If you can live with restarting your NN, you are living with downtime. I'd definitely recommend running your NN on a mirrored RAID so it doesn't get taken out by a single bad disk.
As you say, stop HBase first if you are the one restarting the NN (not a hardware failure). Then you won't lose data. > -----Original Message----- > From: Jack Levin [mailto:[email protected]] > Sent: Tuesday, October 05, 2010 11:31 PM > To: [email protected] > Subject: Re: stopping namenode and regionservers > > Many reasons... like broken disk, ram, any sort of hardware > malfunction, just plain failure of namenode for any reason. > Generally, I guess I should be stopping regionservers before namenode > restart, at least I won't generate unflushed data. > > -Jack > > On Tue, Oct 5, 2010 at 11:25 PM, Jonathan Gray <[email protected]> > wrote: > > Currently HBase cannot ride over an HDFS restart. > > > > Might be feasible in the future but not currently planned. Some of > the NameNode HA solutions might indirectly address this. > > > > Why is it that you need to restart your namenode? > > > >> -----Original Message----- > >> From: Jack Levin [mailto:[email protected]] > >> Sent: Tuesday, October 05, 2010 10:45 PM > >> To: [email protected] > >> Subject: stopping namenode and regionservers > >> > >> Hi, is it possible to tell regionservers not to die/stop when > namenode > >> is restarted? Every onces in a while I need to restart namenode, > and > >> it causes all regionservers pretty much to shutdown, and in many > cases > >> not cleanly, which causes long start up delays (hlog, etc). > >> > >> Thanks. > >> > >> -Jack > >
