panic again

[Arne Wörner]

> Why  the  file  system  cannot  be  repaired  on  the  fly?  Is it the
> filesystem limitation? Why, say, NTFS can repair itself without a blue
> screen or a disk check?
>
I have found some reports about NTFS to be buggy, too, when I searched for
'+"turn off write cache" +ide +ata'...
I think a fault free source code, that solves a problem like a file system, is
quite difficult to produce, especially if someone chose not so common
parameters...
But I like the idea to track bugs down, where it seems to be reasonable (in
some cases, if the source code looks too funny, it would not make so much
sense, I think).

I cannot really complain about FFS with soft-updates. I observed once, that
after a halt with ACPI power-down _and_ with sync (as far as I recall it
correctly) my file systems were un-clean (during the reboot the kernel
panic'ed, because it felt something (a buf) was already free (as far as I can
recall it)). But I was able to fix it by some fsck's in single user mode. Maybe
I should mention, that I use three filesystems (root: 500MB, usr: 32GB, opt:
118GB) since several months and not so high avg. disc load (but with some peaks
and concurrency) under FreeBSD 5.2-CURRENT-20040408.

I think my problem with ACPI power-down happened due to this write cache thing
(or is ACPI to wait for the cache flushing? Maybe I pressed the power or reset
button... I do not know)?

At least I turned off hw.ata.wc (by setting it to zero) today. Now it feels
like writing from /dev/zero to a FFS device takes 5-6 times longer, but it
feels safer, too...

Does somebody know, if FFS works fine with modern hard discs (I do not know,
but I could think of a little energy-buffer, that powers the drive until the
cache is clean)?

Is there a way to make this 2 minutes time window for meta data updates smaller
(maybe 10 seconds or so)?

I would be glad, if somebody could tell me, how to provoke a ffs-related panic,
without choosing funny fs-parameters. Maybe then I could find a way to repeat
the problem. Btw.: I cannot enlarge my filesystems...

> BTW,  newfs  -g  375000  -h  8000  and  mkdir dir1 after that on newly
> created partition can cause panic as well :)
> 
> -- 
> / Pavel Merdine
> 
> 
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