Cluster Management, Monitoring, and Troubleshooting
Cluster Management, Monitoring, and Troubleshooting
This domain tests day-two operations: capacity and health management, reading monitoring data, and diagnosing failed runs methodically rather than by guesswork.
Cluster operations
Adding a node extends capacity and performance; removing a node triggers a data rebalance so no data is lost - plan for the rebuild window. Health checks should precede upgrades, which can be orchestrated from Helios across clusters. Storage domains and views carry quotas, and capacity forecasting matters because deduplication ratios change as data ages. Support bundles and log collection are the standard artefacts for opening a case.
Monitoring
Helios provides cross-cluster dashboards, alerting, reports, and upgrade orchestration; the cluster UI provides per-job run details, snapshot inventories, and audit logs. Watch protection status against policy SLA, failed or missed runs, capacity trend, throughput, and replication lag. Note the distinction: alerts signal conditions needing action, while audit logs record who did what.
A troubleshooting method
- Establish scope - one VM, one source, one cluster, or all clusters.
- Open the failed run and read the error and task log rather than restarting blindly.
- Check connectivity and credentials to the source (expired service accounts are a common cause).
- Check cluster health - failed disks, node outages, or a cluster partition.
- Check the target: replication link, archive target credentials, free capacity.
- Correlate with recent changes - upgrades, network or MTU changes, policy edits.
Worked example
Every VM under one vCenter has failed nightly for two days, while another vCenter is fine. Reasoning: scope is one source, so cluster-wide causes are unlikely. The next check is the registered vCenter credential - a rotated service account is the classic cause. If credentials are valid, check network reachability and the proxy, then the run's task log. Restarting the job before reading the error wastes a cycle and may obscure the original cause.
Traps that cost marks
Confusing alerts with audit logs; assuming removing a node deletes its data; assuming an upgrade can proceed on a cluster with failed disks; treating a single-source failure as a cluster-wide fault; ignoring replication lag when the SLA covers the DR copy.