"I'm out running around" (nfs problem)

[Jay Lessert]

In article <8772 at brazos.Rice.edu> Scott Todd writes:
>
>I had a truely annoying problem earlier today, Files in my network were
>being temporarly replaced with files of the right length and date/time.
>These files were filled with the string "I'm out running around", and were
>padded to length with nulls.

Bugid 1026933, "NFS Confused File".  Exists in SunOS 4.0.x and 4.1.

As of about a month ago, the bug and appropriate fixes were very well
understood by Sun.  A fully-QA'ed production patch for 4.0.3 is currently
scheduled to be released in July.  The same for 4.1 should be available
much sooner (maybe even now), since there are fewer (or no) other NFS
patches to be compatible with...

Grossly oversimplified (all my feeble brain is capable of understanding),
the problem is that an NFS client can become confused about whether a
given linked list of vmpages is allocated or not, and to which file.  So
the system literally reads a vmpage, thinking it contains "file1" already
in memory, when in fact that vmpage has more recently been used to write
"file2".  Oops.  Nothing wrong with the *real* contents of the file (on
disk on the server).  Our experience is that the best thing to do is
immediately reboot the client.

One thing for sure is that your NFS client has an application program that
writes the string "I'm out running around" to a file.  This application
may or may not contribute to triggering the bug.  In the hardware
configuration you mention (mostly SS1's with a single 4/390 server) there
is probably nothing you can do to prevent the bug from occurring.

Jay Lessert  {ogicse,sun,decwrl}!bit!jayl
Bipolar Integrated Technology, Inc.
503-629-5490  (fax)503-690-1498