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Replication of domains between Swarm clusters provides for disaster recovery and locality of access to content. Many replication strategies are supported by Swarm including single-direction roll-up, multi-master, and cascading topographies. This section focuses on the content replicated to host storage domains in multiple clusters.
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Domain |
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CreationRegardless of the replication strategy selected, it is crucial a domain, whether an administrative domain or a storage domain, is only created once. |
A different domain sharing the same name is created if a domain with the same name is created using an SCSP operation or with the initgateway command in multiple Swarm clusters. This leads to incorrect results if the different domains are ever replicated into the same cluster due to the name collision. Create a domain name one time and use a Replication Feed to copy it to other clusters.
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Gateway adminDomainDo not create the same domain in two clusters: always create it in the source cluster and then replicate it to the target. A Gateway must use an independent adminDomain, at least temporarily, if the Gateway is in front of the target cluster. (CLOUD-2785) |
Verify the administrative domain is available in the other cluster if intending to use a storage domain within a cluster other than the one in which it was initially created. To use a storage domain means client requests (read, write, delete) are performed in the cluster. Replication of the administrative domain is unnecessary if the storage domain is replicated to another cluster purely for Disaster Recovery (DR) and client requests are ever sent to it. The initgateway command must be used in one cluster and then use Replication Feeds to duplicate the administrative domain into all other clusters.
Required
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Permission
Swarm needs to perform a "GET /" request during replication to check the Swarm cluster name and version when replicating through Gateway.
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{
"Effect":"Allow",
"Sid":"Swarm Node Status",
"Principal":{
"anonymous":[
"*"
]
},
"Action":[
"GetObject"
],
"Resource":"/"
}, |
See Policy Document.
Example
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Replication
The following diagram shows three Swarm storage clusters, storage domains A1 and A2, and an administrative domain A. Domains A, A1, and A2 are all initially created in Cluster Alpha. Remote replication is then configured to mirror domains A and A1 to Cluster Bravo. Additionally, domains A and A2 are configured to mirror to Cluster Charlie.
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