Disaster Tolerance and Recovery in a Serviceguard Cluster
Understanding Types of Disaster Tolerant Clusters
•Disk resynchronization is independent of CPU failure (that is, if the hosts at the primary site fail but the disk remains up, the disk knows it does not have to be resynchronized).
Differences Between Extended Distance Cluster and CLXThe major differences between an Extended Distance Cluster and a CLX cluster are:
•The methods used to replicate data between the storage devices in the two data centers. The two basic methods available for replicating data between the data centers for Linux clusters are either
•Data centers in an Extended Distance Cluster can span up to 100km, whereas the distance between data centers in a Metrocluster is defined by the shortest of the following distances:
—Maximum distance that guarantees a network latency of no more than 200ms
—Maximum distance supported by the data replication link
—Maximum supported distance for DWDM as stated by the provider
•In an Extended Distance Cluster, there is no
It is possible for data to be updated on the disk system local to a server running a package without remote data being updated. This happens if the data link between sites is lost, usually as a precursor to a site going down. If that occurs and the site with the latest data then goes down, that data is lost. The period of time from the link lost to the site going down is called the "recovery point". An
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