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From "Jonathan Ellis (JIRA)" <>
Subject [jira] Commented: (CASSANDRA-195) Improve bootstrap algorithm
Date Mon, 03 Aug 2009 23:17:14 GMT


Jonathan Ellis commented on CASSANDRA-195:

Some implementation-level details:
 - add a "bootstrap mode" to cassandra startup.  When started with bootstrap mode, it would
wait a minute or two to get the node/token map, then tell the node whose range it is moving
into to send over the data.  When that is done it will start answering replies.  We don't
want the node to behave like a normal node at all until then, so we should take the bootstrap
command out of nodeprobe.  If it can't complete bootstrap, it should abort.  (Bootstrap by
definition requires operator intervention so this is fair.)
 - the node D should continue receiving writes for the range in question during this process,
and forward them to the bootstrapping node Z
 - if anticompact splits existing SSTables (removing the old "big" one) and leaves both live
during this process, we will save doing an extra scan of the old SSTable for Cleanup later
in the old model of copying out the to-move data to a special directory.

> Improve bootstrap algorithm
> ---------------------------
>                 Key: CASSANDRA-195
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>         Environment: all
>            Reporter: Sandeep Tata
>             Fix For: 0.5
> When you add a node to an existing cluster and the map gets updated, the new node may
respond to read requests by saying it doesn't have any of the data until it gets the data
from the node(s) the previously owned this range (the load-balancing code, when working properly
can take care of this). While this behaviour is compatible with eventual consistency, it would
be much friendlier for the new node not to "surface" in the EndPoint maps for reads until
it has transferred the data over from the old nodes.

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