[OpenAFS-devel] Cache Volumes

[Derrick J Brashear]

On Mon, 4 Jun 2007, Steven Jenkins wrote:

>> Which brings me to my question. A cache volume is my idea of a solution.
>> It would be similar to a replication site with the exception of users being
>> able to write to it. I understand why users can't write to normal
>> replication sites so I'd assume the cache volume would need the additional
>> stipulation of it can only be used when the real volume exists and is
>> online. Files will need to copied to the remote server, this can I suppose
>> be done through making the client wait till done, or letting the cache
>> volume accept it and background send it. Second one would be preferred of
>> course, but does have the problem of it the user beats the upload to the
>> other office.
>> 
>
> Your proposal would be a very large change to how AFS works.  However, on a
> small scale, you might accomplish similar functionality manually via
> examining the cache and doing vos move's.  As the number of users increases
> (and especially the number of shared volumes) , you'll need to re-architect
> a solution.  But I suspect that solution can be more easily layered on top
> of AFS rather than done in AFS itself.

Actually, in some sense code to do this exists but is out of date. the 
CITI folks had something called "iafs", which was basically "make my cache 
manager also be a server". The access control model is of course going to 
be fun, but it's doable.


Of course this is a development solution, not something you can roll out 
of a box today, so Steven's answer is probably the one you want as an end 
user unless you have a longer time scale in mind for this and have time or 
resources to throw at fixing the problem.