Hey Aaron, I increased the size of the cluster also the concurrent_writes parameter. Still there is a node which keeps on dropping the mutation messages. The other nodes are not dropping mutation messages. I am using Hector API and had done nothing for load balancing so far. Just provided the host:port of the nodes in the Cassandrahostconfig. Is this due to some improper load balancing? Also the physical host where the node is hosted is relatively heavier than other nodes' host. What can I do to improve? PS: The node is seed of the cluster.
Thanks, Dushyant From: aaron morton [mailto:aa...@thelastpickle.com] Sent: Monday, March 05, 2012 4:15 PM To: user@cassandra.apache.org Subject: Re: Mutation Dropped Messages 1. Which parameters to tune in the config files? - Especially looking for heavy writes The node is overloaded. It may be because there are no enough nodes, or the node is under temporary stress such as GC or repair. If you have spare IO / CPU capacity you could increase the current_writes to increase throughput on the write stage. You then need to ensure the commit log and, to a lesser degree, the data volumes can keep up. 2. What is the difference between TimedOutException and silently dropping mutation messages while operating on a CL of QUORUM. TimedOutExceptions means CL nodes did not respond to the coordinator before rpc_timeout. Dropping messages happens when a message is removed from the queue in the a thread pool after rpc_timeout has occurred. it is a feature of the architecture, and correct behaviour under stress. Inconsistencies created by dropped messages are repaired via reads as high CL, HH (in 1.+), Read Repair or Anti Entropy. Cheers ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 5/03/2012, at 11:32 PM, Tiwari, Dushyant wrote: Hi All, While benchmarking Cassandra I found "Mutation Dropped" messages in the logs. Now I know this is a good old question. It will be really great if someone can provide a check list to recover when such a thing happens. I am looking for answers of the following questions - 1. Which parameters to tune in the config files? - Especially looking for heavy writes 2. What is the difference between TimedOutException and silently dropping mutation messages while operating on a CL of QUORUM. Regards, Dushyant ________________________________ NOTICE: Morgan Stanley is not acting as a municipal advisor and the opinions or views contained herein are not intended to be, and do not constitute, advice within the meaning of Section 975 of the Dodd-Frank Wall Street Reform and Consumer Protection Act. If you have received this communication in error, please destroy all electronic and paper copies and notify the sender immediately. Mistransmission is not intended to waive confidentiality or privilege. Morgan Stanley reserves the right, to the extent permitted under applicable law, to monitor electronic communications. This message is subject to terms available at the following link: http://www.morganstanley.com/disclaimers. If you cannot access these links, please notify us by reply message and we will send the contents to you. By messaging with Morgan Stanley you consent to the foregoing. -------------------------------------------------------------------------- NOTICE: Morgan Stanley is not acting as a municipal advisor and the opinions or views contained herein are not intended to be, and do not constitute, advice within the meaning of Section 975 of the Dodd-Frank Wall Street Reform and Consumer Protection Act. If you have received this communication in error, please destroy all electronic and paper copies and notify the sender immediately. Mistransmission is not intended to waive confidentiality or privilege. Morgan Stanley reserves the right, to the extent permitted under applicable law, to monitor electronic communications. This message is subject to terms available at the following link: http://www.morganstanley.com/disclaimers. If you cannot access these links, please notify us by reply message and we will send the contents to you. By messaging with Morgan Stanley you consent to the foregoing.
