I am running on NetBSD 5 stable (from less than 30 days ago) on i386,
and

coda-6.9.5nb4       Coda distributed fileystem
rpc2-2.10nb1        CMU (Coda) remote procedure call package
lwp-2.6             Light Weight Process style threads
rvm-1.17            Recoverable Virtual Memory

From pkgsrc.  I have about 1G of files in my coda homedir; 848
directories and 4631 files.  du -s reports 1113464 blocks (1K); tar cf -
. reports 1087.7 MB, and my venus cachesize is 2000000. codacon reports
no fetches when reading it all, so I should not be having cache
evictions.  On one machine, I use bup to back them up, using bup pretty
normally (index, save).  This worked well for quite a long time.

Then, I started getting complaints about not being able to open "..".

I found that I had some directories that had about 53 files in them,
basically all 10 KB.  Sure enough, "ls -af" would show "..", but "ls -l"
would print instead a "..: not found" line.

I am able to 'cfs purge' the directory, and then things are ok.  But, I
find that multiple directories of the form

  FOO/BAR/2008 (through 2012)

all get their .. entries (should be the same directory) in this bad
state at once.

I am now having trouble reproducing this.  I wonder if bup's multiple
threads reading in parallel are the source of the trouble, but bup index
isn't provoking it either.

Has anyone else seen this?