1. One node is running at 8G rest on 10G - same config
2. Nodetool -
Status State Load Owns Token
162563731948587347959549934419333022646
Up Normal 107.79 MB 25.00% 34957844353235424160784456632419943350
Up Normal 116.44 MB 25.00% 77493140218352732093706282561390969782
Up Normal 27.01 MB 12.68% 99065646426277998282363457251162269147
Up Normal 35.9 MB 12.32% 120028436083470040026628108490361996214
Up Normal 512.55 KB 25.00% 162563731948587347959549934419333022646
RF:2 and CL: QUORUM - writes at a rate of 1750 rows/s - every row - 5 cols and
2 of them indexes.
Thanks,
Dushyant
From: aaron morton [mailto:[email protected]]
Sent: Monday, March 05, 2012 11:07 PM
To: [email protected]
Subject: Re: Mutation Dropped Messages
I increased the size of the cluster also the concurrent_writes parameter. Still
there is a node which keeps on dropping the mutation messages.
Ensure all the nodes have the same spec, and the nodes have the same config. In
a virtual environment consider moving the node.
Is this due to some improper load balancing?
What does nodetool ring say and what sort of queries (and RF and CL) are you
sending.
Cheers
-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com
On 6/03/2012, at 3:58 AM, Tiwari, Dushyant wrote:
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:[email protected]]
Sent: Monday, March 05, 2012 4:15 PM
To: [email protected]<mailto:[email protected]>
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
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