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From Apache Wiki <wikidi...@apache.org>
Subject [Cassandra Wiki] Update of "StorageConfiguration" by JonHermes
Date Fri, 08 Oct 2010 23:21:37 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 JonHermes.
http://wiki.apache.org/cassandra/StorageConfiguration?action=diff&rev1=46&rev2=47

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

  
  The name of this cluster.  This is mainly used to prevent machines in one logical cluster
from joining another.
  
-  * '''commitlog_directory and data_file_directories'''
+  * '''commitlog_directory''' and '''data_file_directories''' and '''saved_caches_directory'''
  
- Be sure to seperate your commitlog and data disks, as commitlog performance is reliant on
its append-only nature, and seeking to random data at the same time will damage write speed.
+ Be sure to seperate your commitlog and data disks, as commitlog performance is reliant on
its append-only nature, and seeking to random data at the same time will damage write speed.
The saved caches directory holds the saved caches of the column families. See '''key/row_cache_save_period_in_seconds'''
for elucidation.
  
- Defaults are: '/var/lib/cassandra/commitlog' and '/var/lib/cassandra/data'.
+ Defaults are: '/var/lib/cassandra/commitlog', '/var/lib/cassandra/data', and '/var/lib/cassandra/saved_caches'
respectively.
  
   * '''concurrent_reads''' and '''concurrent_writes''', '''commitlog_sync''' and '''commitlog_sync_period_in_ms'''
  
@@ -172, +172 @@

  
  Defaults are: '200000' keys cached, and '0', disabled row cache.
  
+  * '''key_cache_save_period_in_seconds''' and '''row_cache_save_period_in_seconds'''
+ 
+ Determines how often Cassandra saves the cache to the '''saved_caches_directory'''. Saved
caches greatly improve cold-start speeds, and is relatively cheap in terms of I/O.
+ 
+ Defaults are: '3600' seconds (1 hour) between saves of the key cache, and '0' (disabled)
row cache saving.
+ 
   * '''min_compaction_threshold''' and '''max_compaction_threshold'''
  
  Previously in the CompactionManager, these values tune the size and frequency of minor compactions.
The min and max boundaries are the number of tables to attempt to merge together at once.
Raising the minimum will make minor compactions take more memory and run less often, lowering
the maximum will have the opposite effect.

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