[TUHS] shutdown for pre-v7 unix

Tim Newsham tim.newsham at gmail.com
Fri Jul 18 12:52:01 AEST 2014

One sync for the disks and two for the operator's peace of mind...

On Thu, Jul 17, 2014 at 4:26 PM, Ronald Natalie <ron at ronnatalie.com> wrote:
> On Jul 17, 2014, at 4:16 PM, Clem Cole <clemc at ccc.com> wrote:
> I think that's is a problem in that it needs to be data blocks, inodes, and
> finally superblocks to do the least damage in a crash.
> That is definitely the case and that was perhaps the biggest fix in BSD (and
> other later) was to make the file system writing more consistent so at least
> you didn't get trashed filesystems but at worst got some orphaned blocks
> that needed intervention to reclaim.
> It was mandatory for operators at JHU to understand how the file system was
> laid out on disk, and what icheck/dcheck reported and what the options to
> fix things.   Link counts that were too low and dups in free should NEVER
> happen with an intelligently ordered set of I/O operations, but thats not
> what Version 6 UNIX had.   It wasn't uncommon to find several errors in the
> file system that would be degenerate system faults if not corrected.
> But all that aside, even in those shakey days, typing sync multiple times
> really didn't accomplish anything and it because less useful as the file
> systems became more stable.
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Tim Newsham | www.thenewsh.com/~newsham | @newshtwit | thenewsh.blogspot.com

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