I would *strongly* recommend against upgrading from 0.8 directly to 1.2. Skipping a major version is generally not recommended, skipped 3 would seem like carelessness.
> I second Romain, do the upgrade and make sure the health is good first. +1 but I would also recommend deciding if you actually need to use virtual nodes. The shuffle process can take a long time and people have had mixed experiences with it. If you wanted to move to 1.2 and get vNodes I would consider spinning up a new cluster and bulk loading into it. You could do an initial load and then to delta loads using snapshots, there would however be a period of stale data in the new cluster until the last delta snapshot is loaded. Cheers ----------------- Aaron Morton Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 27/07/2013, at 3:36 AM, David McNelis <dmcne...@gmail.com> wrote: > I second Romain, do the upgrade and make sure the health is good first. > > If you have or plan to have a large number of nodes, you might consider using > fewer than 256 as your initial vnodes amount. I think that number is > inflated from reasonable in the docs, as we've had some people talk about > potential performance degradation if you have a large number of nodes and a > very high number of vnodes, if I had it to do over again, I'd have done 64 > vnodes as my default (across 20 nodes). > > Another thing to be very cognizant of before shuffle is disk space. You > *must* have less than 50% used in order to do the shuffle successfully > because no data is removed (cleaned) from a node during the shuffle process > and the shuffle process essentially doubles the amount of data until you're > able to run a clean. > > > On Fri, Jul 26, 2013 at 11:25 AM, Romain HARDOUIN <romain.hardo...@urssaf.fr> > wrote: > Vnodes are a great feature. More nodes are involved during operations such as > bootstrap, decommission, etc. > DataStax documentation is definitely a must read. > That said, If I were you, I'd wait somewhat before to shuffle the ring. I'd > focus on cluster upgrade and monitoring the nodes. (number of files handles, > memory usage, latency, etc). > Upgrading from 0.8 to 1.2 can be tricky, there are so many changes since > then. Be careful about compaction strategies you choose and double check the > options. > > Regards, > Romain > > rash aroskar <rashmi.aros...@gmail.com> a écrit sur 25/07/2013 23:25:11 : > > > De : rash aroskar <rashmi.aros...@gmail.com> > > A : user@cassandra.apache.org, > > Date : 25/07/2013 23:25 > > Objet : cassandra 1.2.5- virtual nodes (num_token) pros/cons? > > > > Hi, > > I am upgrading my cassandra cluster from 0.8 to 1.2.5. > > In cassandra 1.2.5 the 'num_token' attribute confuses me. > > I understand that it distributes multiple tokens per node but I am > > not clear how that is helpful for performance or load balancing. Can > > anyone elaborate? has anyone used this feature and knows its > > advantages/disadvantages? > > > > Thanks, > > Rashmi >
