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* [TUHS] mkfs somewhere else?
@ 2015-02-08  6:22 Jacob Ritorto
  2015-02-08  6:36 ` Dave Horsfall
  0 siblings, 1 reply; 12+ messages in thread
From: Jacob Ritorto @ 2015-02-08  6:22 UTC (permalink / raw)


Hi,
  I'm running 2.9BSD on a pdp11/34 with an Emulex sc21 controller to some
Fuji160 disks.  Booting with root on RL02 for now, but want to eventually
have the whole system on the Fujis and disconnect the rl02s.

  While the previous owner of the disks appears to have suffered a
headcrash near cylinder 0, I'm having an impressive degree of success
writing to other parts of the disk.

  However, when I try to mkfs, I can see the heads trying to write on the
headcrashed part of the disk.  (Nice having those plexiglass covers!)

  Is there a way to tell mkfs (or perhaps some other program) to not try to
write on the damaged cylinders?

thx
jake
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^ permalink raw reply	[flat|nested] 12+ messages in thread
* [TUHS] mkfs somewhere else?
@ 2015-02-08 20:10 Norman Wilson
  2015-02-12 15:29 ` Dave Horsfall
  0 siblings, 1 reply; 12+ messages in thread
From: Norman Wilson @ 2015-02-08 20:10 UTC (permalink / raw)


  Would anyone know if it's still possible to just replace the platters and
  clean the heads?

If the heads are really crashed, the only safe course is
to replace both the damaged heads and the damaged disk pack.
Anything else admits a substantial risk of carrying the
crash forward.

Cleaning the heads probably isn't an option; when they
crash, they don't just pick up material from the disk
platter, they may themselves be damaged enough that sharp
bits of the heads themselves are sticking out.

Norman Wilson
Toronto ON



^ permalink raw reply	[flat|nested] 12+ messages in thread
* [TUHS] mkfs somewhere else?
@ 2015-02-08 20:12 Norman Wilson
  0 siblings, 0 replies; 12+ messages in thread
From: Norman Wilson @ 2015-02-08 20:12 UTC (permalink / raw)


  what about using another minor device?  Is xp0d mapped elsewhere?

Since it's a BSD, won't it try by default to read a partition
table from the first few sectors of the disk?

Norman Wilson
Toronto ON



^ permalink raw reply	[flat|nested] 12+ messages in thread
* [TUHS] mkfs somewhere else?
@ 2015-02-08 20:20 Norman Wilson
  0 siblings, 0 replies; 12+ messages in thread
From: Norman Wilson @ 2015-02-08 20:20 UTC (permalink / raw)


Dave Horsfall:

  I also wrote a paper on a "bad block" system, where something like inum
  "-1" contained the list of bad sectors, but never saw it through.

====

During the file system change from V6 to V7, the i-number of
the root changed from 1 to 2, and i-node 1 became unused.
At least some versions of the documentation (I am too harried
to look it up at the moment) claimed i-node 1 was reserved
for holding bad blocks, to keep them out of the free list,
but that the whole thing was unimplemented.

I vaguely remember implementing that at some point: writing
a tool to add named sectors to i-node 1.  Other tools needed
fixing too, though: dump, I think, still treated i-node 1
as an ordinary file, and tried to dump the contents of
all the bad blocks, more or less defeating the purpose.

I left all that behind when I moved to systems with MSCP disks,
having written my own driver code that implemented DEC's
intended port/class driver split, en passant learning how
to inform the disk itself of a bad block so it would hide it
from the host.

I'd write more but I need to go down to the basement and look
at one of my modern* 3TB SATA disks, which is misbehaving
even though modern disks are supposed to be so much better ...

Norman Wilson
Toronto ON

* Not packaged in brass-bound leather like we had in the old days.
You can't get the wood, you know.



^ permalink raw reply	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2015-02-12 19:18 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-02-08  6:22 [TUHS] mkfs somewhere else? Jacob Ritorto
2015-02-08  6:36 ` Dave Horsfall
2015-02-08  7:03   ` Jacob Ritorto
2015-02-08  7:15     ` Jacob Ritorto
2015-02-08 17:34       ` Dave Horsfall
2015-02-08 18:52         ` Jacob Ritorto
2015-02-08 20:10 Norman Wilson
2015-02-12 15:29 ` Dave Horsfall
2015-02-12 15:50   ` cowan
2015-02-12 19:18     ` random832
2015-02-08 20:12 Norman Wilson
2015-02-08 20:20 Norman Wilson

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