018-04-29 16:34 ` Steve Nickolas
2018-04-29 16:48 ` Warner Losh
2018-04-30 15:05 Noel Chiappa
2018-04-30 16:43 ` Paul Winalski
2018-04-30 21:41 ` Johnny Billquist
2018-05-03 2:54 ` Charles Anthony
2018-05-03 11:39 Noel Chiappa
2018-05-03 21:22 ` Johnny Billquist
2018-05-05 13:06 Noel Chiappa
2018-05-05 20:53 ` Johnny Billquist
2018-05-06 13:07 Noel Chiappa
2018-05-06 15:57 ` Johnny Billquist
2018-05-07 15:36 Noel Chiappa
[not found] <mailman.1.1525744802.16322.tuhs@minnie.tuhs.org>
2018-05-08 22:39 ` Johnny Billquist
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