[Gluster-users] Glusterfs Rack-Zone Awareness feature...

[Jeff Darcy]

> When I create a new replicated volume, using only 2 nodes, I use this command
> line : ‘gluster volume create vol_name replica 2 transport tcp server1
> :/export/brick1/1 server2 :/export/brick1/1’
> server1 and server2 are in 2 different datacenters.
> Now, if I want to expand gluster volume, using 2 new servers (ex : server3
> and server4) , I use those command lines :
> ‘gluster volume add-brick vol_name server3: /export/brick1/1’
> ‘gluster volume add-brick vol_name server4: /export/brick1/1’
> ‘gluster volume rebalance vol_name fix-layout start’
> ‘gluster volume rebalance vol_name start’
> How the rebalance command work ?
> How to be sure that replicated data are not stored on servers hosted in the
> same datacenter ?

he replica count.  Some of the infrastructure we need for the "data
classification" task in 3.6 will allow us to relax that limitation and
even support multiple replica counts within one volume, but for the
simple/general case that probably won't be until 3.7 or later.  For now,
we ensure when a volume is created or bricks are added that the bricks
within each replica set are not co-located.

Also, since this is the first time I've noticed a mention of multiple
*data centers* (as opposed to multiple racks within one data center),
it's important to note that AFR will fall down quite badly if the
latency is greater than a few milliseconds.  NSR will be much better at
handling such environments, but won't be available for a while yet.

Yeah, I'm also frustrated that all the good stuff always seems to be in
the future.  ;)