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From Michael Kjellman <mkjell...@barracuda.com>
Subject Re: persistent compaction issue (1.1.4 and 1.1.5)
Date Thu, 20 Sep 2012 05:44:19 GMT
After changing my ss_table_size as recommended my pending compactions across the cluster have
leveled off at 34808 but it isn't progressing after 24 hours at that level.

As I've already changed the most offending column families I think the only option I have
left is to remove the .json files from all of the column families and do another rolling restart...

Developing... Thanks for the help so far

On Sep 19, 2012, at 10:35 PM, "Віталій Тимчишин" <tivv00@gmail.com<mailto:tivv00@gmail.com>>
wrote:

I did see problems with schema agreement on 1.1.4, but they did go away after rolling restart
(BTW: it would be still good to check describe schema for unreachable). Same rolling restart
helped to force compactions after moving to Leveled compaction. If your compactions still
don't go, you can try removing *.json files from the data directory of the stopped node to
force moving all SSTables to level0.

Best regards, Vitalii Tymchyshyn

2012/9/19 Michael Kjellman <mkjellman@barracuda.com<mailto:mkjellman@barracuda.com>>
Potentially the pending compactions are a symptom and not the root
cause/problem.

When updating a 3rd column family with a larger sstable_size_in_mb it
looks like the schema may not be in a good state

[default@xxxx] UPDATE COLUMN FAMILY screenshots WITH
compaction_strategy=LeveledCompactionStrategy AND
compaction_strategy_options={sstable_size_in_mb: 200};
290cf619-57b0-3ad1-9ae3-e313290de9c9
Waiting for schema agreement...
Warning: unreachable nodes 10.8.30.102The schema has not settled in 10
seconds; further migrations are ill-advised until it does.
Versions are UNREACHABLE:[10.8.30.102],
290cf619-57b0-3ad1-9ae3-e313290de9c9:[10.8.30.15, 10.8.30.14, 10.8.30.13,
10.8.30.103, 10.8.30.104, 10.8.30.105, 10.8.30.106],
f1de54f5-8830-31a6-9cdd-aaa6220cccd1:[10.8.30.101]


However, tpstats looks good. And the schema changes eventually do get
applied on *all* the nodes (even the ones that seem to have different
schema versions). There are no communications issues between the nodes and
they are all in the same rack

root@xxxx:~# nodetool tpstats
Pool Name                    Active   Pending      Completed   Blocked
All time blocked
ReadStage                         0         0        1254592         0
            0
RequestResponseStage              0         0        9480827         0
            0
MutationStage                     0         0        8662263         0
            0
ReadRepairStage                   0         0         339158         0
            0
ReplicateOnWriteStage             0         0              0         0
            0
GossipStage                       0         0        1469197         0
            0
AntiEntropyStage                  0         0              0         0
            0
MigrationStage                    0         0           1808         0
            0
MemtablePostFlusher               0         0            248         0
            0
StreamStage                       0         0              0         0
            0
FlushWriter                       0         0            248         0
            4
MiscStage                         0         0              0         0
            0
commitlog_archiver                0         0              0         0
            0
InternalResponseStage             0         0           5286         0
            0
HintedHandoff                     0         0             21         0
            0

Message type           Dropped
RANGE_SLICE                  0
READ_REPAIR                  0
BINARY                       0
READ                         0
MUTATION                     0
REQUEST_RESPONSE             0

So I'm guessing maybe the different schema versions may be potentially
stopping compactions? Will compactions still happen if there are different
versions of the schema?





On 9/18/12 11:38 AM, "Michael Kjellman" <mkjellman@barracuda.com<mailto:mkjellman@barracuda.com>>
wrote:

>Thanks, I just modified the schema on the worse offending column family
>(as determined by the .json) from 10MB to 200MB.
>
>Should I kick off a compaction on this cf now/repair?/scrub?
>
>Thanks
>
>-michael
>
>From: Віталій Тимчишин <tivv00@gmail.com<mailto:tivv00@gmail.com><mailto:tivv00@gmail.com<mailto:tivv00@gmail.com>>>
>Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org><mailto:user@cassandra.apache.org<mailto:user@cassandra.apache.org>>"
><user@cassandra.apache.org<mailto:user@cassandra.apache.org><mailto:user@cassandra.apache.org<mailto:user@cassandra.apache.org>>>
>To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org><mailto:user@cassandra.apache.org<mailto:user@cassandra.apache.org>>"
><user@cassandra.apache.org<mailto:user@cassandra.apache.org><mailto:user@cassandra.apache.org<mailto:user@cassandra.apache.org>>>
>Subject: Re: persistent compaction issue (1.1.4 and 1.1.5)
>
>I've started to use LeveledCompaction some time ago and from my
>experience this indicates some SST on lower levels than they should be.
>The compaction is going, moving them up level by level, but total count
>does not change as new data goes in.
>The numbers are pretty high as for me. Such numbers mean a lot of files
>(over 100K in single directory) and a lot of thinking for compaction
>executor to decide what to compact next. I can see numbers like 5K-10K
>and still thing this is high number. If I were you, I'd increase
>sstable_size_in_mb 10-20 times it is now.
>
>2012/9/17 Michael Kjellman
><mkjellman@barracuda.com<mailto:mkjellman@barracuda.com><mailto:mkjellman@barracuda.com<mailto:mkjellman@barracuda.com>>>
>Hi All,
>
>I have an issue where each one of my nodes (currently all running at
>1.1.5) is reporting around 30,000 pending compactions. I understand that
>a pending compaction doesn't necessarily mean it is a scheduled task
>however I'm confused why this behavior is occurring. It is the same on
>all nodes, occasionally goes down 5k pending compaction tasks, and then
>returns to 25,000-35,000 compaction tasks pending.
>
>I have tried a repair operation/scrub operation on two of the nodes and
>while compactions initially happen the number of pending compactions does
>not decrease.
>
>Any ideas? Thanks for your time.
>
>Best,
>michael
>
>
>'Like' us on Facebook for exclusive content and other resources on all
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>
>
>
>
>
>
>--
>Best regards,
> Vitalii Tymchyshyn
>
>'Like' us on Facebook for exclusive content and other resources on all
>Barracuda Networks solutions.
>
>Visit http://barracudanetworks.com/facebook
>
>
>
>


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--
Best regards,
 Vitalii Tymchyshyn

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solutions.
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