zfs discuss - Oct 2012 - Trick to keeping NFS file references in kernel memory for Dtrace?

Hey all,

So I have a couple of storage boxes (NexentaCore & Illumian) and have 
been playing with some DTrace scripts to monitor NFS usage.  Initially I 
ran into the (seemingly common) problem of basically everything showing 
up as ''<Unknown>'', and then after some searching online
I found a
workaround was to do a ''find'' on the file system from the
remote end and
it would refresh the kernels knowledge of the files.  This works.. 
however it doesn''t stay for good.  It seems to sometimes last a couple 
of hours (and sometimes much less) and then we are back to receiving 
<Unknown>''s.

Has anyone else come across something similar?  Does anyone know what 
may be causing the kernel to lose the references?  There is plenty of 
memory in the main system (72gb with ARC sitting ~53gb and 11gb
''free''),
so I don''t think a OOM situation is causing it.


Otherwise does anyone have any other tips for monitoring usage?  I 
wonder how they have it all working in Fishworks gear as some of the 
analytics demos show you being able to drill down on through file 
activity in real time.


Any advice or suggestions greatly appreciated.

Cheers,
Mark