The Maximum Sessions alert notifies you when its configured condition is met on Oracle instances so you can investigate and respond.
Mini DBA describes this alert as: Maximum concurrent sessions to the Oracle instance This may indicate periods of very high use or inefficient application connection pooling Mini DBA evaluates this alert once a minute so changes are detected quickly.
This alert warns that client connections or database sessions are approaching a configured capacity limit. Reaching the limit can reject new work even when CPU and storage still have headroom.
Enable it where exhausting the connection or session limit would interrupt application traffic. Establish a normal concurrency baseline first, then leave enough warning margin to diagnose connection leaks, login storms, or undersized limits.
Threshold meaning: Sessions. Major threshold: 400 sessions. Minor threshold: 300 sessions. Comparison direction: over. For an over-threshold alert, decreasing a threshold makes that severity fire sooner; increasing it tolerates more load or pressure. Set the minor threshold as an early-warning level and the major threshold at the highest acceptable value for the service.
Identify which applications and logins own the open sessions, then check connection-pool reuse, idle-session lifetime, retry storms, and recent traffic changes. Correct leaks or churn before increasing the engine limit, and raise the limit only when host capacity and platform guidance support it.
If the alert creates repeated noise, review whether it is enabled on the correct instances, whether maintenance windows are configured, and whether the minor and major routes match the real business impact. Keep enough history to prove the new setting before changing it broadly.