I have created HBASE-8269 for this documentation update.
2013/4/4 Jean-Marc Spaggiari <[email protected]>: >>Isn't this done via pipelining anyway? > Yes, it's the way it's done. > >>So there's no notion of ordering with respect 1st, 2nd, and 3rd block, either >>all writes go through the pipeline or none are. > Still correct. > >> When the write request returns to the client there will be a local copy, a >> copy on another machine in the same, and a copy on a machine in a different >> rack, who cares about the ordering inside the pipeline? > Not necessary. There might not be any additional copy on a different > machine on the same rack. BUT.. As you said, who cares ;) As long as > we have the local copy and some replicas. > > I have updated the documentation already. I will open the JIRA and > submit. I have also added subsequent replicas in case replication > factor is > 3. > > JM > > 2013/4/4 lars hofhansl <[email protected]>: >> Isn't this done via pipelining anyway? >> So there's no notion of ordering with respect 1st, 2nd, and 3rd block, >> either all writes go through the pipeline or none are. >> >> When the write request returns to the client there will be a local copy, a >> copy on another machine in the same, and a copy on a machine in a different >> rack, who cares about the ordering inside the pipeline? >> >> >> Seems it would also be inefficient to pipeline from the local rack to >> another another one and then in the same pipeline back into the local rack >> (more load on the switch connecting the racks with no benefit). >> >> I'll double check. >> >> >> -- Lars >> >> >> >> ________________________________ >> From: Jean-Marc Spaggiari <[email protected]> >> To: [email protected] >> Sent: Thursday, April 4, 2013 8:25 AM >> Subject: Re: confused info about region-regionserver locality > > >> >> Hi, >> >> I think you're right and documentation need to be updated. >> >> The 3rd replica is written on a random node in the same rack as the >> 2nd replica. I will double check. Can you please open a JIRA so this >> is updated? >> >> JM >> >> 2013/4/4 KIM JUN YOUNG <[email protected]>: >>> Hi All. >>> >>> There is confused understanding about region-regionser locality. >>> >>> from the current document , >>> >>> http://hbase.apache.org/book/regions.arch.html >>> 9.7.3. Region-RegionServer Locality >>> Over time, Region-RegionServer locality is achieved via HDFS block >>> replication. The HDFS client does the following by default when choosing >>> locations to write replicas: >>> >>> First replica is written to local node >>> Second replica is written to another node in same rack >>> Third replica is written to a node in another rack (if sufficient nodes) >>> >>> >>> but, my understanding is different >>> HDFS write blocks for replica >>> >>> first, local node >>> second, another node in another rack >>> third, random another node in same rack >>> >>> need to be changed? or am I missing something?
