Re: [pnfs] [RFC 0/4] nfs-utils: nfsd support for minor version

[Benny Halevy <bhalevy@panasas.com>]

On Apr. 17, 2009, 19:18 +0300, Chuck Lever <chuck.lever@oracle.com> wrote:
> On Apr 17, 2009, at 8:35 AM, Steve Dickson wrote:
>> J. Bruce Fields wrote:
>>> On Thu, Apr 16, 2009 at 03:01:47PM -0400, Steve Dickson wrote:
>>>> I do get your point, but as we did with the initial v4 support,
>>>> having the support on by default and then having away to turn it
>>>> off is the correct approach... IMHO...
>>> I'd prefer it be off by default, for the obvious safety reasons.   
>>> (It's
>>> under rapid development and particularly likely to have bugs).  The  
>>> only
>>> reason we had it on by default before was that we didn't add the
>>> switching mechanism early enough.  (Well, and because we could keep  
>>> it
>>> off in the config.  But I'd rather be able to ship users a kernel  
>>> that
>>> supports 4.1 and give them the option of turning it on at runtime,  
>>> than
>>> make them build a new kernel.)
>> I agree with not making people recompile kernels, which is the whole
>> purpose behind the Fedora repos, but do I think you might be a bit
>> too cautious with exposing the technology.
>>
>> One, I've been running the kernels with everything enabled for a while
>> now with no problems whatsoever... A few scary looking warnings now  
>> and
>> then but nothing major. I also spent the majority of my time at  
>> Connectathon
>> this years testing with kernel that were fully enabled. Not one  
>> problem
>> WRT regression testing. Plus there is no better way to expose  
>> regression
>> problems (early on) than to enable the code.. IMHO...
>>
>> Second, its my understanding that clients have to explicitly  ask
>> for 4.1 support. Are there any client out there that default to
>> 4.1 support? I would think not since there is only one client out  
>> there
>> that defaults to V4.0. If there is a client that defaults to 4.1,  
>> then we
>> will a knob to turn that support off.
> 
> That might even be OK for Fedora-based NFS servers.  I think what you  
> are driving at is erring on the side of increasing the testing base.
> 
> For an enterprise distribution, however, I suggest following the  
> experience of proprietary storage vendors who enabled their NFSv4.0  
> implementation early, and were bitten hard by that decision.  They are  
> still dealing with the bad press.
> 
> 4.1 support should be left turned off by default, or disabled  
> entirely, in enterprise distributions until we have a high degree of  
> confidence that 4.1 doesn't open security or data integrity exposures,  
> and that the feature set is stable.  Perhaps you could provide a  
> "technology preview" release of RHEL 6 with NFSv4.1 enabled, just as  
> was done with FScache in earlier RHEL releases?

That sounds like a good compromise to me.

Benny

> 
> --
> Chuck Lever
> chuck[dot]lever[at]oracle[dot]com
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