I had a couple of servers unable to mount a NFS share at boot time. My
/etc/fstab was something like:
[... usual stuff ...] nfs.domain.tld:/nfs /nfs nfs4 _netdev,auto,rw,noexec,nodev,timeo=5,retry=5,retrans=5,rsize=32768,wsize=32768,proto=tcp,hard,intr 1 2
If I tried to mount it after boot, it would work without any problem.
After checking the basic stuff (services, network access, etc), I went to see if The Internet[tm] knew any better, and this suggestion was spot-on, for some reason that I couldn’t pinpoint, even if the mountpoint definition had a
_netdev attribute, it seemed like the mount was failing to properly resolve the name during the boot.
For the moment I went for a quick workaround, there was two main options: either add the NFS server hostname to
/etc/hosts, or switch to the IP address in
/etc/fstab. I went for the latter because it’s simpler (less stuff can break), until I can find out why it doesn’t resolve the names during the boot.