Recent discussion on dynamic snitch for some background http://www.mail-archive.com/user@cassandra.apache.org/msg12089.html
1) Adapted phi failure detector as used by gossip, see o.a.c.locator.DynamicEndpointSnitch 2) tracks last 100 responses from a node 3) in memory only 4) it's expensive when compared to storing a latency. It loops through all known nodes and calcs it's score which requires looping through all scores. Aaron On 9 Apr 2011, at 08:27, A J wrote: > dynamic_snitch seems to do host score calculation to figure the > latency of each node. > > What are the details of this calculation : > 1. What is the mechanism to determine latency ? > 2. Does it score the calculated scores and use the historical figures > to come up with the latest scores ? (You can't just base the latency > based on a singular ping) > 3. Where are these scores stored ? In the cassandra database somewhere ? > 4. cassandra.yaml also says that dynamic_snitch_update_interval_in_ms > "controls how often to perform the more expensive part of host score > calculation". What is the expensive part and how expensive is it? > > Thanks.
