> As soon as one CF is created, the column changes to Effective Ownership There has to be a user defined keyspace to calculate effective ownership.
Effective Ownership is calculated for all keyspaces if the share the same RF, and for a named KS if specified. It's the % of the total cluster data stored on that node for the named KS or all keyspaces. Cheers ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 14/11/2012, at 9:43 AM, Wei Zhu <wz1...@yahoo.com> wrote: > I am new to Cassandra, and 1.1.6 is the only version I have tested. Not sure > about the old behavior, for 1.1.6, my observation is that for brand new > cluster (with no CF created), it shows Ownership from nodetool ring, the > value is 100/<nodes>. As soon as one CF is created, the column changes to > Effective Ownership and the formula seems to be 100*<replication > factor>/<nodes> as Kirk mentioned. .Theoretically, different keyspace can > have different replication factor. Not sure how Effective Ownership is > calculated in that cases. Just curious anyone knows? > > Thanks. > -Wei > > From: Kirk True <k...@mustardgrain.com> > To: user@cassandra.apache.org > Sent: Monday, November 12, 2012 4:24 PM > Subject: Re: read request distribution > > Somewhat recently the Ownership column was changed to Effective Ownership. > > Previously the formula was essentially 100/<nodes>. Now it's 100*<replication > factor>/<nodes>. So in previous releases of Cassandra it would be 100/12 = > 8.33, now it would be closer to 25% (8.33*3 (assuming a replication factor of > three)). > > Kirk > > On Mon, Nov 12, 2012, at 03:52 PM, Ananth Gundabattula wrote: >> Hi all, >> >> On an unrelated observation of the below readings, it looks like all the 3 >> nodes own 100% of the data. This confuses me a bit. We have a 12 node >> cluster with RF=3 but the effective ownership is shown as 8.33 % . >> >> So here is my question. How is the ownership calculated : Is Replica factor >> considered in the ownership calculation ? ( If yes , then 8.33 % ownership >> of a cluster seems wrong to me . If not 100% ownership for a node cluster >> seems wrong to me. Am I missing something in the calculation? >> >> Regards, >> Ananth >> >> On Fri, Nov 9, 2012 at 4:37 PM, Wei Zhu <wz1...@yahoo.com> wrote: >> Hi All, >> I am doing a benchmark on a Cassandra. I have a three node cluster with >> RF=3. I generated 6M rows with sequence number from 1 to 6m, so the rows >> should be evenly distributed among the three nodes disregarding the >> replicates. >> I am doing a benchmark with read only requests, I generate read request for >> randomly generated keys from 1 to 6M. Oddly, nodetool cfstats, reports that >> one node has only half the requests as the other one and the third node sits >> in the middle. So the ratio is like 2:3:4. The node with the most read >> requests actually has the smallest latency and the one with the least read >> requests reports the largest latency. The difference is pretty big, the >> fastest is almost double the slowest. >> All three nodes have the exactly the same hardware and the data size on each >> node are the same since the RF is three and all of them have the complete >> data. I am using Hector as client and the random read request are in >> millions. I can't think of a reasonable explanation. Can someone please >> shed some lights? >> >> Thanks. >> -Wei > >
