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The purpose of this article is to provide Solution Engineers with an understanding of how VMware's VMotion works and answers to some of the common questions related to using VMware's VMotion with Appian.
VMware VMotion enables the live migration of running virtual machines from one physical server to another with zero downtime, continuous service availability, and complete transaction integrity. It is transparent to users.
VMotion lets you:
Appian does not recommend using VMotion because VMware's VMotion capability has been known to cause corruption inside Zookeeper, which can lead to site unavailability. Appian recommends disabling VMotion for any VMware severs that host Zookeeper. If the customer requests more detail regarding the corruption and what to watch out for, Engineering has provided us with the following:
"Zookeeper is very sensitive to latency. This is by design, since Zookeeper is in charge of coordinating state across the cluster. VMotion's migration process creates enough of a communications gap between the Zookeeper instances that they think a failure has occurred. Ephemeral data inside Zookeeper can be lost and if multiple Zookeeper nodes are migrated at the same time then they can lose quorum, which will cause that data to be lost. In addition, this blip in the Zookeeper cluster will almost assuredly cause Kafka/Service Manager to engage failover mechanism."
This article applies to Appian 17.3 and later.
Last Reviewed: November 2018