Re: The next step: nfsvers=4

[Kevin Constantine <Kevin.Constantine-FfNkGbSheRGpB8w63BLUukEOCMrvLtNR@public.gmane.org>]

Steve Dickson wrote:
> Chuck Lever wrote:
>> If no vers= is specified and only NFSv4 is available on the server, but
>> something like "nocto" shows up on the command line mount options, do we:
>>
>> a) fail the mount, or
>> b) ignore the nocto option
> I would say ignore this particular option... since, in a sense, v4 give you this option
> by default due to delegations... but point well taken... The mapping of
> v3 to v4 and visa versa will have to be addressed... I would guess in the mount
> command...  
>  
>> a) seems like the least surprising behavior.
>>
>> What about "proto=udp" ?  Linux supports UDP for NFSv4, though other
>> server implementations probably don't.  If that's specified on a mount
>> command line without a vers= option, what version should we choose?
> I think people just want things to work... so if they specify only UDP
> and the server supports V4, we give them V4/TCP. If they REALLY want 
> UDP, they would have to specify 'nfsvers=3,udp'.
> 
> Or, if there was an mount configuration file, they could specify the
> MAX_VERSION to be 3 and then -o udp mounts work as expected...
> 

I would agree that things should just work as much as possible.  I would 
think that the options that aren't applicable should be ignored, and the 
  values that are known to be incorrect should be fixed if possible. 
More likely than not, I care that my mount succeeds.  Once that happens, 
I begin to care how it succeeded, and can go figure out where I made a 
mistake and how I ended up with v4/tcp when I really wanted udp and 
didn't care which nfs version I use.

>>> For implementing more complex policies, maybe we can extend
>>> the command syntax to accept a range and/or an ordered list
>>> of versions to try.
>> Steve mentioned /etc/default/nfs on Solaris.  I could see
>> /etc/sysconfig/nfs on Linux containing a couple of lines defining the
>> range of allowable NFS versions, if we think this is necessary.  This is
>> a simple pre-existing file, and has little potential for introducing
>> negative side-effects.

I like the idea of having a file that allows me to specify or default 
values, or acceptable ranges for the various mount options.  I'd also 
like to be able to specify overrideable options in the automount maps 
where the right-most option wins.

-kevin

> The /etc/sysconfig/nfs is a distro only file... Meaning I know of only 
> one distro that uses that file.. So I would tend to shy away from putting
> anything in that... 
> 
> steved.
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