I think I have figured out the problem or may be not. In order to simulate RegionServer failure my fellow programmer was killing the Regionserver by *kill -9 pid . *But when I used *kill pid* everything seems to be working fine. Obviously now region server is going down gracefully so there is no data loss.
I also checked it on hadoop 0.20.2(without append), HBase 0.20.5 version and found no data-loss in case of simple kill command. Now my next question is should it also work with *kill -9* command? FYI - I am using VMs. In my current setup I am using 3 VMs, 1 for Namenode and HBase Master and both 2 and 3 have Data node and region servers running on them. Thanks, Gagan On Thu, Sep 2, 2010 at 8:18 PM, Stack <[email protected]> wrote: > On Thu, Sep 2, 2010 at 3:34 AM, Gagandeep Singh > <[email protected]> wrote: > > Hi Daniel > > > > I have downloaded hadoop-0.20.2+320.tar.gz from this location > > http://archive.cloudera.com/cdh/3/ > > > That looks right, yes. > > > And also changed the *dfs.support.append* flag to *true* in your * > > hdfs-site.xml* as mentioned here > > http://wiki.apache.org/hadoop/Hbase/HdfsSyncSupport. > > > > That sounds right too. As Ted suggests, you put it in to all configs > (though I believe it enabled by default on that branch -- in the UI > you'd see a warning if it was NOT enabled). > > > But data loss is still happening. Am I using the right version? > > Is there any other settings that I need to make so that data gets flushed > to > > HDFS. > > > > It looks like you are doing the right thing. Can we see master log please? > > Thanks, > St.Ack > > > > Thanks, > > Gagan > > > > > > > > On Thu, Aug 26, 2010 at 11:57 PM, Jean-Daniel Cryans < > [email protected]>wrote: > > > >> That, or use CDH3b2. > >> > >> J-D > >> > >> On Thu, Aug 26, 2010 at 11:22 AM, Gagandeep Singh > >> <[email protected]> wrote: > >> > Thanks Daniel > >> > > >> > It means I have to checkout the code from branch and build it on my > local > >> > machine. > >> > > >> > Gagan > >> > > >> > > >> > On Thu, Aug 26, 2010 at 9:51 PM, Jean-Daniel Cryans < > [email protected] > >> >wrote: > >> > > >> >> Then I would expect some form of dataloss yes, because stock hadoop > >> >> 0.20 doesn't have any form of fsync so HBase doesn't know whether the > >> >> data made it to the datanodes when appending to the WAL. Please use > >> >> the 0.20-append hadoop branch with HBase 0.89 or cloudera's CDH3b2. > >> >> > >> >> J-D > >> >> > >> >> On Thu, Aug 26, 2010 at 7:22 AM, Gagandeep Singh > >> >> <[email protected]> wrote: > >> >> > HBase - 0.20.5 > >> >> > Hadoop - 0.20.2 > >> >> > > >> >> > Thanks, > >> >> > Gagan > >> >> > > >> >> > > >> >> > > >> >> > On Thu, Aug 26, 2010 at 7:11 PM, Jean-Daniel Cryans < > >> [email protected] > >> >> >wrote: > >> >> > > >> >> >> Hadoop and HBase version? > >> >> >> > >> >> >> J-D > >> >> >> > >> >> >> On Aug 26, 2010 5:36 AM, "Gagandeep Singh" < > >> [email protected]> > >> >> >> wrote: > >> >> >> > >> >> >> Hi Group, > >> >> >> > >> >> >> I am checking HBase/HDFS fail over. I am inserting 1M records from > my > >> >> HBase > >> >> >> client application. I am clubbing my Put operation such that 10 > >> records > >> >> get > >> >> >> added into the List<Put> and then I call the table.put(). I have > not > >> >> >> modified the default setting of Put operation which means all data > is > >> >> >> written in WAL and in case of server failure my data should not be > >> lost. > >> >> >> > >> >> >> But I noticed somewhat strange behavior, while adding records if I > >> kill > >> >> my > >> >> >> Region Server then my application waits till the time region data > is > >> >> moved > >> >> >> to another region. But I noticed while doing so all my data is > lost > >> and > >> >> my > >> >> >> table is emptied. > >> >> >> > >> >> >> Could you help me understand the behavior. Is there some kind of > >> Cache > >> >> also > >> >> >> involved while writing because of which my data is lost. > >> >> >> > >> >> >> > >> >> >> Thanks, > >> >> >> Gagan > >> >> >> > >> >> > > >> >> > >> > > >> > > >
