- Notes, cautions, and warnings
- Preface
- Introducing metro node
- Metro node use cases
- Features in metro node
- Integrity and resiliency
- Software and upgrade
This section describes how metro node Metro HA with cross-connect rides through failures of hosts, storage arrays, clusters, metro node Witness, and the inter-cluster link.
If hosts at one site fail, then VMware HA restarts the virtual machines on the surviving hosts. Since surviving hosts are connected to the same datastore, VMware can restart the virtual machines on any of the surviving hosts.
If a metro node cluster fails:
If one or more storage arrays at one site fail:
If metro node Witness fails or becomes unreachable (link outage):
If the inter-cluster link fails:
The following table summarizes how metro node HA with cross-connect manages failures.
Failure description | Failure handling |
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Host failure (Site 1) | VMware HA software automatically restarts the affected applications at Site 2. |
Metro node cluster failure (Site 1) | Metro node Witness detects the failure and enables all volumes on the surviving cluster. |
Inter-cluster link failure |
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Storage array failure | Applications are unaffected. Metro node dynamically redirects I/O to the mirrored copy on the surviving array.
NOTE This example assumes that all distributed volumes are also mirrored on the local cluster. If not, then the application remains available because the data can be fetched or sent from or to the remote cluster. However, each read/write operation now incurs a performance cost.
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Failure of metro node Witness | Both clusters call home. As long as both clusters continue to operate and there is no inter-cluster link partition, applications are unaffected.
CAUTION If either cluster fails or if there is an inter-cluster link partition, the system is at a risk of data unavailability. If the metro node Witness outage is expected to be long, disable the metro node Witness functionality to prevent the possible data unavailability.
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