RE: [LDAP-interop] RedHat ES4 boot hangs mounting NFS filesystems

["Collins, Kevin (MindWorks)" <KCollins chevron com>]

Very interesting. I have seen other "odd" behavior when using LDAP on
ES3 - it basically would NOT work without nscd running (commands would
hang or seg fault).

I didn't have any bad cache entries because I had nscd running but
configured for no host cache and also because I tried your suggestion of
'nscd -i hosts'. The mount still hung.

However, when I changed nscd to have:

enable-cache            hosts           yes 

the mount then succeeded.

So, it solves my problem, but now I am having some serious concerns
about the Linux/LDAP combination. Why is it required that I run nscd in
order to use LDAP? Granted, it can give a performance enhancement, but
it shouldn't be a requirement...

Thanks,

Kevin

-----Original Message-----
From: dijuremo math gatech edu [mailto:dijuremo math gatech edu] 
Sent: Tuesday, July 12, 2005 11:46 AM
To: OpenLDAP interoperability list; Collins, Kevin (MindWorks)
Cc: nahant-list redhat com; ldap-interop fini net
Subject: Re: [LDAP-interop] RedHat ES4 boot hangs mounting NFS
filesystems

One thing to check is nscd.  The name service caching daemon. If you
have
nscd running and you do a query that fails once, when you keep doing the
query then it will keep failing without even trying to talk to the
server
again because the result to the query is cached.  This has happened to
me
before and you just need to clear the cache.

Clear the nscd cache as follows:

nscd -i passwd
nscd -i hosts
nscd -i group

HTH,

Diego

Quoting "Collins, Kevin (MindWorks)" <KCollins chevron com>:

> Hi,
>
> 	I converted a RedHat ES4 system to use LDAP (it was previously
> using NIS) yesterday. Now, when I attempt a boot, the system hangs at
> "Mounting NFS Filesystems" (part of the /etc/init.d/netfs rc script).
I
> have an ES3 system configured the same and it works fine.
>
> I have narrowed the problem down to using LDAP for hostname resolution
> in /etc/nsswitch.conf:
>
> hosts:      files ldap dns
>
> The NFS host (one server for all mounts in question) is in both LDAP
and
> DNS. If I attempt booting with this configuration the system hangs
> trying to mount NFS filesystems.
>
> Any of the following fix the problem:
>
> 1) add the host in question to /etc/hosts
> 2) put dns before ldap in nsswitch.conf
> 3) change /etc/fstab to use the IP address of the NFS server
>
> If I boot to runlevel 2 (before NFS mounts occur), I can login and run
> 'getent' successfully and it immediately returns the information from
> LDAP (I can tell because LDAP has aliases and DNS doesn't). If I then
> try an init to runlevel 3 or 5, it hangs at the NFS mount step.
>
> Does anyone have any ideas? I can't put DNS ahead of LDAP in the
search
> order because DNS is outside my group's control and we need to have
> changes available at near-realtime.
>
> I've carbon-copied the LDAP Interop list as well, hoping someone can
> help.
>
> Thanks,
>
> Kevin
>