Date: Tue, 23 Feb 1999 08:22:47 +0000 From: Brian Somers <brian@Awfulhak.org> To: tom@tomqnx.com (Tom Torrance at home) Cc: hackers@FreeBSD.ORG, current@FreeBSD.ORG Subject: Re: Missing files/directories Message-ID: <199902230822.IAA00707@keep.lan.Awfulhak.org> In-Reply-To: Your message of "Mon, 22 Feb 1999 21:56:49 EST." <m10F81h-000I1oC@TomQNX.tomqnx.com>
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Hi,
I don't claim to know a great deal about cache code etc, but I'm
pretty sure that it's extremely unlikely that the file name has any
chance of affecting the buffer cache. While NFS has its fair
share of problems (with which Matt is dealing with admirably), I
would think that the code that does the work there is equally unlikely
to know anything about file names.
Having said all that in as vague a way as possible, the reason I'm
posting this is that you seem to be experiencing difficulties with
ppp that are of a similar nature - that is, completely inexplicable
and unseen by anyone else - disappearing default routes, ppp.linkdown
not being processed,
I'm beginning to suspect a hardware problem - perhaps with your disk
controller or something. This wouldn't easily explain the default
route problem, but may explain the failure to process ppp.linkdown....
Maybe you could try treating the other machine (your son's machine?)
as the gateway, and see if things become more stable. If they do,
the finger might be pointed more firmly at hardware.
> On the weekend I reported to hackers about problems experienced with
> 2.2-stable and RELENG-3 systems where I experienced files that
> disappeared from cache and Mail directories that disappeared.
> The RELENG-3 system had files affected with softupdates enabled.
> The 2.2-stable system had sub-directories missing from the
> same directories that I was writing to via nfsv2.
>
> By coincidence, I had cvsup'd and compiled new kernels and naturally
> made the assumption that there was causality there. Subsequently
> I have come to believe that the problem may have more to do with what
> I was doing, not changes to the code.
>
> For about 3-4 hours prior to noticing the problems, I had been
> repetitively editing dot files, then writing a kludge of dot files
> to the local system hard drive and to the nfs exported FS of the
> other computer, while occasionally checking mail on that computer.
>
> All files and directories missing were being updated for
> one reason or another by myself or by mail processes while
> I was doing this.
>
> It is speculation, but there is a good chance that there is a bug
> in the cache-handling code that causes problems with other files
> or directories being dropped from cache because of bad processing
> common to BOTH or ALL releases, when large numbers of dot files are
> being written. The dot files themselves did not disappear - other
> items to be written disappeared before their writes actually
> occurred.
>
> I know that this is a frustrating kind of message to receive, but
> I am not a developer & not qualified to go into the code myself.
> Also no logs or hard output are available - files/directories
> simply disappeared without any error messages.
>
> I just did a scan of the entire /usr/src/sys tree for \"\\.\"
> and \'\\.\' to see what code sections might be affected - mostly
> cache-handling. In quantity, not bad, really.
>
> Others have apparently reported missing files to do with nfs
> I believe. THis might or might not be a related problem.
>
> I guess that I am asking someone who is qualified, and concerned
> about missing files or directories, if they would be willing
> to do what I cannot - check the code for bad interactions when
> dot files are being written- bearing in mind that it is OTHER
> files/directories that are disappearing from cache before being
> written.
>
> Is anyone out there sufficiently intrigued by the possibility
> to invest some valuable time?
>
> I am a QA tester, not a developer, and therefore much more
> comfortable with discussion of symptoms and speculative
> causality than most developers I have known. I hope that
> someone thinks enough of the possibility to invest some
> time, which I know is in very short supply. I cannot deny
> that this is (informed) speculation - there are no guarantees.
>
> Regards and best wishes,
> Tom
--
Brian <brian@Awfulhak.org> <brian@FreeBSD.org> <brian@OpenBSD.org>
<http://www.Awfulhak.org>;
Don't _EVER_ lose your sense of humour !
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