All the servers have the same /etc/resolv.conf file:
search our.domain.com
options ndots:2
nameserver ns0IP
nameserver ns1IP
I can't see any errors on the web servers or nfs servers referring a host lookup failure.
Thanks
Simone
On 8/15/07, Andreas Rogge <arogge@xxxxxx> wrote:
Hi Simone,
what nameservers are configured for the nfs-servers?
Afaict the nfs-server does forward and reverse lookup the clients. So if
your nfs-server's DNS breaks (i.e. if only ns0 is configured there and
you shut down ns0) you might see the issue you described.
Regards,
Andreas
Simone schrieb:
> Hi all,
>
> Today we have had a strange problem that has taken down our website, we
> understand what happened but not why so I am hoping someone has seen
> this before.
>
> We have our web servers (web1 web2 web3 ..... web10) mounting an NFS
> share (/export/data) from server nfs1. On the web server side we use
> autofs in the format nfs-dedicated:/export/data where nfs-dedicated is
> an alias in our internal DNS servers pointing to server nfs1. We run a
> primary and a secondary DNS (bind) server ns0, ns1 authoritative for our
> zones and our webservers have them configured in /etc/resolv.conf
> Today we had to run some upgrade on the dns servers (bios firmwares etc)
> so we took down ns0 and with it our website went down.
> All the nfs shares disappeared from the web servers (the logs show
> requests to mount/unmount timing out), but at the same time on nfs1 the
> logs show requests (mount and unmount) coming from the web servers and
> no errors.
>
> As soon as ns0 is back up, all gets back to normal. Minutes later we
> take down ns1 for maintenance and it doesn't have any impact on the
> website.
>
> dig @ns0 nfs-web gives exactly the same results on ns0/1
>
> Back to the office we try to reproduce the same scenario configuring
> iptables on web3 to block traffic to ns0 but the server (web3) keeps
> working fine reverting to ns1 for name resolution (as you would expect).
>
> Has anybody seen this happening before? Any comment/suggestion much
> appreciated.
>
> Thanks
>
> Simone
>
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