[OpenAFS-devel] RFC: Status returned by vos for pre-attached volumes on demand-attach

[Alistair Ferguson]

Hi,

Jeffrey Altman wrote:
> Alistair Ferguson wrote:
>   
>> There are at least four options:
>> 1. expose all underlying states to vos examine
>> 2. expose pre-attached to vos examine
>> 3. convert pre-attached to on-line for vos (the current behavior)
>> 4. convert pre-attached to off-line for vos
>>
>> Option 3 is currently implemented and is the least desirable.
>>
>> Our suggestion is that we implement option 1, which will require
>> exposing the current volume state onto the inUse field in the
>> FillVolInfo function in the volserver.  The vos command would need to be
>> modified to be aware of the new values, but unmodified vos commands
>> would report off-line for volumes in a
>> state other than fully attached.
>>
>> Note that options 1 and 2 involve a change in behaviour for sites running
>> demand-attach.
>>     
>
> The Windows client performs extensive volume status monitoring in order
> to export that status info to third party kernel drivers that can use
> that state info to fail over between cell clones or redirect offline
> paths to alternate locations.   As part of this logic,
> RXAFS_GetVolumeStatus is executed on inaccessible volumes to obtain
> their current status.   From the perspective of the clients that are
> currently shipping, option 3 is the most desirable and option 4 will
> break them.
>   

Okay, that's what's implemented at the moment.


> I appreciate the desire to export additional information.  I believe
> that this should be done by a new RPC, RXAFS_GetVolumeStatus2, that
> documents the new states and their meanings.  Clients that use the new
> RPC will be expected to be knowledgeable of the new states.
>
> A proposal to implement this new RPC should be made to the
> afs3-standardization mailing list.
>   

Okay, will do.  Thanks for your comments.


ali