Can you provide the schema and the queries? What is the RF of the keyspace for the data? Are you using any Retry policy on your Cluster object?
Sean Durity From: Marco Gasparini <marco.gaspar...@competitoor.com> Sent: Friday, December 21, 2018 10:45 AM To: user@cassandra.apache.org Subject: [EXTERNAL] Writes and Reads with high latency hello all, I have 1 DC of 3 nodes in which is running Cassandra 3.11.3 with consistency level ONE and Java 1.8.0_191. Every day, there are many nodejs programs that send data to the cassandra's cluster via NodeJs cassandra-driver. Every day I got like 600k requests. Each request makes the server to: 1_ READ some data in Cassandra (by an id, usually I get 3 records), 2_ DELETE one of those records 3_ WRITE the data into Cassandra. So every day I make many deletes. Every day I find errors like: "All host(s) tried for query failed. First host tried, 10.8.0.10:9042<https://urldefense.proofpoint.com/v2/url?u=http-3A__10.8.0.10-3A9042_&d=DwMFaQ&c=MtgQEAMQGqekjTjiAhkudQ&r=aC_gxC6z_4f9GLlbWiKzHm1vucZTtVYWDDvyLkh8IaQ&m=Y2zNzOyvqOiHqZ5yvB1rO_X6C-HivNjXYN0bLLL-yZQ&s=2v42cyvuxcXJ0oMfUrRcY-kRno1SkM4CTEMi4n1k0Wo&e=>: Host considered as DOWN. See innerErrors...." "Server timeout during write query at consistency LOCAL_ONE (0 peer(s) acknowledged the write over 1 required)...." "Server timeout during write query at consistency SERIAL (0 peer(s) acknowledged the write over 1 required)...." "Server timeout during read query at consistency LOCAL_ONE (0 peer(s) acknowledged the read over 1 required)...." nodetool tablehistograms tells me this: Percentile SSTables Write Latency Read Latency Partition Size Cell Count (micros) (micros) (bytes) 50% 8.00 379.02 1955.67 379022 8 75% 10.00 785.94 155469.30 654949 17 95% 12.00 17436.92 268650.95 1629722 35 98% 12.00 25109.16 322381.14 2346799 42 99% 12.00 30130.99 386857.37 3379391 50 Min 0.00 6.87 88.15 104 0 Max 12.00 43388.63 386857.37 20924300 179 in the 99% I noted that write and read latency is pretty high, but I don't know how to improve that. I can provide more statistics if needed. Is there any improvement I can make to the Cassandra's configuration in order to not to lose any data? Thanks Regards Marco ________________________________ The information in this Internet Email is confidential and may be legally privileged. It is intended solely for the addressee. Access to this Email by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted to be taken in reliance on it, is prohibited and may be unlawful. When addressed to our clients any opinions or advice contained in this Email are subject to the terms and conditions expressed in any applicable governing The Home Depot terms of business or client engagement letter. The Home Depot disclaims all responsibility and liability for the accuracy and content of this attachment and for any damages or losses arising from any inaccuracies, errors, viruses, e.g., worms, trojan horses, etc., or other items of a destructive nature, which may be contained in this attachment and shall not be liable for direct, indirect, consequential or special damages in connection with this e-mail message or its attachment.
