Re: NFSv4

From: Trond Myklebust
Date: Fri Feb 19 2010 - 14:19:26 EST


On Fri, 2010-02-19 at 01:23 +0100, J.A. MagallÃn wrote:
> Hi all...
>
> First of all, kudos for new nfs-utils. Now, nfs4 works automagically and
> like a charm.
>
> And now the hard part, some questions:
>
> - I have read that nfs4 includes in the server the locking protocol, no
> need for separate lockd. But in my servers, it seems it is still running:
>
> root 2198 2 0 Feb18 ? 00:00:00 [nfsiod]
> root 23501 2 0 01:01 ? 00:00:00 [nfsd4]
> root 23502 2 0 01:01 ? 00:00:00 [nfsd]
> root 23503 2 0 01:01 ? 00:00:00 [nfsd]
> root 23504 2 0 01:01 ? 00:00:00 [nfsd]
> root 23505 2 0 01:01 ? 00:00:00 [nfsd]
> root 23506 2 0 01:01 ? 00:00:00 [nfsd]
> root 23507 2 0 01:01 ? 00:00:00 [nfsd]
> root 23508 2 0 01:01 ? 00:00:00 [nfsd]
> root 23509 2 0 01:01 ? 00:00:00 [nfsd]
> root 23500 2 0 01:01 ? 00:00:00 [lockd]
>
> Is there any problem with it ? I suppose (correct me if I'm wrong)
> that this kernel lockd will only serve for v2 or v3 mounts,
> that locking for client nfs4 mounts will go through nfsd4.
> Is that right ?

No. The client NFSv4 traffic goes through the ordinary 'nfsd' daemons.
There is no special locking manager for NFSv4, since POSIX locks are
part of the ordinary protocol.

I don't think that the NFS server will switch off lockd even if you do
specify that you only want to serve NFSv4.

> - Why is there only 1 instance of v4 daemon ?

The 'nfsd4' thread above is actually a workqueue that is used for
garbage-cleaning expired NFSv4 state. It isn't a server thread.

> - Is there any page describing the advantages of v4 ? I will have to
> convince the department admin to activate v4 in his solaris boxen...;)

One place to start is the NFSv4 design considerations. See
http://tools.ietf.org/html/rfc2624

Cheers
Trond

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