As I wrote, you should upgrade to 0.18 branch in SVN. J-D
On Tue, Feb 24, 2009 at 11:04 AM, Michael Dagaev <[email protected]>wrote: > I do not if it was holding ROOT or META region. > It looks like requests may fail in Hbase 0.18 if a region server stops. > > Thanks, > M. > > On Tue, Feb 24, 2009 at 5:40 PM, Jean-Daniel Cryans <[email protected]> > wrote: > > Well this should not happen like that. Was the region server holding the > > ROOT or META region? If so, well that's a bug corrected in 0.19.0 and > > branch-0.18. I suggest you upgrade to that version if you don't want to > > break your MR jobs. > > > > J-D > > > > On Tue, Feb 24, 2009 at 10:33 AM, Michael Dagaev > > <[email protected]>wrote: > > > >> What I see now is that the client gets an exception (see below) once a > >> region servers stops: > >> > >> org.apache.hadoop.hbase.client.NoServerForRegionException: No server > >> address listed in .META. > >> ... > >> Caused by: org.apache.hadoop.hbase.client.RetriesExhaustedException: > >> Trying to contact region server <region server>:60020 for region > >> > >> I guess the exception occurred since the region server is down. Is it > >> correct? > >> > >> Thank you for your cooperation, > >> M. > >> > >> P. S. We are running version 0.18.1 > >> > >> On Tue, Feb 24, 2009 at 5:07 PM, Jean-Daniel Cryans < > [email protected]> > >> wrote: > >> > Correcting myself, no waiting time regards the time to figure the node > is > >> > dead. It will still have to fetch the region location in META. > >> > > >> > J-D > >> > > >> > > >> > On Tue, Feb 24, 2009 at 10:02 AM, Jean-Daniel Cryans < > >> [email protected]>wrote: > >> > > >> >> Well if a region server dies instead of being cleanly shut down, it > >> takes > >> >> in the worst case 180 seconds (a region server lease length) before > the > >> >> Master reassigns the regions. Clients trying to connect to that > server > >> will > >> >> take IIRC 10 seconds to figure the node is down then the time to > >> communicate > >> >> with ROOT and META is under 1 sec. If META wasn't updated yet, it > will > >> retry > >> >> all of that. > >> >> > >> >> In the next release (0.20.0), the master is notified by Zookeeper in > the > >> >> following seconds of a region server death and will proceed to > reassign > >> the > >> >> regions immediately. > >> >> > >> >> If the client don't have the region in cache and META is updated with > >> the > >> >> region server death, there will be no waiting time. > >> >> > >> >> J-D > >> >> > >> >> > >> >> On Tue, Feb 24, 2009 at 9:49 AM, Michael Dagaev < > >> [email protected]>wrote: > >> >> > >> >>> Thanks, now it is clear. > >> >>> > >> >>> However, if a region server is down, it takes a lot of time to retry > >> >>> first, > >> >>> to rescan the META region when the retries fail, rescan ROOT, etc. > to > >> >>> get eventually to another region server, which will handle the > request. > >> >>> Is it correct ? > >> >>> > >> >>> On Tue, Feb 24, 2009 at 4:36 PM, Jean-Daniel Cryans < > >> [email protected]> > >> >>> wrote: > >> >>> > This is why we have a META table, it holds the location info. See > >> >>> > http://wiki.apache.org/hadoop/Hbase/HbaseArchitecture#client > >> >>> > > >> >>> > J-D > >> >>> > > >> >>> > On Tue, Feb 24, 2009 at 9:28 AM, Michael Dagaev < > >> >>> [email protected]>wrote: > >> >>> > > >> >>> >> Thanks, Jean-Daniel. > >> >>> >> > >> >>> >> I did run hbase-daemon stop regionserver and start regionserver > >> >>> >> and saw the client retrying to connect to the restarted region > >> server. > >> >>> >> > >> >>> >> How does it know to connect to another region server ? Maybe it > >> stops > >> >>> >> retrying, asks master, and get another region server to connect > to. > >> >>> >> Is it correct ? > >> >>> >> > >> >>> >> Thank you for your cooperation, > >> >>> >> M. > >> >>> >> > >> >>> >> On Tue, Feb 24, 2009 at 3:56 PM, Jean-Daniel Cryans < > >> >>> [email protected]> > >> >>> >> wrote: > >> >>> >> > Michael, > >> >>> >> > > >> >>> >> > Regards stopping those nodes, do it using > >> hadoop-daemon/hbase-daemon > >> >>> to > >> >>> >> stop > >> >>> >> > them cleanly. Requests from the clients will not "fail", they > will > >> >>> simply > >> >>> >> be > >> >>> >> > told to look elsewhere for the regions they have in cache. > Unless > >> you > >> >>> >> only > >> >>> >> > have 1 region server... > >> >>> >> > > >> >>> >> > Regards starting the nodes, apart from the usual > >> >>> >> hadoop-daemon/hbase-daemon, > >> >>> >> > no. > >> >>> >> > > >> >>> >> > J-D > >> >>> >> > > >> >>> >> > On Tue, Feb 24, 2009 at 8:50 AM, Michael Dagaev < > >> >>> >> [email protected]>wrote: > >> >>> >> > > >> >>> >> >> Hi, all > >> >>> >> >> > >> >>> >> >> As I understand, I can stop a region server and a data > node > >> in a > >> >>> >> >> cluster > >> >>> >> >> "semi-transparently" for clients, i. e. the requests handled > by > >> the > >> >>> >> >> region server > >> >>> >> >> at that time will fail, but cluster will be working. > >> >>> >> >> > >> >>> >> >> If I start the data node and region server I do not have to > do > >> >>> anything > >> >>> >> to > >> >>> >> >> make > >> >>> >> >> them work. > >> >>> >> >> > >> >>> >> >> Is it correct ? > >> >>> >> >> > >> >>> >> >> Thank you for your cooperation, > >> >>> >> >> M. > >> >>> >> >> > >> >>> >> > > >> >>> >> > >> >>> > > >> >>> > >> >> > >> >> > >> > > >> > > >
