cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Maki Watanabe <>
Subject Re: sync commitlog in batch mode lose data
Date Tue, 31 May 2011 08:30:50 GMT
How much replication factor did you set for the keyspace?
If the RF is 2, your data should be replicated to both of nodes. If
the RF is 1, you will lose the half of data when the node A is down.


2011/5/31 Preston Chang <>:
> Hi,
> I have a cluster with two nodes (node A and node B) and make a test as
> follows:
> 1). set commitlog sync in batch mode and the sync batch window in 0 ms
> 2). one client wrote random keys in infinite loop with consistency level
> QUORUM and record the keys in file after the insert() method return normally
> 3). unplug one server (node A) power cord
> 4). restart the server and cassandra service
> 5). read the key list generated in step 2) with consistency level ONE
> I thought the result of test is all the key in list can be read normally,
> but actually there are some NotFound keys.
> My question is why there are NotFound keys. In my opinion server would not
> ack the client before finishing syncing the commitlog if I set commitlog
> sync in batch mode and the sync batch window in 0 ms. So if the insert()
> method return normally it means the mutation had been written in commitlog
> and the commitlog had been synced to the disk. Am I right?
> My Cassandra version is 0.7.3.
> Thanks for your help very much.
> --
> by Preston Chang


View raw message