Re: [9fans] boot error walking

[Charles Forsyth <forsyth@terzarima.net>]

>>effects, recovery is comprehensible and complete, and finally improper
>>operation (e.g.  letting the disk fill up) should not result in an
>>unbootable machine.  ... it has a long way to go to equal
>>what I'm used to in the Unix/Linux world.

i must be imagining that my Linux partition is currently unbootable
because it filled up and resulted in an unbootable partition.
oh all right, i can boot it but it can't start up properly.
fortunately, i can still boot the machine with something else.
still, i remember that you were also lucky with IBM's AIX/JFS recovery,
which they appear to have debugged some time after i used it!
i'm generally fairly lucky myself, but not those times.

>>I keep wondering if the kinds of
>>guarantees on I/O ordering that a file system needs for its activities can
>>be met outside a kernel? ..

i'm not sure i see why not.
for instance it could write "keep off" into a ctl file to stop
re-ordering (not that i think the kernel does),
or to get the sd*.c to signal the drive to stop re-ordering.
fossil itself was supposed to fuss quite a bit in the soft update
style to get the resulting order right (if the drive doesn't muck it up).

i'm currently a bit less worried about crash on power failure/off than
i am about software bugs, and i had the impression we had some of
the latter in at least one of fossil or venti.
(i'd prefer it to be venti because it's logically simpler, but i did find
and fix something in fossil before.  admittedly it was along the lines
of a statement that could have had a comment ``yes, the bug is here''
because it stood out so much, so that was easy.)