See if this helps with the concept you're working on: http://joejulian.name/blog/how-to-expand-glusterfs-replicated-clusters-by-one-server/ Michael Peek <peek at nimbios.org> wrote: >Hi Gluster gurus, > >I'm new to Gluster, so if there is a solution already talked about >somewhere then gladly point me to it and I'll get out of the way. That >said, here's my problem: > >I have four machines. Each machine is running Ubuntu 12.04 with >Gluster >3.2.5. Each machine has two drives: > >node1:/export/bricks/a >node1:/export/bricks/b >node2:/export/bricks/a >node2:/export/bricks/b >node3:/export/bricks/a >node3:/export/bricks/b >node4:/export/bricks/a >node4:/export/bricks/b > >I created a volume with a single replication, added the bricks, mounted >it to /mnt, and then created a file with "touch /mnt/this". The file >"this" appeared on the two bricks located on node1: > >node1:/export/bricks/a/this >and >node1:/export/bricks/b/this > >So if node1 goes down, all access to the file "this" is lost. It >seemed >to me that the order in which bricks were added dictated the >replication >location -- i.e. the second brick added is used as the replication >destination for the first brick, and so on with the 3rd and 4th pair of >bricks, 5th and 6th, etc. > >I've searched the archives, and this seems to be confirmed in a past >post located here: >http://supercolony.gluster.org/pipermail/gluster-users/2013-June/036272.html > >> Replica sets are done in order that the bricks are added to the >volume. >... >> So, you have an issue here, that both bricks of a replica set are on >the >> same host. > >Unfortunately, this was the end of the thread and no more information >was forthcoming. > >Now, I'm just starting out, and my volume is not yet used in >production, >so I have the luxury of removing all the bricks and then adding them >back in an order that allows for replication to be done across nodes >the >way that I want. But I see this as a serious problem. What happens >down the road when I need to expand? > >How would I add another machine as a node, and then add it's bricks, >and >still have replication done outside of that one machine? Is there a >way >to manually specify master/replication location? Is there a way to >reshuffle replicant brick on a running system? > >A couple of solutions have presented themselves to me: >1) Only add new nodes in pairs, and make sure to add bricks in the >correct order. >2) Only add new nodes in pairs, but setup two Gluster volumes and use >geo-replication (even though the geographical distance between the two >clusters may be as little as only 1 inch). >3) Only add new nodes in pairs, and use RAID or LVM to glue the drives >together, so that as far as Gluster is concerned, each node only has >one >brick. > >But each of these solutions involves adding new nodes in pairs, which >increases the incremental cost of expansion more than it feels like it >should. It just seems to me that there should be a smarter way to >handle things than what I'm seeing before me, so I'm hoping that I've >just missed something obvious. > >So what is the common wisdom among seasoned Gluster admins? > >Thanks for your help, > >Michael > > >------------------------------------------------------------------------ > >_______________________________________________ >Gluster-users mailing list >Gluster-users at gluster.org >http://supercolony.gluster.org/mailman/listinfo/gluster-users -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://supercolony.gluster.org/pipermail/gluster-users/attachments/20130708/871ef0f0/attachment.html>
