Compaction is backed up that may be normal write load (because of the rack
imbalance), or it may be a secondary index build. Hard to say for sure.
nodetool compactionstats¹ if you¹re able to provide it. The jstack probably
not necessary, streaming is being marked as failed and it¹s turning itself
off. Not sure why streaming is marked as failing, though, anything on the
sending sides?
From: Brian Spindler <brian.spind...@gmail.com>
Reply-To: <user@cassandra.apache.org>
Date: Saturday, August 12, 2017 at 6:34 PM
To: <user@cassandra.apache.org>
Subject: Re: Dropping down replication factor
Thanks for replying Jeff.
Responses below.
On Sat, Aug 12, 2017 at 8:33 PM Jeff Jirsa <jji...@gmail.com> wrote:
> Answers inline
>
> --
> Jeff Jirsa
>
>
>> > On Aug 12, 2017, at 2:58 PM, brian.spind...@gmail.com wrote:
>> >
>> > Hi folks, hopefully a quick one:
>> >
>> > We are running a 12 node cluster (2.1.15) in AWS with Ec2Snitch. It's all
>> in one region but spread across 3 availability zones. It was nicely balanced
>> with 4 nodes in each.
>> >
>> > But with a couple of failures and subsequent provisions to the wrong az we
>> now have a cluster with :
>> >
>> > 5 nodes in az A
>> > 5 nodes in az B
>> > 2 nodes in az C
>> >
>> > Not sure why, but when adding a third node in AZ C it fails to stream after
>> getting all the way to completion and no apparent error in logs. I've looked
>> at a couple of bugs referring to scrubbing and possible OOM bugs due to
>> metadata writing at end of streaming (sorry don't have ticket handy). I'm
>> worried I might not be able to do much with these since the disk space usage
>> is high and they are under a lot of load given the small number of them for
>> this rack.
>
> You'll definitely have higher load on az C instances with rf=3 in this ratio
>
> Streaming should still work - are you sure it's not busy doing something? Like
> building secondary index or similar? jstack thread dump would be useful, or at
> least nodetool tpstats
>
Only other thing might be a backup. We do incrementals x1hr and snapshots
x24h; they are shipped to s3 then links are cleaned up. The error I get on
the node I'm trying to add to rack C is:
ERROR [main] 2017-08-12 23:54:51,546 CassandraDaemon.java:583 - Exception
encountered during startup
java.lang.RuntimeException: Error during boostrap: Stream failed
at
org.apache.cassandra.dht.BootStrapper.bootstrap(BootStrapper.java:87)
~[apache-cassandra-2.1.15.jar:2.1.15]
at
org.apache.cassandra.service.StorageService.bootstrap(StorageService.java:11
66) ~[apache-cassandra-2.1.15.jar:2.1.15]
at
org.apache.cassandra.service.StorageService.joinTokenRing(StorageService.jav
a:944) ~[apache-cassandra-2.1.15.jar:2.1.15]
at
org.apache.cassandra.service.StorageService.initServer(StorageService.java:7
40) ~[apache-cassandra-2.1.15.jar:2.1.15]
at
org.apache.cassandra.service.StorageService.initServer(StorageService.java:6
17) ~[apache-cassandra-2.1.15.jar:2.1.15]
at
org.apache.cassandra.service.CassandraDaemon.setup(CassandraDaemon.java:391)
[apache-cassandra-2.1.15.jar:2.1.15]
at
org.apache.cassandra.service.CassandraDaemon.activate(CassandraDaemon.java:5
66) [apache-cassandra-2.1.15.jar:2.1.15]
at
org.apache.cassandra.service.CassandraDaemon.main(CassandraDaemon.java:655)
[apache-cassandra-2.1.15.jar:2.1.15]
Caused by: org.apache.cassandra.streaming.StreamException: Stream failed
at
org.apache.cassandra.streaming.management.StreamEventJMXNotifier.onFailure(S
treamEventJMXNotifier.java:85) ~[apache-cassandra-2.1.15.jar:2.1.15]
at
com.google.common.util.concurrent.Futures$4.run(Futures.java:1172)
~[guava-16.0.jar:na]
at
com.google.common.util.concurrent.MoreExecutors$SameThreadExecutorService.ex
ecute(MoreExecutors.java:297) ~[guava-16.0.jar:na]
at
com.google.common.util.concurrent.ExecutionList.executeListener(ExecutionLis
t.java:156) ~[guava-16.0.jar:na]
at
com.google.common.util.concurrent.ExecutionList.execute(ExecutionList.java:1
45) ~[guava-16.0.jar:na]
at
com.google.common.util.concurrent.AbstractFuture.setException(AbstractFuture
.java:202) ~[guava-16.0.jar:na]
at
org.apache.cassandra.streaming.StreamResultFuture.maybeComplete(StreamResult
Future.java:209) ~[apache-cassandra-2.1.15.jar:2.1.15]
at
org.apache.cassandra.streaming.StreamResultFuture.handleSessionComplete(Stre
amResultFuture.java:185) ~[apache-cassandra-2.1.15.jar:2.1.15]
at
org.apache.cassandra.streaming.StreamSession.closeSession(StreamSession.java
:413) ~[apache-cassandra-2.1.15.jar:2.1.15]
at
org.apache.cassandra.streaming.StreamSession.maybeCompleted(StreamSession.ja
va:700) ~[apache-cassandra-2.1.15.jar:2.1.15]
at
org.apache.cassandra.streaming.StreamSession.taskCompleted(StreamSession.jav
a:661) ~[apache-cassandra-2.1.15.jar:2.1.15]
at
org.apache.cassandra.streaming.StreamReceiveTask$OnCompletionRunnable.run(St
reamReceiveTask.java:179) ~[apache-cassandra-2.1.15.jar:2.1.15]
at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
~[na:1.8.0_112]
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
~[na:1.8.0_112]
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:11
42) ~[na:1.8.0_112]
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:6
17) ~[na:1.8.0_112]
at java.lang.Thread.run(Thread.java:745) ~[na:1.8.0_112]
WARN [StorageServiceShutdownHook] 2017-08-12 23:54:51,582
Gossiper.java:1462 - No local state or state is in silent shutdown, not
announcing shutdown
INFO [StorageServiceShutdownHook] 2017-08-12 23:54:51,582
MessagingService.java:734 - Waiting for messaging service to quiesce
INFO [ACCEPT-/10.40.17.114 <http://10.40.17.114> ] 2017-08-12 23:54:51,583
MessagingService.java:1020 - MessagingService has terminated the accept()
thread
And I got this on this same node when it was bootstrapping, I ran 'nodetool
netstats' just before it shutdown:
Receiving 377 files, 161928296443 bytes total. Already received 377
files, 161928296443 bytes total
TPStats on host that was streaming the data to this node:
Pool Name Active Pending Completed Blocked All
time blocked
MutationStage 1 1 4488289014 0
0
ReadStage 0 0 24486526 0
0
RequestResponseStage 0 0 3038847374
<tel:(303)%20884-7374> 0 0
ReadRepairStage 0 0 1601576 0
0
CounterMutationStage 0 0 68403 0
0
MiscStage 0 0 0 0
0
AntiEntropySessions 0 0 0 0
0
HintedHandoff 0 0 18 0
0
GossipStage 0 0 2786892 0
0
CacheCleanupExecutor 0 0 0 0
0
InternalResponseStage 0 0 61115 0
0
CommitLogArchiver 0 0 0 0
0
CompactionExecutor 4 83 304167 0
0
ValidationExecutor 0 0 78249 0
0
MigrationStage 0 0 94201 0
0
AntiEntropyStage 0 0 160505 0
0
PendingRangeCalculator 0 0 30 0
0
Sampler 0 0 0 0
0
MemtableFlushWriter 0 0 71270 0
0
MemtablePostFlush 0 0 175209 0
0
MemtableReclaimMemory 0 0 81222 0
0
Native-Transport-Requests 2 0 1983565628 0
9405444
Message type Dropped
READ 218
RANGE_SLICE 15
_TRACE 0
MUTATION 2949001
COUNTER_MUTATION 0
BINARY 0
REQUEST_RESPONSE 0
PAGED_RANGE 0
READ_REPAIR 8571
I can get a jstack if needed.
>
>> >
>> > Rather than troubleshoot this further, what I was thinking about doing was:
>> > - drop the replication factor on our keyspace to two
>
> Repair before you do this, or you'll lose your consistency guarantees
Given the load on the 2 nodes in rack C I'm hoping a repair will succeed.
>
>> > - hopefully this would reduce load on these two remaining nodes
>
> It should, racks awareness guarantees on replica per rack if rf==num racks, so
> right now those 2 c machines have 2.5x as much data as the others. This will
> drop that requirement and drop the load significantly
>
>> > - run repairs/cleanup across the cluster
>> > - then shoot these two nodes in the 'c' rack
>
> Why shoot the c instances? Why not drop RF and then add 2 more C instances,
> then increase RF back to 3, run repair, then Decom the extra instances in a
> and b?
>
>
Fair point. I was considering staying at RF two but I think with your
points below, I should reconsider.
>> > - run repairs/cleanup across the cluster
>> >
>> > Would this work with minimal/no disruption?
>
> The big risk of running rf=2 is that quorum==all - any gc pause or node
> restarting will make you lose HA or strong consistency guarantees.
>
>> > Should I update their "rack" before hand or after ?
>
> You can't change a node's rack once it's in the cluster, it SHOULD refuse to
> start if you do that
>
Got it.
>> > What else am I not thinking about?
>> >
>> > My main goal atm is to get back to where the cluster is in a clean
>> consistent state that allows nodes to properly bootstrap.
>> >
>> > Thanks for your help in advance.
>> > ---------------------------------------------------------------------
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>> > For additional commands, e-mail: user-h...@cassandra.apache.org
>> >
>
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