The first script fails because the example is incorrect. You can't reference
args while globbing the probe in that manner (as probes matching the pattern may come and go while the enabling is still in effect, so guarantees about the type of
args[N] can't be made). You'd need to list each
nfs3-op-* individually, comma separated
nfs3:::op-read-start,nfs3:::op-write-start etc, for each operation you care about.
nfsv3fileio.d the Rbytes and Wbytes of "unknown" are very large, because they're the sum of all I/O to unknown paths (probably several, perhaps many).
The paths are
<unknown> because the kernel only stores path information in the vnode lazily (if it happens to be present, it's stored, but it's not actively sought out). And as such is not always available. There are tricks that sometimes force it into place (I seem to recall that
find across the FS in question should do it, but my memory could be playing tricks).