[TUHS] shutdown for pre-v7 unix

Milo Velimirovic milov at cs.uwlax.edu
Fri Jul 18 12:58:00 AEST 2014


Three <mumble> for the Elven-kings under the sky,

On Jul 17, 2014, at 9:52 PM, Tim Newsham wrote:

> 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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