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Data Loss scenarios

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Fri, 02/10/2012 - 14:49
davidkerr
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Joined: 02/10/2012
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Hello,

Sorry, if this is a common question, i did search, but only found Membase specific answers,
and I'm primarily interested in 2.0, so I'm just making sure nothing has changed.

I'm evaluating CouchBase as a replacement to our traditional RDBMs. One of the criteria I'm looking at is "potential for data loss"

Am I correct in this statement:

If configured for Async Replication there is potential for data loss if a node fails.
(i.e., a node fails prior to being stored to disk, or to being replicated to the replica set)

If configured for Sync Replication there is potential for data loss if multiple nodes fail.
(In the event that a both nodes containing the in-memory data fail before either of them writes
to disk)

(Note, I understand the risk of either is fairly small, but I'm recording potential and not
probability)

The reason I ask is because I've read that Membase is ACID within a single node, and that doesn't
seem to match with the above assertion.

Thanks!

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Mon, 03/19/2012 - 00:09
ingenthr
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Joined: 03/16/2010
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Persistence and replication are both asynchronous in the default case, so while Couchbase Server always tries to do things as fast as possible, there is risk of data loss in those asynch windows.

There is not currently an option for synchronous replication. There is an upcoming feature named OBSERVE which will give you more control over this at both the persistence and replication level.

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