[TUHS] /dev/drum

[rudi.j.blom@gmail.com (Rudi Blom)]

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>Date: Mon, 23 Apr 2018 13:51:07 -0400
>From: Clem Cole <clemc at ccc.com>
>To: Ron Natalie <ron at ronnatalie.com>
>Cc: Tim Bradshaw <tfb at tfeb.org>, TUHS main list <tuhs at minnie.tuhs.org>
>Subject: Re: [TUHS] /dev/drum
>Message-ID:
>        <CAC20D2PEzAayjfaQN+->kQS=H7npcEZ_OKXL1ffPxak5b2ENv4Q at mail.gmail.com>
>Content-Type: text/plain; charset="utf-8"

... some stuff removed ...

>​Exactly...   For instance an RK04 was less that 5K blocks (4620 or some
>such - I've forgotten the actually amount).  The disk was mkfs'ed to the
>first 4K and the left over was give to the swap system.   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.

Wondered why, but I guess now I know that's the reason Digital UNIX on
alpha used the same disk layout. From a AlphaServer DS10 running
DU4.0g, output "disklabel -r rz16a"

# /dev/rrz16a:
type: SCSI
disk: BB009222
label:
flags:
bytes/sector: 512
sectors/track: 168
tracks/cylinder: 20
sectors/cylinder: 3360
cylinders: 5273
sectors/unit: 17773524
rpm: 7200
interleave: 1
trackskew: 66
cylinderskew: 83
headswitch: 0		# milliseconds
track-to-track seek: 0	# milliseconds
drivedata: 0

8 partitions:
#          size     offset    fstype   [fsize bsize   cpg]      #
NOTE: values not exact
  a:     524288          0     AdvFS                    	# (Cyl.    0 - 156*)
  b:    1572864     524288      swap                    	# (Cyl.  156*- 624*)
  c:   17773524          0    unused        0     0       	# (Cyl.    0 - 5289*)
  d:          0          0    unused        0     0       	# (Cyl.    0 - -1)
  e:          0          0    unused        0     0       	# (Cyl.    0 - -1)
  f:          0          0    unused        0     0       	# (Cyl.    0 - -1)
  g:    4194304    2097152     AdvFS                    	# (Cyl.  624*- 1872*)
  h:   11482068    6291456     AdvFS                    	# (Cyl. 1872*- 5289*)