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From Chip Salzenberg <c...@pobox.com>
Subject Re: 0.7.0beta2 with 128G memory = bizarre tiny files. help?
Date Wed, 27 Oct 2010 17:58:28 GMT
Are these values available in JMX?  If so, which ones are they?  I'd
prefer not to possibly destroy the evidence by upgrading.

On 10/27/2010 6:50 AM, Jonathan Ellis wrote:
> Connect with the cli and run "show keyspaces."  It sounds like
> Cassandra somehow picked ludicrously low memtable thresholds.  There
> will be a line like
>
>       Memtable thresholds: 0.2953125/63/60
>
> This may not be in the b2 cli, in which case you will need to upgrade
> to the nightly from
> http://hudson.zones.apache.org/hudson/job/Cassandra/lastSuccessfulBuild/artifact/cassandra/build/
> (essentially the same as rc1 being voted on).
>
> On Wed, Oct 27, 2010 at 4:17 AM, Chip Salzenberg <chip@pobox.com> wrote:
>> I recently tested 0.7.0beta2 with good results on a reasonably powerful
>> machine: 8 Xeon cores (16 if you count hyperthreads), 64G memory, and
>> some nice HP RAID.  So far so good.  But when I took the same config and
>> moved it to a basically identical box with 128G of memory, cassandra
>> started responding to writes by creating a plethora of teeny tiny
>> sstables -- something it had not done before.  For example:
>>
>>  INFO [FLUSH-WRITER-POOL:1] 2010-10-27 01:53:27,881 Memtable.java (line
>> 150) Writing Memtable-Standard1@950886315(651 bytes, 18 operations)
>>  INFO [MUTATION_STAGE:8] 2010-10-27 01:53:27,882 ColumnFamilyStore.java
>> (line 459) switching in a fresh Memtable for Standard1 at
>> CommitLogContext(file='/var/lib/cassandra/commitlog/_chip/CommitLog-1288169534132.log',
>> position=27598)
>>  INFO [MUTATION_STAGE:8] 2010-10-27 01:53:27,883 ColumnFamilyStore.java
>> (line 771) Enqueuing flush of Memtable-Standard1@1383310803(384 bytes,
>> 10 operations)
>>  INFO [FLUSH-WRITER-POOL:1] 2010-10-27 01:53:27,902 Memtable.java (line
>> 157) Completed flushing
>> /var/lib/cassandra/data/_chip/Keyspace1/Standard1-e-7-Data.db
>>  INFO [FLUSH-WRITER-POOL:1] 2010-10-27 01:53:27,903 Memtable.java (line
>> 150) Writing Memtable-Standard1@996627145(360 bytes, 10 operations)
>>  INFO [MUTATION_STAGE:3] 2010-10-27 01:53:27,927 ColumnFamilyStore.java
>> (line 459) switching in a fresh Memtable for Standard1 at
>> CommitLogContext(file='/var/lib/cassandra/commitlog/_chip/CommitLog-1288169534132.log',
>> position=31446)
>>  INFO [MUTATION_STAGE:3] 2010-10-27 01:53:27,927 ColumnFamilyStore.java
>> (line 771) Enqueuing flush of Memtable-Standard1@1909350010(957 bytes,
>> 26 operations)
>>  INFO [FLUSH-WRITER-POOL:1] 2010-10-27 01:53:27,932 Memtable.java (line
>> 157) Completed flushing
>> /var/lib/cassandra/data/_chip/Keyspace1/Standard1-e-8-Data.db
>>  INFO [FLUSH-WRITER-POOL:1] 2010-10-27 01:53:27,933 Memtable.java (line
>> 150) Writing Memtable-Standard1@1383310803(384 bytes, 10 operations)
>>  INFO [CompactionExecutor:1] 2010-10-27 01:53:27,934
>> CompactionManager.java (line 233) Compacting
>> [org.apache.cassandra.io.sstable.SSTableReader(path='/var/lib/cassandra/data/_chip/Keyspace1/Standard1-e-5-Data.db'),org.apache.cassandra.io.sstable.SSTableReader(path='/var/lib/cassandra/data/_chip/Keyspace1/Standard1-e-6-Data.db'),org.apache.cassandra.io.sstable.SSTableReader(path='/var/lib/cassandra/data/_chip/Keyspace1/Standard1-e-7-Data.db'),org.apache.cassandra.io.sstable.SSTableReader(path='/var/lib/cassandra/data/_chip/Keyspace1/Standard1-e-8-Data.db')]
>>  INFO [MUTATION_STAGE:17] 2010-10-27 01:53:27,936 ColumnFamilyStore.java
>> (line 459) switching in a fresh Memtable for Standard1 at
>> CommitLogContext(file='/var/lib/cassandra/commitlog/_chip/CommitLog-1288169534132.log',
>> position=33074)
>>  INFO [MUTATION_STAGE:17] 2010-10-27 01:53:27,936 ColumnFamilyStore.java
>> (line 771) Enqueuing flush of Memtable-Standard1@595066677(396 bytes, 11
>> operations)
>>  INFO [FLUSH-WRITER-POOL:1] 2010-10-27 01:53:28,037 Memtable.java (line
>> 157) Completed flushing
>> /var/lib/cassandra/data/_chip/Keyspace1/Standard1-e-9-Data.db
>>
>> I tried lowering the available memory reported by bin/cassandra:
>>
>>            system_memory_in_mb=`free -m | awk '/Mem:/ {print $2}'`
>>            [ "$system_memory_in_mb" -gt 65536 ] &&
>> system_memory_in_mb=65536      #<<<< new
>>
>> Didn't help.  I also tried maually setting the max memtable sizes:
>>
>>    binary_memtable_throughput_in_mb: 512
>>    memtable_throughput_in_mb: 4096
>>
>> Didn't help.
>>
>> Help?
>>
>
>

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