Index: src/docbkx/performance.xml =================================================================== --- src/docbkx/performance.xml (revision 1245192) +++ src/docbkx/performance.xml (working copy) @@ -188,7 +188,12 @@ - +
+ ZooKeeper + See for information on configuring ZooKeeper, and see the part + about having a dedicated disk. + +
Schema Design Index: src/docbkx/configuration.xml =================================================================== --- src/docbkx/configuration.xml (revision 1245192) +++ src/docbkx/configuration.xml (working copy) @@ -659,9 +659,16 @@ only but in production it is recommended that you run a ZooKeeper ensemble of 3, 5 or 7 machines; the more members an ensemble has, the more tolerant the ensemble is of host - failures. Also, run an odd number of machines. There can be no - quorum if the number of members is an even number. Give each - ZooKeeper server around 1GB of RAM, and if possible, its own + failures. Also, run an odd number of machines. In ZooKeeper, + an even number of peers is supported, but it is normally not used + because an even sized ensemble requires, proportionally, more peers + to form a quorum than an odd sized ensemble requires. For example, an + ensemble with 4 peers requires 3 to form a quorum, while an ensemble with + 5 also requires 3 to form a quorum. Thus, an ensemble of 5 allows 2 peers to + fail, and thus is more fault tolerant than the ensemble of 4, which allows + only 1 down peer. + + Give each ZooKeeper server around 1GB of RAM, and if possible, its own dedicated disk (A dedicated disk is the best thing you can do to ensure a performant ZooKeeper ensemble). For very heavily loaded clusters, run ZooKeeper servers on separate machines