[Gluster-devel] question on AFR behavior when master is down

Gerry Reno greno at verizon.net
Fri Jul 20 17:18:28 UTC 2007


Every so often it is necessary to bring machines down for some type of 
maintenance.  If the machine is part of a glusterfs AFR replication 
setup what will happen in the following scenarios?:

master (brick1) is brought down, files are added, changed and deleted on 
glusterfs, master is brought back up.  Does the master(brick1) resume 
it's master role?  If so, does it sync and correctly add/chg/del files 
to its brick that were modified while it was down?

slave (brick3) is brought down, files are added, changed and deleted on 
glusterfs, slave is brought back up.  Since the cluster had a slave 
removed from the middle of the order the replication specified in the 
config may change on other bricks I assume during the down time.  Does 
this all get straightened out when this slave returns to the cluster?  
In other words I may replicate over the first three bricks for some 
files therefore while brick3 is down brick4 would actually become the 
third brick in the cluster then.  Would it be receiving the replication 
intended for brick3?  Again, when brick3 restarts does this all get 
straightened out.  In other words, does brick4 get cleaned up and 
unintended files removed that were replicated to it when brick3 was down?







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