Dilip,
I completely agree with Bart on this one. the "broken pipe" is usually sinonymous with an interrupted, or, more plainly put, terminated process.
So, it looks like the process got interrupted, and there can be a number of reasons why this would have occurred.
I would just monitor, and if this happens again, then, research more deeply. In the meantime read up on SYMULTNUF processes.
If I recall, Backup Server spawns one SYMULTBUF process per stripe per DB... I have not looked at the internals since 2002, so, my information might be dated, but it will give you something to look into in the documentation.
Usually when there are SYMULTBUF errors, it means that you are running out of file descriptors at the OS level to start another process? There were two many concurrent dumps, or you were stripping too agressively.
My two cents.
Regards,
Jean-Pierre
P.S. Of course, paranoid me, could think somebody just did a kill -9 on the thread! LOL