Ok. I saw dropped mutations on your cluster and full gc is a common cause for that.Can you just search the word GCInspector in system.log and share the frequency of minor and full gc. Moreover, are you printing promotion failures in gc logs?? Why full gc ia getting triggered??promotion failures or concurrent mode failures? If you are on CMS, you need to fine tune your heap options to address full gc.
ThanksAnuj Sent from Yahoo Mail on Android On Thu, 14 Jan, 2016 at 12:57 am, James Griffin<james.grif...@idioplatform.com> wrote: I think I was incorrect in assuming GC wasn't an issue due to the lack of logs. Comparing jstat output on nodes 2 & 3 show some fairly marked differences, though comparing the startup flags on the two machines show the GC config is identical.: $ jstat -gcutil S0 S1 E O P YGC YGCT FGC FGCT GCT2 5.08 0.00 55.72 18.24 59.90 25986 619.827 28 1.597 621.4243 0.00 0.00 22.79 17.87 59.99 422600 11225.979 668 57.383 11283.361 Here's typical output for iostat on nodes 2 & 3 as well: $ iostat -dmx md0 Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await r_await w_await svctm %util2 md0 0.00 0.00 339.00 0.00 9.77 0.00 59.00 0.00 0.00 0.00 0.00 0.00 0.003 md0 0.00 0.00 2069.00 1.00 85.85 0.00 84.94 0.00 0.00 0.00 0.00 0.00 0.00 Griff On 13 January 2016 at 18:36, Anuj Wadehra <anujw_2...@yahoo.co.in> wrote: Node 2 has slightly higher data but that should be ok. Not sure how read ops are so high when no IO intensive activity such as repair and compaction is running on node 3.May be you can try investigating logs to see whats happening. Others on the mailing list could also share their views on the situation. ThanksAnuj Sent from Yahoo Mail on Android On Wed, 13 Jan, 2016 at 11:46 pm, James Griffin<james.grif...@idioplatform.com> wrote: Hi Anuj, Below is the output of nodetool status. The nodes were replaced following the instructions in Datastax documentation for replacing running nodes since the nodes were running fine, it was that the servers had been incorrectly initialised and they thus had less disk space. The status below shows 2 has significantly higher load, however as I say 2 is operating normally and is running compactions, so I guess that's not an issue? Datacenter: datacenter1=======================Status=Up/Down|/ State=Normal/Leaving/Joining/Moving-- Address Load Tokens Owns Host ID RackUN 1 253.59 GB 256 31.7% 6f0cfff2-babe-4de2-a1e3-6201228dee44 rack1UN 2 302.23 GB 256 35.3% faa5b073-6af4-4c80-b280-e7fdd61924d3 rack1UN 3 265.02 GB 256 33.1% 74b15507-db5c-45df-81db-6e5bcb7438a3 rack1 Griff On 13 January 2016 at 18:12, Anuj Wadehra <anujw_2...@yahoo.co.in> wrote: Hi, Revisiting the thread I can see that nodetool status had both good and bad nodes at same time. How do you replace nodes? When you say bad node..I understand that the node is no more usable even though Cassandra is UP? Is that correct? If a node is in bad shape and not working, adding new node may trigger streaming huge data from bad node too. Have you considered using the procedure for replacing a dead node? Please share Latest nodetool status. nodetool output shared earlier: `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 ThanksAnuj Sent from Yahoo Mail on Android On Wed, 13 Jan, 2016 at 10:34 pm, James Griffin<james.grif...@idioplatform.com> wrote: Hi all, We’ve spent a few days running things but are in the same position. To add some more flavour: - We have a 3-node ring, replication factor = 3. We’ve been running in this configuration for a few years without any real issues - Nodes 2 & 3 are much newer than node 1. These two nodes were brought in to replace two other nodes which had failed RAID0 configuration and thus were lacking in disk space. - When node 2 was brought into the ring, it exhibited high CPU wait, IO and load metrics - We subsequently brought 3 into the ring: as soon as 3 was fully bootstrapped, the load, CPU wait and IO stats on 2 dropped to normal levels. Those same stats on 3, however, sky-rocketed - We’ve confirmed configuration across all three nodes are identical and in line with the recommended production settings - We’ve run a full repair - Node 2 is currently running compactions, 1 & 3 aren’t and have no pending - There is no GC happening from what I can see. Node 1 has a GC log, but that’s not been written to since May last year What we’re seeing at the moment is similar and normal stats on nodes 1 & 2, but high CPU wait, IO and load stats on 3. As a snapshot: - Load: 3.96, CPU wait: 30.8%, Disk Read Ops: 408/s - Load: 5.88, CPU wait: 14.6%, Disk Read Ops: 275/s - Load: 58.15, CPU wait: 87.0%, Disk Read Ops: 2,408/s Can you recommend any next steps? Griff On 6 January 2016 at 17:31, Anuj Wadehra <anujw_2...@yahoo.co.in> wrote: 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
