david@lang.hm wrote:

per the message below MD (or DM) would need to be modified to work 
reasonably well with one of the disk components being over an unreliable 
link (like a network link)

are the MD/DM maintainers interested in extending their code in this 
direction? or would they prefer to keep it simpler by being able to 
continue to assume that the raid components are connected over a highly 
reliable connection?

if they are interested in adding (and maintaining) this functionality 
then there is a real possibility that NBD+MD/DM could eliminate the need 
for DRDB. however if they are not interested in adding all the code to 
deal with the network type issues, then the argument that DRDB should 
not be merged becouse you can do the same thing with MD/DM + NBD is 
invalid and can be dropped/ignored

David Lang

As a user I'd like to see md/nbd be extended to cope with unreliable links.
I think md could be better in handling link exceptions. My unreliable memory 
recalls sporadic issues with hot-plug leaving md hanging and certain lower level 
errors (or even very high latency) causing unsatisfactory behaviour in what is 
supposed to be a fault 'tolerant' subsystem.


Would this just be relevant to network devices or would it improve support for 
jostled usb and sata hot-plugging I wonder?

David