And another extension on top of Kishore's question: do the reelections happen if the previously elected leader remains in the cluster? In other words, what events can trigger re-election and the corresponding temporary degradation of the service provided by Zookeeper?
Thank you, /Sergey On Tue, Jul 16, 2013 at 2:21 AM, kishore g <[email protected]> wrote: > Regarding #2. Is that really true that during leader election every machine > reloads snapshot data from disk? Any reason why this is needed unless it > really needs to truncate or undo conflicting transactions already applied? > > > On Mon, Jul 15, 2013 at 9:50 PM, Thawan Kooburat <[email protected]> wrote: > > > Max snapshot size: > > > > Here is my take on these issue, others feel free to add or correct. > > > > 1. Depends on how much RAM your machine has. Snapshot is should be less > > than the available RAM since everything is loaded into memory. > > 2. Depends on what is the availability guarantee that the client needs. > > If there is leader election, every machine need to reload the data from > > disk. So the quorum will be down for at least the same as snapshot > loading > > time. The session timeout on the client side should be at least longer > > than expected downtime during leader election. > > > > -- > > Thawan Kooburat > > > > > > > > > > > > On 7/15/13 8:46 PM, "Sergey Maslyakov" <[email protected]> wrote: > > > > >I have a couple of sizing questions to the users and developers. Hope, > you > > >don't mind answering those. > > > > > >What is the guideline for the maximum reasonable size of a DataTree > that a > > >single ZK server can manage? If ZK server writes out a snapshot of about > > >1GB in size, is it pushed beyond the limits or is it still manageable? > If > > >so, where is the critical threshold when ZK is really being abused? > > > > > >Similarly, how can I estimate the propagation delay of a change across > an > > >ensemble of three ZK servers? > > > > > > > > >Thank you, > > >/Sergey > > > > >
