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From Apache Wiki <wikidi...@apache.org>
Subject [Cassandra Wiki] Update of "Operations" by JonathanEllis
Date Mon, 02 Aug 2010 13:36:52 GMT
Dear Wiki user,

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

The "Operations" page has been changed by JonathanEllis.
http://wiki.apache.org/cassandra/Operations?action=diff&rev1=57&rev2=58

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   1. Anti-Entropy: when `nodetool repair` is run, Cassandra computes a Merkle tree of the
data on that node, and compares it with the versions on other replicas, to catch any out of
sync data that hasn't been read recently.  This is intended to be run infrequently (e.g.,
weekly) since computing the Merkle tree is relatively expensive in disk i/o and CPU, since
it scans ALL the data on the machine (but it is is very network efficient).  
  
  Running `nodetool repair`:
- Like all nodetool operations, repair is non-blocking; it sends the command to the given
node, but does not wait for the repair to actually finish.  You can tell that repair is finished
when (a) there are no active or pending tasks in the CompactionManager, and after that when
(b) there are no active or pending tasks on AE-SERVICE-STAGE.
+ Like all nodetool operations, repair is non-blocking; it sends the command to the given
node, but does not wait for the repair to actually finish.  You can tell that repair is finished
when (a) there are no active or pending tasks in the CompactionManager, and after that when
(b) there are no active or pending tasks on o.a.c.concurrent.AE-SERVICE-STAGE, or o.a.c.service.StreamingService.
  
  Repair should be run against one machine at a time.  (This limitation will be fixed in 0.7.)
  

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