Hi Vickrum, I would have proceeded with diagnosis as follows: 1. Analysis of sar report to check system health -cpu memory swap disk etc. System seems to be overloaded. This is evident from mutation drops. 2. Make sure that all recommended Cassandra production settings available at Datastax site are applied ,disable zone reclaim and THP. 3.Run full Repair on bad node and check data size. Node is owner of maximum token range but has significant lower data.I doubt that bootstrapping happened properly. 4.Compactionstats shows 22 pending compactions. Try throttling compactions via reducing cincurent compactors or compaction throughput. 5.Analyze logs to make sure bootstrapping happened without errors. 6. Look for other common performance problems such as GC pauses to make sure that dropped mutations are not caused by GC pauses.
ThanksAnuj Sent from Yahoo Mail on Android On Wed, 6 Jan, 2016 at 10:12 pm, Vickrum Loi<vickrum....@idioplatform.com> wrote: # nodetool compactionstats pending tasks: 22 compaction type keyspace table completed total unit progress Compactionproduction_analytics interactions 240410213 161172668724 bytes 0.15% Compactionproduction_decisionsdecisions.decisions_q_idx 120815385 226295183 bytes 53.39% Active compaction remaining time : 2h39m58s Worth mentioning that compactions haven't been running on this node particularly often. The node's been performing badly regardless of whether it's compacting or not. On 6 January 2016 at 16:35, Jeff Ferland <j...@tubularlabs.com> wrote: What’s your output of `nodetool compactionstats`? On Jan 6, 2016, at 7:26 AM, Vickrum Loi <vickrum....@idioplatform.com> wrote: Hi, We recently added a new node to our cluster in order to replace a node that died (hardware failure we believe). For the next two weeks it had high disk and network activity. We replaced the server, but it's happened again. We've looked into memory allowances, disk performance, number of connections, and all the nodetool stats, but can't find the cause of the issue. `nodetool tpstats`[0] shows a lot of active and pending threads, in comparison to the rest of the cluster, but that's likely a symptom, not a cause. `nodetool status`[1] shows the cluster isn't quite balanced. The bad node (D) has less data. Disk Activity[2] and Network activity[3] on this node is far higher than the rest. The only other difference this node has to the rest of the cluster is that its on the ext4 filesystem, whereas the rest are ext3, but we've done plenty of testing there and can't see how that would affect performance on this node so much. Nothing of note in system.log. What should our next step be in trying to diagnose this issue? Best wishes, Vic [0] `nodetool tpstats` output: Good node: Pool Name Active Pending Completed Blocked All time blocked ReadStage 0 0 46311521 0 0 RequestResponseStage 0 0 23817366 0 0 MutationStage 0 0 47389269 0 0 ReadRepairStage 0 0 11108 0 0 ReplicateOnWriteStage 0 0 0 0 0 GossipStage 0 0 5259908 0 0 CacheCleanupExecutor 0 0 0 0 0 MigrationStage 0 0 30 0 0 MemoryMeter 0 0 16563 0 0 FlushWriter 0 0 39637 0 26 ValidationExecutor 0 0 19013 0 0 InternalResponseStage 0 0 9 0 0 AntiEntropyStage 0 0 38026 0 0 MemtablePostFlusher 0 0 81740 0 0 MiscStage 0 0 19196 0 0 PendingRangeCalculator 0 0 23 0 0 CompactionExecutor 0 0 61629 0 0 commitlog_archiver 0 0 0 0 0 HintedHandoff 0 0 63 0 0 Message type Dropped RANGE_SLICE 0 READ_REPAIR 0 PAGED_RANGE 0 BINARY 0 READ 640 MUTATION 0 _TRACE 0 REQUEST_RESPONSE 0 COUNTER_MUTATION 0 Bad node: Pool Name Active Pending Completed Blocked All time blocked ReadStage 32 113 52216 0 0 RequestResponseStage 0 0 4167 0 0 MutationStage 0 0 127559 0 0 ReadRepairStage 0 0 125 0 0 ReplicateOnWriteStage 0 0 0 0 0 GossipStage 0 0 9965 0 0 CacheCleanupExecutor 0 0 0 0 0 MigrationStage 0 0 0 0 0 MemoryMeter 0 0 24 0 0 FlushWriter 0 0 27 0 1 ValidationExecutor 0 0 0 0 0 InternalResponseStage 0 0 0 0 0 AntiEntropyStage 0 0 0 0 0 MemtablePostFlusher 0 0 96 0 0 MiscStage 0 0 0 0 0 PendingRangeCalculator 0 0 10 0 0 CompactionExecutor 1 1 73 0 0 commitlog_archiver 0 0 0 0 0 HintedHandoff 0 0 15 0 0 Message type Dropped RANGE_SLICE 130 READ_REPAIR 1 PAGED_RANGE 0 BINARY 0 READ 31032 MUTATION 865 _TRACE 0 REQUEST_RESPONSE 7 COUNTER_MUTATION 0 [1] `nodetool status` output: Status=Up/Down |/ State=Normal/Leaving/Joining/Moving -- Address Load Tokens Owns Host ID Rack UN A (Good) 252.37 GB 256 23.0% 9cd2e58c-a062-48a4-8d3f-b7bd9ee0576f rack1 UN B (Good) 245.91 GB 256 24.4% 6f0cfff2-babe-4de2-a1e3-6201228dee44 rack1 UN C (Good) 254.79 GB 256 23.7% f4891729-9179-4f19-ab2c-50d387da7ac6 rack1 UN D (Bad) 163.85 GB 256 28.8% faa5b073-6af4-4c80-b280-e7fdd61924d3 rack1 [2] Disk read/write ops: https://s3-eu-west-1.amazonaws.com/uploads-eu.hipchat.com/28299/178477/dRs4jV1ukMeFHGE/cass-disk-read-ops.png https://s3-eu-west-1.amazonaws.com/uploads-eu.hipchat.com/28299/178477/gbE58N2WosiOomF/cass-disk-write-ops.png [3] Network in/out: https://s3-eu-west-1.amazonaws.com/uploads-eu.hipchat.com/28299/178477/RwOVdUBxu6fPLgF/cass-network-in.png https://s3-eu-west-1.amazonaws.com/uploads-eu.hipchat.com/28299/178477/OpZM6ypNVN0O30q/cass-network-out.png
