I'm running a small server for our flat share. It's mostly a file server with some additional services. The clients are Linux machines (mostly Ubuntu, but some others Distros too) and some Mac(-Book)s in between (but they're not important for the question). The server is running Ubuntu 11.10 (Oneiric Ocelot) 'Server Edition', the system from which I do my setup and testing runs the 11.10 'Desktop Edition'. We where running our shares with Samba (which we are more familiar with) for quite some time but then migrate to NFS (because we don't have any Windows users in the LAN and want to try it out) and so far everything works fine.

Now I want to setup auto-mounting with autofs to smooth things up (up to now everyone mounts the shares manually when needed). The auto-mounting seems to work too. The problem is that our "server" don't run 24/7 to save energy (if someone needs stuff from the server s/he powers it on and shuts it down afterwards, so it only runs a couple of hours each day). But since the autofs setup the clients hang up quit often when the server isn't running.

• I can start all clients just fine, even when the server isn't running.

• But when I want to display a directory (in terminal or nautilus), that contains symbolic links to a share under /nfs while the server isn't running, it hangs for at least two minutes (because autofs can't connect to the server but keeps trying, I assume).

  • Is there a way to avoid that? So that the mounting would be delayed untill a change into the directory or till content of that directory is accessed? Not when "looking" at a link to a share under /nfs? I think not, but maybe it is possible not to try to access it for so long? And just give me an empty directory or a "can't find / connect to that dir" or something like that.

• When the server is running, everything works fine.

• But when the server gets shut down, before a share got unmounted, tools (like df or ll) hang (assuming because they think the share is still on but the server won't respond anymore).

  • Is there a way to unmount shares automatically, when the connection gets lost?

• Also the clients won't shutdown or restart when the server is down and they have still shares mounted. They hang (infinitely as it seems) in "killing remaining processes" and nothing seems to happen.

I think it all comes down to neat timeout values for mounting and unmounting. And maybe to remove all shares when the connection to the server gets lost.

So my question is: How to handle this? And as a bonus: is there a good way to link inside /nfs without the need to mount the real shares (an autofs option or maybe using a pseudo FS for /nfs which gets replaced when the mount happens or something like that)?

My Setup

The NFS setting is pretty basic but served us well so far (using NFSv4):

/etc/default/nfs-common

NEED_STATD=
STATDOPTS=
NEED_IDMAPD=YES
NEED_GSSD=

/etc/idmapd.conf

[General]
Verbosity = 0
Pipefs-Directory = /var/lib/nfs/rpc_pipefs
Domain = localdomain
[Mapping]
Nobody-User = nobody
Nobody-Group = nogroup

/etc/exports

/srv/   192.168.0.0/24(rw,no_root_squash,no_subtree_check,crossmnt,fsid=0)

Under the export root /srv we got two directories with bind:

/etc/fstab (Server)

...
/shared/shared/      /srv/shared/      none    bind  0 0
/home/Upload/        /srv/upload/      none    bind  0 0

The 1st one is mostly read only (but I enforce that through file attributes and ownership instead of NFS settings) and the 2nd is rw for all. Note: They have no extra entries in /etc/exports, mounting them separately works though.

On the client side they get setup in /etc/fstab and mounted manually as needed (morton is the name of the server and it resolves fine).

/etc/fstab (Client)

morton:/shared  /nfs/shared nfs4    noauto,users,noatime,soft,intr,rsize=8192,wsize=8192    0   0
morton:/upload  /nfs/upload nfs4    noauto,users,noatime,soft,intr,rsize=8192,wsize=8192    0   0

For the autofs setup I removed the entries from /etc/fstab on the clients and set the rest up like this:

/etc/auto.master

/nfs    /etc/auto.nfs

First I tied the supplied executable /etc/auto.net (you can take a look at it here) but it won't automatically mount anything for me. Then I write a /etc/auto.nfs based on some HowTos I found online:

/etc/auto.nfs

shared  -fstype=nfs4  morton:/shared
upload  -fstype=nfs4  morton:/upload

And it kinda works… Or would work if the server would run 24/7. So we get the hangups when a client boots without the server running or when the server goes down while shares where still connected.