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On Mar 20, 2012, at 9:29 AM, Nikolaus Rath <Nikolaus@xxxxxxxx> wrote:
> On 03/19/2012 06:25 PM, Rick Macklem wrote:
>> Nikolaus Rath wrote:
>>> On 03/19/2012 02:39 PM, J. Bruce Fields wrote:
>>>> On Mon, Mar 19, 2012 at 02:29:46PM -0400, Chuck Lever wrote:
>>>>>
>>>>> On Mar 19, 2012, at 2:27 PM, J. Bruce Fields wrote:
>>>>>
>>>>>> On Mon, Mar 19, 2012 at 01:47:14PM -0400, Chuck Lever wrote:
>>>>>>>
>>>>>>> On Mar 19, 2012, at 1:36 PM, J. Bruce Fields wrote:
>>>>>>>> Well, sure, but all I'm proposing here is returning
>>>>>>>> NFS4ERR_INUSE in the
>>>>>>>> case where we get setclientid's with the same client-provided
>>>>>>>> id.
>>>>>>>> There'd be no change of behavior in the case of multiple clients
>>>>>>>> sharing
>>>>>>>> an IP (which is fine, of course).
>>>>>>>
>>>>>>> The migration draft proposes that clients use the same
>>>>>>> nfs_client_id4 string for all of a server's IP addresses. Would a
>>>>>>> server then be obliged to return NFS4ERR_CLID_IN_USE if a client
>>>>>>> attempts a SETCLIENTID with the same boot verifier and
>>>>>>> nfs_client_id4 on more than one IP address for the same server?
>>>>>>
>>>>>> That's also not this case, sorry, this time with all the
>>>>>> conditions:
>>>>>>
>>>>>> - if the nfs_client_id4 is the same, and
>>>>>> - if the flavor is auth_sys, and
>>>>>> - if the client IP address is different,
>>>>>> - then return NFS4ERR_INUSE.
>>>>>
>>>>> This still breaks for multi-homed servers and UCS clients. The
>>>>> client IP address can be different depending on what server IP
>>>>> address the client is accessing, but all the other parameters are
>>>>> the same.
>>>>
>>>> OK. So probably there's nothing we can do to help here.
>>>>
>>>> As a bandaid maybe a rate-limited log message ("clientid X now in
>>>> use
>>>> from IP Y") might help debug these things....
>>>
>>> Since you guys keep Cc'ing me, I'll chime in with a rather naive
>>> suggestion: if all that's required is a unique id for every client,
>>> why
>>> not use the MAC of the first network interface, independent of it
>>> being
>>> used for communication with the server?
>>>
>> I think this works fairly well for "real hardware", but I'm not so sure
>> about clients running in VMs. (I don't really know how the VMs assign
>> MAC addresses to their fake net interfaces and what uniqueness guarantees
>> those have. I remember the old freebie VMware client for Windows just
>> had a config file that assigned the MAC. I bet half the installations
>> on the planet had the same MAC as the default config file:-)
>
> But as I understand, the clientid doesn't have to globally unique, just
> unique for the given NFS server.
Global uniqueness is required to support Transparent State Migration.
> I think if you have two virtual
> machines with the same MAC connecting to the same NFS server, you have
> different problems anyway.
>
>
>> ps: Also, although it's not very relevant, getting the MAC address of
>> the first ethernet interface isn't easy in FreeBSD. I have no idea
>> if the same is true of Linux. (I'd also be worried that "first"
>> might not be fixed?)
>
> It doesn't need to be the same interface all the time, I just meant the
> first as in not a specific one.
The nfs_client_id4 string must not change across a reboot. Otherwise the server won't be able to figure out which open and lock state to discard when the client reboots.
>
>
> Best,
>
>
> -Nikolaus
>
> --
> »Time flies like an arrow, fruit flies like a Banana.«
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