ClustrixDB Xpand allows clusters to be deployed across multiple zones to provide fault tolerance during unplanned zone failure. A zone in ClustrixDB Xpand is grouping of nodes, such as AWS Availability Zones within the same Region, different server racks, different network switches, different power sources, or even separate servers in different data centers. ClustrixDB Xpand requires that network latency between zones not exceed 2ms.
|Table of Contents|
When ClustrixDB Xpand is configured for zones, the Rebalancer becomes zone-aware and ensures replicas are placed in different zones. Additionally, Paxos accepters are distributed across multiple zones. The result is that ClustrixDB Xpand is fault tolerant in the face of unexpected zone failure, regardless of how many nodes are in the zone.
Use of zones with ClustrixDB Xpand has the following prerequisites:
There must be the same number of nodes in each zone. Clustrix Xpand recommends deploying a 9 node cluster across 3 zones.
To configure zones, use ALTER CLUSTER ZONE to assign nodes to a zone. Zone ids must be greater than 0 and there must be an equal number of nodes in each zone. For example, a 9 node cluster deployed across 3 zones should have 3 nodes each in zones 1, 2, and 3.
Clustrix Xpand recommends provisioning enough free disk space to reprotect the data after a zone failure. See Allocating Disk Space for Fault Tolerance and Availability .
Clustrix Xpand currently supports a minimum of 3 and a maximum of 5 zones.
For further information, see Understanding Fault Tolerance in ClustrixDBXpand.