http://wiki.apache.org/cassandra/Operations
On Fri, Feb 19, 2010 at 3:03 PM, Weijun Li <weiju...@gmail.com> wrote: > I setup a two cassandra clusters with 2 nodes each. Both use random > partitioner. It's strange that for each cluster, one node has much shortter > read latency than the other one > > This is the info of one of the cluster: > > Node A: read count 77302, data file 41GB, read latency 58180, io saturation > 100% > Node B: read count 488753, data file 26GB, read latency 5822 , io saturation > 35%. > > I first started node A, then ran B to join the cluster. Both machines have > exactly the same hardware and OS. The test client randomly pick a node to > write and it worked fine for the other cluster. > > Address Status Load > Range Ring > > 169400792707028208569145873749456918214 > 10.xxxxxxx Up 38.39 GB > 103633195217832666843316719920043079797 |<--| > 10.xxxxxxx Up 24.22 GB > 169400792707028208569145873749456918214 |-->| > > For both clusters, whichever node that took more reads (with larger data > file) owns the much worse read latency. > > What's the algorithm that cassandra use to split token when a new node is > joining? What could cause this unbalanced read latency issue? How can I fix > this? How to make sure all nodes get evenly distributed data and traffic? > > -Weijun >
