1/30/2024 0 Comments Vip care plan by dom health![]() ![]() The ISCAgent can send data to mirror members that have been down or disconnected. Most importantly, the ISCAgent provides a means by which one failover member can obtain information about the other when normal communication between the two has been interrupted. Generally speaking, DR async mirror members are a form of geo-replication (or georeplication).Ī process called the ISCAgent runs on each mirror member’s host system, providing an additional means of communication between mirror members. A DR async member can belong to one mirror only, but you can configure as many as you want in a single mirror, up to the mirror member limit of 16. A promoted DR can also be useful in performing planned maintenance on or temporarily replacing a failover member. Disaster Recovery AsyncsĪ mirror can provide disaster recovery capability through a disaster recovery (DR) async member, which can be manually promoted to failover member and even become primary should both failover members become unavailable due to a disaster. See Configure Async Mirror Members for information about adding an async member to a mirror. It is up to the application running against the async member to guarantee consistent results for queries that span changing data.Īlso, an async member can be configured for disaster recovery (DR) of a single mirror. ![]() Since the data on an async member is continually asynchronously updated with changes from the mirrors to which it is connected, there is no guarantee of synchronization of updates and synchronization of results across queries on the async member. A mirror can even be configured with a single failover member to utilize async members without automatic failover. A single mirror can include up to 16 members, so you can configure a mirror with a failover pair and up to 14 async members of either type in any combination. There are two types of async member, disaster recovery and reporting. Async Mirror MembersĪsync members maintain asynchronous copies of mirrored databases. If a problem is detected on the primary and the backup is available to take over it will do so immediately, even if the problem on the primary might resolve on its own given enough time.īecause network latency between the failover members is an important factor in application performance, the relative physical locations of the failover members and the network connection between them should be chosen to minimize latency in the connection see Network Latency Considerations for more information. For this reason, primary and backup must be considered temporary designations only. The two failover members in a mirror are assumed to be coequal neither is preferred as primary. See Automatic Failover Mechanics for detailed information about the automatic failover process. When the primary InterSystems IRIS instance becomes unavailable, the backup takes over, providing uninterrupted access to the databases without risk of data loss. At any given time, one failover instance acts as primary, providing applications with access to the databases in the mirror, while the other acts as backup, maintaining synchronized copies of those databases in readiness to take over as primary. To enable automatic failover, the mirror must contain two failover members, physically independent systems each hosting an InterSystems IRIS instance. Two additional components support automatic failover from one failover member to the other: (Similarly, the InterSystems IRIS instance is sometimes referred to as a mirror member.) There are two types of mirror member: The system hosting an InterSystems IRIS instance configured as part of a mirror is called a mirror member. This topic describes the components and mechanics of mirroring and explains issues in mirror planning including network requirements, redirecting application connections following failover, and mirroring in a virtualized environment. A mirror can provide high availability through automatic failover, in which a failure of the InterSystems IRIS instance providing database access (or its host system) causes another instance to take over automatically and immediately.
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