Re: VFS ROADMAP (and vfs01.patch stage 1 available for testing)

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

:>>So, simply put (as far as I can understand this material), DragonFly 
:>>will provide an API that has the hardware abstracted to an virtual 
:>>hardware (which is clusterable over multiple nodes with different types 
:>>of machine) kind of a distributed virtual machine (DVM)
:
:How would such a system gracefully deal with hardware failures?  What 
:happens when one of the nodes in the cluster dies?
 
    This is a question with a very, very complex answer.  If I were to
    try to simplify it and put it in layman's terms, we will almost 
    certainly have to use the resource accessibility model.  So what
    happens would depend on what was running on the node that went down
    and whether the resources are recoverable or not.  Processes beholden
    to the dead node or needing critical resources (like memory) on the dead
    node would probably be killed by default.  Recoverable resources, such
    as a block device representing a physical disk, could result in 
    dependant proceses blocking until the resource becomes available again.
    If the block device is part of a RAID then theoretically dependant
    processes would still be able to run as long as the RAID as a whole 
    remains intact.
 
					-Matt
					Matthew Dillon 
					<dillon@xxxxxxxxxxxxx>