Home | About | Sematext search-lucene.com search-hadoop.com
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB
 Search Hadoop and all its subprojects:

Switch to Threaded View
HBase >> mail # user >> HBase failure scenarios


Copy link to this message
-
Re: HBase failure scenarios
yes,
when a write is successful to the WAL on the responsible region server,
in fact that means that the write was committed to 3 total DataNodes

--Send from my Sony mobile.
On Jun 11, 2013 8:40 AM, "Lucas Stanley" <[EMAIL PROTECTED]> wrote:

> Thanks Azuryy!
>
> So, when a write is successful to the WAL on the responsible region server,
> in fact that means that the write was committed to 3 total DataNodes,
> correct?
>
>
> On Mon, Jun 10, 2013 at 5:37 PM, Azuryy Yu <[EMAIL PROTECTED]> wrote:
>
> > yes. datanode write is pipeline. and only if pipeline writing finished,
> dn
> > return ok.
> >
> > --Send from my Sony mobile.
> > On Jun 11, 2013 8:27 AM, "Lucas Stanley" <[EMAIL PROTECTED]> wrote:
> >
> > > Hi,
> > >
> > > In the Strata 2013 training lectures, Jonathan Hsieh from Cloudera said
> > > something about HBase syncs which I'm trying to understand further.
> > >
> > > He said that HBase sync guarantees only that a write goes to the local
> > disk
> > > on the region server responsible for that region and in-memory copies
> go
> > on
> > > 2 other machines in the HBase cluster.
> > >
> > > But I thought that when the write goes to the WAL on the first region
> > > server, that the HDFS append would push that write to 3 machines total
> in
> > > the HDFS cluster. In order for the append write to the WAL to be
> > > successful, doesn't the DataNode on that machine have to pipeline the
> > write
> > > to 2 other DataNodes?
> > >
> > > I'm not sure what Jonathan was referring to when he said that 2
> in-memory
> > > copies go to other HBase machines? Even when the memstore on the first
> > > region server gets full, doesn't the flush to the HFile get written on
> 3
> > > HDFS nodes in total?
> > >
> >
>
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB