Subject: Re: Design of NLM

From: "Koundinya" <[email-masked]>
Date: Wed, 08 Jan 2003 15:08:51 +0000

--------
Hi,
	Thanks a lot. I just got a copy of your book purchased and it's 
really informative. I have been doing some reading on NFS to 
study NFS implementations for various NAS Boxes available in the 
market today and the issues surrounding them in areas of 
locking. I have some doubts, which if you can clarify would be 
helpful to me:

One some UNIX Flavors like Tru64, IRIX etc there seems to be no 
lockd or statd and I suppose that tells that they do not have 
the Lock Manager or Status Monitor Protocol implemented. While 
on Solaris I do see these. In case these protocols are not 
implemented, then how is locking achieved and what type of 
locking probably they would follow.

For NAS boxes most often not much is spoken about the NFS 
implementation. Do you have any idea as to how they would be 
handling the locking issues ?.

Thanks for any information.

Koundinya

P.S: Please mark a copy of this mail to my e-mail id also. 

>>>>> On Mon, 23 Dec 2002, "Brent" == Brent Callaghan wrote:

  Brent> Take a look at Chapter 10 of "NFS Illustrated".  It
  Brent> describes the NLM protocol and illustrates its use.

  Brent> Brent

  Brent> Koundinya wrote:

  +> Hi all, I have been making a comparison study of locking in
  +> NFS. I have gone through several archives in the mailing
  +> list.I have also browsed through the specifications of the
  +> NFS v4 but there's not too much given about the NLM. Where
  +> can I find a good description of this.

  +> Thanks for any information.

  +> Koundinya

---

From: Guy Harris <[email-masked]>
Date: Wed, 8 Jan 2003 11:29:36 -0800

On Wed, Jan 08, 2003 at 03:08:51PM +0000, Koundinya wrote:
> the Lock Manager or Status Monitor Protocol implemented.

No, the only thing that will tell you that would be a command such as
"rpcinfo" - run "rpcinfo -p" on the Tru64 or IRIX machine that has NFS
enabled, and see if it reports programs 100021 and 100024.  If it does,
they are implementing the lock manager and status monitor, even if they
don't happen to do it with "lockd" or "statd" programs.

> handling the locking issues ?.

Well, we handle the locking issues with processes that implement the
lock manager and status monitor protocols.  I suspect other NAS
appliance vendors do the same.

---

From: Eric Werme USG <[email-masked]>
Date: Thu, 09 Jan 2003 13:56:42 -0500

Not at all.  As Guy Harris mentioned, "rpcinfo -p" is authoritative,
though I prefer "rpcinfo -u" or "rpcinfo -t" because that actually
contacts the service by sending a NULL request.

In Tru64's case, we have supported locking since day one:

  $ ps ax | grep rpc
   485 ??       I        0:00.03 /usr/sbin/rpc.statd
   487 ??       I        0:00.07 /usr/sbin/rpc.lockd

Our sysadmin tools allow _not_ running them, so keep in mind that
rpcinfo will reports only that the service is currently available.
It has no way to check whether support has been implemented but is
not in use on a particular system.

Irix also supports locking.  In general, any credible UNIX NFS
implementation has locking, and any NFS toaster sold in the Unix
market has locking.

 While 

There are some classic (and mostly deprecated) locking forms, but
they generally lock an entire file, don't work well over reboots,
and in general cause more problems than record locking does.

This is off-topic for the V4 mail list.  If you have other questions about
NFS in Tru64 Unix, please contact HP support or me directly.

	-Ric Werme