Comment # 2 on bug 990356 from jc sl

(In reply to Neil Brown from comment #1)
> What exactly do you mean by "with RPC" ??
> RPC is the protocol that NFS uses.  Without the RPC protocol, there is no
> NFS.
> 

Bad title, right. What I want is to start only the mandatory
programs/services/daemons or whatever is needed by a NFSv4 only server.

> rpc.mountd is an intrinsic part of the NFS service, even for NFSv4.  If you
> disable NFSv3 service, then rpc.mountd shouldn't listen for mount requests,
> but it sill needs to be running.
> 

I'm not sure about this. I have read this in the CentOS and Red Hat
documentation:

- CentOS: rpc.mountd ��� ... This is not used with NFSv4. 
- Red Hat: The mounting and locking protocols have been incorporated into the
NFSv4 protocol. The rpc.mountd daemon is still required on the NFS server to
set up the exports, but is not involved in any over-the-wire operations. 

I don't understand the last part of the Red Hat's documentation paragraph. I
did read quite a bit about NFS some time ago, and IIRC I did setup a perfectly
working NFSv4 without rpc.mountd running on 13.2, but my memory is crap. If the
mount protocol has been incorporated into the NFSv4 the protocol, why should it
be needed at all?

> rpcbind is not technically necessary for NFSv4, however "systemctl disable
> rpcbind.socket" isn't sufficient to disable it.  I guess those release notes
> are wrong.
> 
>    systemctl mask rpcbind.socket
> 
> should stop rpcbind from running.  That, in turn, should stop rpc.statd from
> running, which is only needed for NFSv2 and NFSv3.

As I wrote in my report, if you mask rpcbind.socket the system doesn't boot. It
gets stuck in a probably infinite wait: "A start job is running for NFS server
and services (xxx / no limit)", with xxx being a timer. I did setup a virtual
machine to confirm this behaviour so I think that it is reproducible.

> rpc.idmapd, like rpc.mountd, is an intrinsic part of NFSv4 service.  It
> doesn't make sense to try to turn it off.

I agree with rpc.idmpad being mandatory, not sure about rpc.mountd however.


References:

-
https://www.centos.org/docs/5/html/5.2/Deployment_Guide/s2-nfs-how-daemons.html
-
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Storage_Administration_Guide/ch-nfs.html

Greetings.