Hi Austin, On Tue, Apr 24, 2012 at 9:31 AM, Swinney, Austin <aus...@vimeo.com> wrote:
> Hi, > > I'm using leveldb on a 5 node ec2 cluster. I've read about the basic tar > zipping of leveldb and ring files per node. Also, I read about riak-admin > backup all. > > I'm curious about a couple things. > > 1) is the `riak-admin backup all` command non-blocking? > Assuming you mean, "Will the cluster continue to work when I use this command?", then "Yes". :) > 2) is it a consistent backup or is consistency old fashioned thinking? > The backup will be complete up to the point at which it was taken. You'll get a dump of all the keys in the order in which they were listed. Updates that happened during the backup may or may not be captured. (I would have to verify exactly how you would know which made it and which didn't.) > 3) if you use the tar'ing up of leveldb + ring files per node, you lose > one node, then you restore it from this tar file that is hours or days old, > how does riak deal with bringing its data up to date? > > After you restored the node, it would gradually sync its replicas with those on the other nodes via read/repair. That said, doing a complete restore of the node would probably not be needed. When the node disappears, Riak will compensate for it by sending its writes/reads to fallback nodes. When it comes back online, hinted handoff and read repair will make sure it gets all the replicas it was supposed to have and that those replicas were up to date. (You will have to force Read Repar on the replicas on that node which can be done via a list keys or using an existing snippet of code [1] for doing this but be warned that it'll put some load on that node. We're working on making the Read Repair process less reactive in future releases, but this is the best way to do it right now.) To be clear, I'm in no way advocating not backing-up your data. You just might not need to use them in this situation. Another thing worth noting - the 'riak-admin backup' command is not known to be the speediest. If you have any non-trivial amount of data that needs backing up, you're probably best to do a FS snapshot of Level on each node. Unfortunately doing a live snapshot of Level is less than bulletproof at the moment, so you're advised to stop the node, snapshot level, and restart. You'll have to take the node offline for this but with five Riak nodes, your cluster should Just Keep Cranking™. Hope that helps. Mark [1] Fair warning: I'm not sure the last time this was tested - http://contrib.basho.com/bucket_inspector.html Thanks Riakers! > > Austin > > _______________________________________________ > riak-users mailing list > riak-users@lists.basho.com > http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com >
_______________________________________________ riak-users mailing list riak-users@lists.basho.com http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
