any machine put in the conf/masters file becomes a secondary namenode. At some point there was confusion on the safety of more than one machine, which I believe was settled, as many are safe.
The secondary namenode takes a snapshot at 5 minute (configurable) intervals, rebuilds the fsimage and sends that back to the namenode. There is some performance advantage of having it on the local machine, and some safety advantage of having it on an alternate machine. Could someone who remembers speak up on the single vrs multiple secondary namenodes? On Thu, May 14, 2009 at 6:07 AM, David Ritch <david.ri...@gmail.com> wrote: > First of all, the secondary namenode is not a what you might think a > secondary is - it's not failover device. It does make a copy of the > filesystem metadata periodically, and it integrates the edits into the > image. It does *not* provide failover. > > Second, you specify its IP address in hadoop-site.xml. This is where you > can override the defaults set in hadoop-default.xml. > > dbr > > On Thu, May 14, 2009 at 9:03 AM, Rakhi Khatwani <rakhi.khatw...@gmail.com > >wrote: > > > Hi, > > I wanna set up a cluster of 5 nodes in such a way that > > node1 - master > > node2 - secondary namenode > > node3 - slave > > node4 - slave > > node5 - slave > > > > > > How do we go about that? > > there is no property in hadoop-env where i can set the ip-address for > > secondary name node. > > > > if i set node-1 and node-2 in masters, and when we start dfs, in both the > > m/cs, the namenode n secondary namenode processes r present. but i think > > only node1 is active. > > n my namenode fail over operation fails. > > > > ny suggesstions? > > > > Regards, > > Rakhi > > > -- Alpha Chapters of my book on Hadoop are available http://www.apress.com/book/view/9781430219422 www.prohadoopbook.com a community for Hadoop Professionals
