[Nottingham] NFSv3 - NFSv4 upgrade gotcha

[Martin]

For anyone upgrading from NFSv3 to NFSv4, three gotchas to watch out for NFSv4:

1: Name mapping is now used. As part of that, you need to set up
"/etc/idmapd.conf". The default in there uselessly has
'local.domain.edu' set as the default rather than 'localdomain'. You
need to fix that if you see things like:

rpc.idmapd[...]: nss_getpwnam: name 'root at localdomain' does not map
into domain 'local.domain.edu'


2: All hosts need to be resolvable for lookup. Easiest is just to list
them in the "/etc/hosts" file. An example /var/log/messages error is:

rpc.idmapd[...]: nss_getpwnam: name 'whatever-host-name' not found in
domain 'localdomain'

Or add them to your own local dns.


3: And that's all to allow NFS to now use name strings to identify
user and group ids and map them between hosts. However, if you don't
have all the usernames set in "/etc/passwd", then you'll get a whole
load of 'nobody'! Note that the uid and gid *numbers* no longer need
to match... Hence the mapping that's been introduced!


Don't forget to restart rpc.idmapd for any changes.


I think this one example where an update should give a good warning
and at least a pointer to a readme...

Cheers,
Martin