-Re: Does Hadoop 1.0.4 provide a durable sync for HBase-0.94.6?
Stack 2013-05-28, 16:53
On Tue, May 28, 2013 at 7:09 AM, jingguo yao <[EMAIL PROTECTED]> wrote:
> Section 2.1.3 says that Hadoop 1.0.4 works with HBase-0.94.x . And
> Section 18.104.22.168 says that 1.0.4 has a working durable sync. But when I
> check the source code of DFSClient.DFSOutputStream's sync method, I
> finds the following javadoc:
> * All data is written out to datanodes. It is not guaranteed
> * that data has been flushed to persistent store on the
> * datanode. Block allocations are persisted on namenode.
> So it seems that sync does not support a durable sync. It contradicts
> with .
> Can anybody help me on this confusion? Thanks.
This issue is probably the best source for the state of sync in hbase (and
In short, the refguide is misleading -- let me fix -- as 1.0.4 indeed has a
sync but it is just a sync to the memory of three datanodes, not a true
fsync out to disk. The above cited issue is tracking issues that our Lars
and other have contributed to HDFS to add fsync support.