mogilefs in multiple locations, tracker issue

[dormando]

> 1.       If a user from Japan uploading a file to Tracker02 server in 
> Japan.  Will the Tracker02 server “CREATE_OPEN” in Storage02 server 
> first?? Is there a “priority” storage list for specific tracker?

Not by default, nope.

> 2.       If user upload a 50MB file to Storage02 through Tracker02 in 
> Japan.  Immediately, a user from USA, request a “GET_PATHS” from 
> Tracker01, I know Tracker01 will return Storage02, since it takes some 
> time to replicate to Storage01.  How about AFTER the replication is 
> finished?  Can Tracker01 return Storage01 as first priority since user 
> is coming from USA?

It would be a bit of work but I don't see it being impossible. Again, 
not by default.

> 3.       Regarding replication policy, if I am going to override the 
> function “replicate_to”, how can I plug this new class into the server? 
>  i.e. I have already installed 2.17.  Sorry, but I am a newbie in PERL…

You need to write your own replication policy and plug that in. You 
might need someone with a bit of perl experience to do this. It's not 
easy, but not necessarily hard either.

> 
> I know some of the issues could be resolved by using geographic load 
> balancing.  I can make sure a user from Japan goes to Japan web server 
> and tracker.  However, I don’t know how a Tracker select it’s storage 
> location.

It just picks them out of a hat based on some simple criteria :)

If you need help, I know some of us do contract work and could 
potentially figure something out. I'd love to have more of this support 
back in mogilefs as well! It's the same concept for multiple datacenter 
support anywhere.

-Dormando