From: Larry McVoy <lm@mcvoy.com>
To: Dave Horsfall <dave@horsfall.org>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] VFS prior to 1984
Date: Sat, 4 Jul 2020 17:16:09 -0700 [thread overview]
Message-ID: <20200705001609.GO29318@mcvoy.com> (raw)
In-Reply-To: <alpine.BSF.2.21.9999.2007050939520.455@aneurin.horsfall.org>
On Sun, Jul 05, 2020 at 10:05:57AM +1000, Dave Horsfall wrote:
> On Wed, 24 Jun 2020, Larry McVoy wrote:
>
> >>In the end, early NFS was notorious for putting 'holes' in the files
> >>because of the automatic seek in every operation and errors not coming
> >>until close(2) time.
> >
> >You have no idea how many of those holes that 16 bit SCCS checksum has
> >found (BitKeeper kept it).
>
> Aren't holes part of the file system semantics?
I'm not talking about legit holes, I'm talking about where your data used
be served up as a list of zeros.
The SCCS checksum is weak but kinda handy. You could see single bit errors
with it (at least you could in BitKeeper). It would say
checksum error: wanted %d, got %d
and you could look at the numbers and see that it was one bit off.
We found a bunch of those because computers used to be ECC or parity and
then 15 years ago or so, they just dumped the parity bit so single bit
errors go unreported (noice, computer industry).
next prev parent reply other threads:[~2020-07-05 0:17 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 9:09 Paul Ruizendaal
2020-06-23 14:01 ` Larry McVoy
2020-06-23 15:12 ` Clem Cole
2020-06-23 15:55 ` Rich Morin
2020-06-23 20:38 ` Rob Pike
2020-06-23 20:57 ` Larry McVoy
2020-06-24 5:14 ` arnold
2020-06-24 21:08 ` Dave Horsfall
2020-06-24 19:30 ` Clem Cole
2020-06-24 19:36 ` Larry McVoy
2020-06-25 6:52 ` Rob Gingell
2020-07-05 0:05 ` Dave Horsfall
2020-07-05 0:16 ` Larry McVoy [this message]
2020-07-06 4:42 ` Dave Horsfall
2020-07-06 16:51 ` Chris Torek
2020-07-06 23:23 ` [TUHS] ECC memory John Gilmore
2020-07-07 1:07 ` [TUHS] VFS prior to 1984 Bakul Shah
2020-07-05 1:43 ` Clem Cole
2020-07-05 14:43 ` Larry McVoy
2020-07-05 18:40 ` Arthur Krewat
2020-07-05 20:08 ` Clem Cole
2020-07-05 20:42 ` John Cowan
2020-07-05 21:04 ` Clem Cole
2020-07-05 21:14 ` Dan Cross
2020-06-24 16:51 ` Anthony Martin
2020-06-24 17:31 ` Anthony Martin
2020-06-24 18:31 ` Paul Ruizendaal
2020-06-25 0:56 ` Rob Gingell via TUHS
2020-06-25 4:15 ` [TUHS] Oh, things were very different Rich Morin
2020-06-25 15:45 ` Lawrence Stewart
2020-06-25 16:24 ` Warner Losh
2020-06-25 17:57 ` Arthur Krewat
2020-06-25 20:22 ` Dave Horsfall
2020-06-25 20:42 ` Michael Kjörling
2020-06-25 20:49 ` Clem Cole
2020-06-26 0:48 ` Dave Horsfall
2020-06-24 19:05 ` [TUHS] VFS prior to 1984 Paul Ruizendaal
2020-06-24 20:27 ` Derek Fawcus
2020-06-24 21:33 ` Greg A. Woods
2020-06-25 0:45 ` Adam Thornton
2020-06-25 19:40 ` Greg A. Woods
2020-06-23 22:17 Norman Wilson
2020-06-23 22:24 ` Dave Horsfall
2020-06-24 4:09 ` Warner Losh
2020-06-24 5:10 ` Dave Horsfall
2020-06-24 5:33 ` Bakul Shah
2020-06-24 9:10 ` Andrew Warkentin
2020-06-24 14:31 Noel Chiappa
2020-06-24 15:21 ` Clem Cole
2020-06-24 17:51 Noel Chiappa
2020-06-24 18:13 ` Richard Salz
2020-06-24 18:46 ` Lars Brinkhoff
2020-06-24 18:31 Norman Wilson
2020-06-25 6:22 ` arnold
2020-06-25 19:31 Noel Chiappa
2020-06-25 20:23 Noel Chiappa
2020-06-25 20:25 Noel Chiappa
2020-06-26 5:49 ` Lars Brinkhoff
2020-06-26 8:34 ` Dave Horsfall
2020-06-26 11:13 ` arnold
2020-06-29 9:11 Paul Ruizendaal
2020-06-29 14:45 ` Larry McVoy
2020-06-29 14:53 ` Paul Ruizendaal
2020-06-29 15:14 ` Larry McVoy
2020-06-29 16:34 ` Heinz Lycklama
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