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From Apache Wiki <wikidi...@apache.org>
Subject [Cassandra Wiki] Update of "StorageConfiguration" by tuxracer69
Date Sat, 14 Nov 2009 14:33:45 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Cassandra Wiki" for change notification.

The "StorageConfiguration" page has been changed by tuxracer69.
http://wiki.apache.org/cassandra/StorageConfiguration?action=diff&rev1=3&rev2=4

--------------------------------------------------

  Unlike most systems, in Cassandra writes are faster than reads, so you can afford more of
those in parallel.  A good rule of thumb is 2 concurrent reads per processor core.  Increase
{{{ConcurrentWrites}}} to the number of clients writing at once if you enable {{{CommitLogSync
+ CommitLogSyncDelay}}}.
  
  {{{
- <ConcurrentReads>8</ConcurrentReads> <ConcurrentWrites>32</ConcurrentWrites>
+ <ConcurrentReads>8</ConcurrentReads> 
+ <ConcurrentWrites>32</ConcurrentWrites>
  }}}
  
  {{{CommitLogSync}}} may be either "periodic" or "batch."  When in batch mode, Cassandra
won't ack writes until the commit log has been fsynced to disk.  It will wait up to {{{CommitLogSyncBatchWindowInMS}}}
milliseconds for other writes, before performing the sync.
@@ -214, +215 @@

  Number of threads to run when flushing memtables to disk.  Set this to the number of disks
you physically have in your machine allocated for {{{DataDirectory * 2}}}.  If you are planning
to use the Binary Memtable, its recommended to increase the max threads to maintain a higher
quality of service while under load when normal memtables are flushing to disk.
  
  {{{
- <FlushMinThreads>1</FlushMinThreads> <FlushMaxThreads>1</FlushMaxThreads>
+ <FlushMinThreads>1</FlushMinThreads> 
+ <FlushMaxThreads>1</FlushMaxThreads>
  }}}
  
  The threshold size in megabytes the binary memtable must grow to, before it's submitted
for flushing to disk.

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