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From Chip Salzenberg <c...@pobox.com>
Subject 0.7.0beta2 with 128G memory = bizarre tiny files. help?
Date Wed, 27 Oct 2010 09:17:59 GMT
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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