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 <[email protected]>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 <[email protected]> > 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 <[email protected] > >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). > >> > > >
