[jira] [Assigned] (CASSANDRA-7567) when the commit_log disk for a single node is overwhelmed the entire cluster slows down
[ https://issues.apache.org/jira/browse/CASSANDRA-7567?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Ryan McGuire reassigned CASSANDRA-7567: --- Assignee: Ryan McGuire when the commit_log disk for a single node is overwhelmed the entire cluster slows down --- Key: CASSANDRA-7567 URL: https://issues.apache.org/jira/browse/CASSANDRA-7567 Project: Cassandra Issue Type: Bug Components: Core Environment: debian 7.5, bare metal, 14 nodes, 64CPUs, 64GB RAM, commit_log disk sata, data disk SSD, vnodes, leveled compaction strategy Reporter: David O'Dell Assignee: Ryan McGuire Attachments: 7567.logs.bz2, write_request_latency.png We've run into a situation where a single node out of 14 is experiencing high disk io. This can happen when a node is being decommissioned or after it joins the ring and runs into the bug cassandra-6621. When this occurs the write latency for the entire cluster spikes. From 0.3ms to 170ms. To simulate this simply run dd on the commit_log disk (dd if=/dev/zero of=/tmp/foo bs=1024) and you will see that instantly all nodes in the cluster have slowed down. BTW overwhelming the data disk does not have this same effect. Also I've tried this where the overwhelmed node isn't being connected directly from the client and it still has the same effect. -- This message was sent by Atlassian JIRA (v6.2#6252)
[jira] [Assigned] (CASSANDRA-7567) when the commit_log disk for a single node is overwhelmed the entire cluster slows down
[ https://issues.apache.org/jira/browse/CASSANDRA-7567?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Ryan McGuire reassigned CASSANDRA-7567: --- Assignee: Brandon Williams (was: Ryan McGuire) when the commit_log disk for a single node is overwhelmed the entire cluster slows down --- Key: CASSANDRA-7567 URL: https://issues.apache.org/jira/browse/CASSANDRA-7567 Project: Cassandra Issue Type: Bug Components: Core Environment: debian 7.5, bare metal, 14 nodes, 64CPUs, 64GB RAM, commit_log disk sata, data disk SSD, vnodes, leveled compaction strategy Reporter: David O'Dell Assignee: Brandon Williams Attachments: 7567.logs.bz2, write_request_latency.png We've run into a situation where a single node out of 14 is experiencing high disk io. This can happen when a node is being decommissioned or after it joins the ring and runs into the bug cassandra-6621. When this occurs the write latency for the entire cluster spikes. From 0.3ms to 170ms. To simulate this simply run dd on the commit_log disk (dd if=/dev/zero of=/tmp/foo bs=1024) and you will see that instantly all nodes in the cluster have slowed down. BTW overwhelming the data disk does not have this same effect. Also I've tried this where the overwhelmed node isn't being connected directly from the client and it still has the same effect. -- This message was sent by Atlassian JIRA (v6.2#6252)
