{"action":"closed","issue":{"url":"https://api.github.com/repos/neo4j/neo4j/issues/3535","labels_url":"https://api.github.com/repos/neo4j/neo4j/issues/3535/labels{/name}","comments_url":"https://api.github.com/repos/neo4j/neo4j/issues/3535/comments","events_url":"https://api.github.com/repos/neo4j/neo4j/issues/3535/events","html_url":"https://github.com/neo4j/neo4j/issues/3535","id":49987880,"number":3535,"title":"UnableToSampleException - when master fails in cluster.","user":{"login":"FylmTM","id":626772,"avatar_url":"https://avatars.githubusercontent.com/u/626772?v=3","gravatar_id":"","url":"https://api.github.com/users/FylmTM","html_url":"https://github.com/FylmTM","followers_url":"https://api.github.com/users/FylmTM/followers","following_url":"https://api.github.com/users/FylmTM/following{/other_user}","gists_url":"https://api.github.com/users/FylmTM/gists{/gist_id}","starred_url":"https://api.github.com/users/FylmTM/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/FylmTM/subscriptions","organizations_url":"https://api.github.com/users/FylmTM/orgs","repos_url":"https://api.github.com/users/FylmTM/repos","events_url":"https://api.github.com/users/FylmTM/events{/privacy}","received_events_url":"https://api.github.com/users/FylmTM/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/neo4j/neo4j/labels/bug","name":"bug","color":"fc2929"}],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":5,"created_at":"2014-11-25T08:16:34Z","updated_at":"2015-10-30T08:23:19Z","closed_at":"2015-10-30T08:23:19Z","body":"We have Neo4j cluster:\r\nA - Master instance\r\nB - Slave instance\r\nC - Slave instance\r\n\r\nIf master (`A`) was killed (e.g. `kill -9 <pid>`), then new master election was performed. After awhile `B` becomes master instance.\r\nThen, we try to bootup A instance. So, this instance was master before and now joins cluster as slave.\r\n`A` instance decides that he has wrong database version and downloads up-to-date version from master (`B`).\r\n\r\nAnd there is where error occurs. \r\n\r\n```\r\norg.neo4j.server.rrd.UnableToSampleException\r\n    at org.neo4j.server.rrd.sampler.NodeIdsInUseSampleable.getValue(NodeIdsInUseSampleable.java:47)\r\n    at org.neo4j.server.rrd.RrdSamplerImpl.updateSample(RrdSamplerImpl.java:59)\r\n    at org.neo4j.server.rrd.RrdJob.run(RrdJob.java:43)\r\n    at org.neo4j.server.rrd.ScheduledJob$1.run(ScheduledJob.java:41)\r\n    at java.util.TimerThread.mainLoop(Timer.java:555)\r\n    at java.util.TimerThread.run(Timer.java:505)\r\n```\r\n\r\nWe see this when log download is in process/finished. And this error continues to show endlessly:\r\n\r\n```\r\n2014-11-13 12:11:50.147+0000 INFO  [Cluster] Checking store consistency with master\r\n2014-11-13 12:11:50.853+0000 INFO  [Cluster] The store is inconsistent. Will treat it as branched and fetch a new one from the master\r\n2014-11-13 12:11:52.030+0000 INFO  [Cluster] Copying store from master\r\n... copying store\r\n... copying schema\r\n... copying logs\r\n2014-11-13 12:13:57.768+0000 INFO  [API] Server started on: http://0.0.0.0:7474/\r\n// it starts server, while logs download is in progress\r\n... org.neo4j.server.rrd.UnableToSampleException error loop\r\n```\r\n\r\nIf we restart this instance, then everything is OK. \r\n\r\nSo, in summary: we get `UnableToSampleException` error when try to bootup instance, that was master before, for first time.\r\n\r\nAny suggestions?\r\n\r\n--------\r\n\r\nNeo4j: 2.1.5 Enterprise\r\nOS: CentOS 6.5"}}