I have master also serving as regionserver. I'll run ZK also on 3 of the regionservers. I don't have too much data (few TBs only), so I guess it would be fine?
On Thu, Dec 9, 2010 at 12:44 AM, Ted Dunning <tdunn...@maprtech.com> wrote: > Ahh... that is very much at the other end of the spectrum from what I am > used to. > > Yes. It would not be good to run ZK on a system where the disk is > essentially unavailable for > significant amounts of time. > > On Wed, Dec 8, 2010 at 10:24 AM, Jean-Daniel Cryans <jdcry...@apache.org > >wrote: > > > Ted, > > > > Sorry, wrong choice of words, HBase will be unreliable. I'm referring > > to a situation where the session timeout is caused by a very slow > > quorum because, as I saw it happening before, the datanodes where > > pegging the disk(s) while being hammered by the region servers. > > > > J-D > > > > On Wed, Dec 8, 2010 at 10:20 AM, Ted Dunning <tdunn...@maprtech.com> > > wrote: > > > This is a bit misleading. ZK is always reliable regardless of disk > > latency. > > > All that happens on a busy disk is that > > > you get longer latency for ZK transactions. For a dedicated and > > > well-configured machine, you can have average > > > latency (including committing to disk) of about 7 ms. For a > > multi-purpose > > > busy machine, you may see latencies > > > of 300 ms. > > > > > > Neither case will cause unreliable operation. > > > > > > On Wed, Dec 8, 2010 at 10:14 AM, Jean-Daniel Cryans < > jdcry...@apache.org > > >wrote: > > > > > >> Basically, ZK simply needs the lowest latency to disk and network in > > >> order to work reliably. It's not CPU intensive, and it's only memory > > >> intensive if you are using tons of znodes (HBase doesn't). > > >> > > > > > >
