Digital Unix 4.0 oracle export prob..

Has anyone seen this before:
--clip--
About to export the entire database ...
. exporting tablespace definitions
. exporting profiles
. exporting user definitions
. exporting roles

EXP-00002: error in writing to export file EXP-00222:
System error message 14
EXP-00000: Export terminated unsuccessfully --clap--
this happens on digital unix 4.0d with recent patch set and exp is trying to write directyly /dev/nrmt0h (which is a dat tape).

If I boot the box, this works for a month or something like that, after uptime exceeds 30 days (or so) this begins happening.

Any ideas? This is propably something not oracle-specific, instead an OS problem? I've been trying to read the docs and grep /usr/include/* with no clues about what might be going on..

-- 
Antti Järvinen, costello_at_iki.fi
            "concerto for two faggots and orchestra"