Odd network issues on ZFS based NFS server

[Gary Palmer]

On Thu, Jun 10, 2010 at 04:46:14AM -0700, Jeremy Chadwick wrote:
> Clarification: I believe it actually has 1927MB (147M Inact + 1780M
> Free) available.  I've always understood top's "Free" field to mean
> "number/amount of pages which have never been touched/used since the
> kernel was started", while "Inact" to mean "number/amount of pages which
> have been touched/used but are not actively being used, this available
> for use".
> 
> If someone more familiar with the VM and top could expand on this,
> that'd be helpful.

I'm not a VM guru, however here is my understanding:

- "Free" are pages that have been reclaimed by the page daemon and are
  ready for immediate use without further action.  The page daemon always
  tries to keep a few pages in the "Free" state to avoid problems with
  page starvation

- "Inactive" pages are pages that are candidates for reclamation by the
  page daemon if so needed.  I believe some amount of work is needed to
  move an inactive page to the free list, including zeroing it I think as
  well as removing any references still pointing to it (e.g. it could be
  a cached copy of data from local storage).  

Probably not completely 100% accurate as I haven't kept up with VM changes
in the last few years, but close enough for government work :)

Regards,

Gary