NFS-client does not shutdown when NFS-server is offline

[Lomaxx]

I have two Gentoo-computers in a local network. One is the NFS-Server. The other is a NFS-client which is configured to use the NFS-mounts via autofs or manually via the 'mount'-command (an fstab-entry exists) for ordinary datastorage-transfer (i.e storing/accessing music and movies). Everything works fine, except for the fact, that in certain cases the client hangs on shutdown, when i turned off the server before.

The reason for this, is that the client keeps trying to reach the NFS-server in order to unmount the shared directories. I experimented a little bit and noticed two different points, where the computer freezes on shutdown:


Situation 1:
If i manually mount the the share by using 'mount /mnt/client_storage', later forget to unmount the share, then turn off the server and afterwards try to shut down the client, then the shutdown-process halts rather early. fstab-entry looks like this:

server:/mnt/storage /mnt/server_storage nfs rw,_netdev,user,noatime,noauto,nfsvers=3 0 0

This means i must not forget to unmount the shares before shutting down the server in order to make the client shutdown correctly

Situation 2:
I am getting the same result if i use autofs to mount the shares and shutdown the server before autofs unmounts the share. I helped myself by setting the time-out-value of autofs for unmounting not used mounts to "1" (second). This way i only have to remember to close all applications and terminals that access the shared directories before shutting down the server.

Situation 3:
However i still ran into problems when using autofs after it unmounted the shares. The shutdown-process then halts later than in situation 1 and 2. Not while the NFS-script is stopping, but later on when unmounting drives. I managed to get arround this by replacing the "hard"-parameter with the 'soft'-parameter in /etc/autofs/auto.net.

Anyway after all this confusion: What i would like to have is a setup, where the NFS-server on shutdown would send a signal to the client saying "hey you are still using some of my shares. please unmount all shares." and halts until all clients do so. Additionally the client should determine if it gently could unmount the drives when there is no write-access going on, but only a terminal is still left open that is accessing a shared-directory. Is something like this possible with NFS? Or should i switch to alternatives like 'sshmount'. Which is the best setup for a home-network for sharing media from one computer to another?

Lomaxx

[fangorn]

As NFS is designed as a stateless connection AFAIK (aka. expect the server running and serving all the time), NFS client is waiting till the server is up again. You can adjust timeouts for error messages, so your client won't hang forever waiting on response, but you cannot advise NFS server or client to acknoledge a server shutdown.

It is a big No-No shutting down a server before the last client exits!!!!
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[Lomaxx]

Thanks for your answer fangorn.

So what would be a better solution? sshmounts? ftpmounts? something else? Which are the user-friendliest with nice performance and options?

[kimmie]

You're probably best off using samba on the server and cifs mounts on the gentoo client. Then you'll be able to connect windows clients too (pesky things, they keep popping up).

[pappy_mcfae]

Samba is a good thing. However, if you decide to go that route, steer clear of smb4k. It is a computer killer. Well, not a killer, but it nuked a dozen icons and their directory for no good reason. If you think you have trouble with NFS, it's a picnic compared to what smb4k can do.

You can create scripts to mount and unmount the desired shares, and you can do it with Windoze boxes or Llinux boxes. Doing it that way is infinitely more fault tolerant. It won't completely eliminate the problem. but it will make it better.

The best idea is still turning off the client machine first. I always make sure I shut down the laptops before the server. That way, problems averted.

Blessed be!
Pappy
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[drescherjm]