[lustre-discuss] design to enable kernel updates

[Brian Andrus]

All,

I have been contemplating how lustre could be configured such that I 
could update the kernel on each server without downtime.

It seems this is _almost_ possible when you have a san system so you 
have failover for OSTs and MDTs. BUT the MGS/MGT seems to be the 
problematic one, since rebooting that seems cause downtime that cannot 
be avoided.

If you have a system where the disks are physically part of the OSS 
hardware, you are out of luck. The hypothetical scenario I am using is 
if someone had a VM that was a qcow image on a lustre mount (basically 
an active, open file being read/written to continuously). How could 
lustre be built to ensure anyone on the VM would not notice a kernel 
upgrade to the underlying lustre servers.


Could such a setup be done? It seems that would be a better use case for 
something like GPFS or Gluster, but being a die-hard lustre enthusiast, 
I want to at least show it could be done.


Thanks in advance,

Brian Andrus