Re: Questions about NFS over TCP

[James Pearson <james-p@moving-picture.com>]

Trond Myklebust wrote:
> 
> >>>>> " " == James Pearson <james-p@moving-picture.com> writes:
> 
>     >> The disadvantage of using TCP is that it is not a stateless
>     >> protocol like UDP. If your server crashes in the middle of a
>     >> packet transmission, the client will hang and any shares will
>     >> need to be unmounted and remounted.
> 
> This is not really true. If the connection is broken, the client
> should detect it, and automatically attempt to reconnect. It may be
> that there are still bugs (I hope not) but the machinery is already
> there.

Thanks for the info - do you know what the 'best' combination of (2.4.X)
kernel/patches gives the most stable NFS over TCP support?

> 
>      > What is the 'best' way to get mount to try an TCP mount first -
>      > if that fails, then try a UDP mount - I had a look at the mount
>      > source and hacked in something to do this if the options -o
>      > tcp,udp are given - my hack is very simple, if the TCP mount
>      > fails (for whatever reason), the try a UDP mount - however, I
>      > don't know how 'safe' this is ...
> 
> It should be fairly safe: after all this is what most NFS clients do
> anyway. I've had a patch available for quite some time on
> 
>   http://www.fys.uio.no/~trondmy/src/util-linux-2.11n.dif.gz
> 
> that makes this easy. Just go to the function 'proto_probelist()' and
> swap the order of UDP and TCP.

That seems to work fine ...

Thanks

James Pearson


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