I have to say I found it easier (marginally) to use the basic MRTG distribution and copy-in the useful bits from the NOW package - largely because it'd been prepared and tailored a leetle too much in NetApp 8)
I, for example, wanted/needed to run it all on an SGI box, and the precompiled SPARC binaries weren't very useful in this instance (read HP/IBM/Linux/etc. if more apt).
I'll have to do the same thing over again when I get the latest MIB.
I'd kill to get my hands on the proper SNMP tools where I work, as it is I have to work far too hard to work out what variables do what to get even basic info out of any MIB. But that's just a general complaint about SNMP on my part. 8)
MRTG is useful, but it's also very limited. I want to do some graphs which tie together the main characteristics of filer (network use, CPU, NVRAM-cache-flushes, cache-age, NFS-ops, CIFS-ops) on the same graphs - try to do that with just two variables. (Yes some of those are desirable but not currently reported - to the observant who spotted my imagination running away with my fingers).
I also wanted to be able to graph all the per-client stats. But the problem we found there was that the filer only kept a table of 256 such stats, or at least that's all the we could get through SNMP.
Per-volume, per-client stats, now that'd be interesting. Per-volume stats would be interesting. Per-disk stats, would be interesting, if slightly un-immediately-useful.
Exposing more of the error- and performance-reporting from the disks would be fascinating too. You could graph that data over time to see if there's a disk that's being hot-spotted for some reason, or which is throwing up more low-level, otherwise hidden errors, or which is responding in a below-par relative to its siblings. You could move data around or pre-emptively maintain problems with such information.
As the number of clients and disk increase, getting these stats might make the difference between running a silky-smooth operation with the filer or having disks blow randomly in quick succession in just the most critical sections of the filer, serving the most demanding clients - without even knowing such a relationship pertained.
That's my Xmas wishlist on the topic. I'll be praying Santa listens to this one though.