cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Apache Wiki <wikidi...@apache.org>
Subject [Cassandra Wiki] Update of "Operations" by JonathanEllis
Date Tue, 08 Dec 2009 23:00:54 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=4&rev2=5

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

  
  == Token selection ==
  
- Using a strong hash function means !RandomPartitioner keys will, on average, be evenly spread
across the Token space, but you can still have imbalances if your Tokens do not divide up
the range evenly, so you should specify InitialToken to your first nodes as `i * (2**127 /
N)` for i = 1 .. N.
+ Using a strong hash function means !RandomPartitioner keys will, on average, be evenly spread
across the Token space, but you can still have imbalances if your Tokens do not divide up
the range evenly, so you should specify !InitialToken to your first nodes as `i * (2**127
/ N)` for i = 1 .. N.
  
  With order preserving partioners, your key distribution will be application-dependent. 
You should still take your best guess at specifying initial tokens (guided by sampling actual
data, if possible), but you will be more dependent on active load balancing (see below) and/or
adding new nodes to hot spots.
  
@@ -70, +70 @@

  
  If a node goes down and comes back up, the ordinary repair mechanisms will be adequate to
deal with any inconsistent data.  If a node goes down entirely, you should be aware of the
following as well:
   1. Remove the old node from the ring first, or bring up a replacement node with the same
IP and Token as the old; otherwise, the old node will stay part of the ring in a "down" state,
which will degrade your replication factor for the affected Range
-   * If you don't know the Token of the old node, you can retrieve it from any of the other
nodes' `system` keyspace, ColumnFamily `LocationInfo`, key `L`.
+   * If you don't know the Token of the old node, you can retrieve it from any of the other
nodes' `system` keyspace, !ColumnFamily `LocationInfo`, key `L`.
   1. Removing the old node, then bootstrapping the new one, may be more performant than using
Anti-Entropy.  Testing needed.
    * Even brute-force rsyncing of data from the relevant replicas and running cleanup on
the replacement node may be more performant
  

Mime
View raw message