exactly - ZK-107 allows fully automatic reconfiguration without any restarts (it adds this as an API command to zookeeper). We also have a mechanism to rebalance clients across the new set of servers.
Currently you can do a rolling restart to change the configuration, which is quite tricky to do correctly, but I believe that Jordan's Exhibitor tool simplifies the process. Alex On Mon, Apr 30, 2012 at 11:54 AM, Jordan Zimmerman <[email protected]> wrote: > Technically, ZK does not support it. However, there is a methodology for > reconfiguring and updated an ensemble. I believe ZK-107 will allow the > changes to be made without needing to restart/reconfigure the cluster. > > -JZ > > On 4/30/12 11:49 AM, "Mohammad Abdul-Amir (Shamma)" > <[email protected]> wrote: > >>Alex, >> >>It sounds like you are suggesting that zookeeper keeper does not support >>adding/removing servers non-dynamically. If so, this contradicts with the >>FAQ #6 that Jordan Zimmerman pointed out. >> >>On Sun, Apr 29, 2012 at 11:32 PM, Alexander Shraer >><[email protected]>wrote: >> >>> Hi Mohammad, >>> >>> Support for adding/removing servers as well as dynamic changes to >>> other parameters will be added as part of ZOOKEEPER-107, hopefully in >>> the 3.5.0 release. >>> >>> Thanks, >>> Alex >>> >>> On Thu, Apr 26, 2012 at 3:55 PM, Mohammad Abdul-Amir (Shamma) >>> <[email protected]> wrote: >>> > On Thu, Apr 26, 2012 at 2:48 PM, Jordan Zimmerman < >>> [email protected]>wrote: >>> > >>> >> See #6 in the FAQ: http://wiki.apache.org/hadoop/ZooKeeper/FAQ >>> >> >>> >> >>> > Okay, it seems that a zookeeper "upgrade" is possible according to >>>FAQ. >>> > >>> > Does removing/decommissioning a zookeeper server fall under the >>>notion of >>> > "upgrade" though? Does "upgrade" apply to any zookeeper config update? >>> > >>> > >>> >> Also, FYI, we recently open sourced a ZooKeeper supervisor app that >>> makes >>> >> these kinds of tasks simpler: >>> >> >>> >> https://github.com/Netflix/exhibitor >>> >> >>> >> -Jordan >>> >> >>> >> On 4/26/12 2:46 PM, "Mohammad Abdul-Amir (Shamma)" >>> >> <[email protected]> wrote: >>> >> >>> >> >Hello, >>> >> > >>> >> >I have been searching through the zookeeper documentation and the >>>web >>> for >>> >> >information about reconfiguring a zookeeper ensemble. More >>>precisely I >>> am >>> >> >interested in adding/removing zookeeper servers to/from a zookeeper >>> >> >ensemble. Unfortunately, I could not find much information around, >>> >> >therefore I am bringing up the issue on this list. >>> >> > >>> >> >My questions are: >>> >> > >>> >> >- Is there a safe procedure to add a zookeeper server to a zookeeper >>> >> >ensemble? >>> >> >- Is there a safe procedure to remove a zookeeper server from an >>> existing >>> >> >ensemble? >>> >> > >>> >> >Some posts I have read suggest that these operations are possible. >>>The >>> >> >described procedure is to rewrite a new zookeeper configuration to >>>all >>> >> >involved servers and to restart them. However, given that I could >>>not >>> find >>> >> >any information about how to carry out these two operations in >>> zookeeper's >>> >> >documentation makes me nervous about relying on the described >>> procedure. >>> >> > >>> >> >I would appreciate if anyone can point me to a different procedures >>>to >>> >> >carry out add/remove operations, or convince me that it is safe to >>>use >>> the >>> >> >procedure described above. Safety for me is two-fold: zookeeper >>> database >>> >> >can not get corrupted (unusable), and state updates can not get >>>lost. >>> >> > >>> >> >-- >>> >> >Mohammad Abdul-Amir (Shamma) >>> >> >>> >> >>> > >>> > >>> > -- >>> > Mohammad Abdul-Amir (Shamma) >>> >> >> >> >>-- >>Mohammad Abdul-Amir (Shamma) >
