{"id":3732,"date":"2025-05-29T17:45:47","date_gmt":"2025-05-29T17:45:47","guid":{"rendered":"https:\/\/w3buddy.com\/?post_type=cposts&p=3732"},"modified":"2025-05-29T17:45:48","modified_gmt":"2025-05-29T17:45:48","slug":"mmon-mmnl-manageability-monitor-processes","status":"publish","type":"cposts","link":"https:\/\/w3buddy.com\/blog\/notes\/getting-started-with-oracle-dba\/mmon-mmnl-manageability-monitor-processes\/","title":{"rendered":"MMON & MMNL (Manageability Monitor Processes)"},"content":{"rendered":"\n

Manageability Monitor Process (MMON) and Manageability Monitor Lite Process (MMNL)<\/strong><\/h2>\n\n\n\n

The Eyes That Watch Performance \ud83d\udc40<\/p>\n\n\n\n

\ud83e\udde0 What Are MMON & MMNL?<\/h3>\n\n\n\n

MMON and MMNL are background processes that monitor and manage database performance<\/strong> through the Automatic Workload Repository (AWR)<\/strong> and Active Session History (ASH)<\/strong>. Together, they enable Oracle to detect problems, issue alerts, and support self-tuning.<\/p>\n\n\n\n

\ud83d\udd27 Responsibilities of MMON & MMNL<\/h3>\n\n\n\n
Process<\/strong><\/th>Role<\/strong><\/th>What It Does<\/strong><\/th><\/tr><\/thead>
\ud83e\udde0 MMON<\/strong><\/td>AWR Manager<\/em><\/td>Collects SGA stats<\/strong>, creates snapshots<\/strong> every 60 min, runs ADDM analysis<\/strong>, and raises performance alerts<\/strong>.<\/td><\/tr>
\ud83c\udf10 MMNL<\/strong><\/td>ASH Manager<\/em><\/td>Samples active sessions<\/strong> every second, stores in ASH buffer<\/strong>, and periodically flushes to DBA_HIST_ACTIVE_SESS_HISTORY<\/strong>.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

\ud83d\uddc2\ufe0f Where the Data Lives<\/h3>\n\n\n\n
    \n
  • \ud83d\udce6 AWR<\/strong>: Located in the SYSAUX<\/strong> tablespace, stores long-term performance history.<\/li>\n\n\n\n
  • \ud83d\udd01 ASH Buffer<\/strong>: In-memory ring buffer, holds recent session activity.<\/li>\n\n\n\n
  • \ud83d\udd04 Flush Behavior<\/strong>: MMNL flushes 1 in 10 entries<\/strong> when ASH fills or on MMON snapshot.<\/li>\n<\/ul>\n\n\n\n

    \ud83d\udca1 Why They Matter<\/h3>\n\n\n\n
      \n
    • \ud83e\udde9 Help diagnose slow queries and resource bottlenecks.<\/li>\n\n\n\n
    • \u26a0\ufe0f Automatically raise alerts on metric thresholds.<\/li>\n\n\n\n
    • \ud83d\udd04 Enable ADDM<\/strong>, AWR Reports<\/strong>, and tuning tools<\/strong>.<\/li>\n\n\n\n
    • \ud83d\udcc9 Help in trend analysis<\/strong> and capacity planning<\/strong>.<\/li>\n<\/ul>\n\n\n\n

      \ud83d\udee0\ufe0f Technical Notes<\/h3>\n\n\n\n
        \n
      • Both run as threads or OS processes<\/strong>.<\/li>\n\n\n\n
      • They also operate on Oracle ASM instances<\/strong>.<\/li>\n\n\n\n
      • AWR snapshots can be created per PDB<\/strong> or at CDB root<\/strong> level.<\/li>\n<\/ul>\n\n\n\n

        \ud83d\udcd8 Tip of the Day:<\/em>
        Want to fine-tune snapshot frequency? Adjust the AWR_SNAPSHOT_TIME<\/code> to align with your workload’s behavior \u2014 more frequent during peak hours, less during idle times.<\/p>\n","protected":false},"excerpt":{"rendered":"

        Manageability Monitor Process (MMON) and Manageability Monitor Lite Process (MMNL) The Eyes That Watch Performance \ud83d\udc40 \ud83e\udde0 What Are MMON & MMNL? MMON and MMNL are background processes that monitor and manage database performance through the Automatic Workload Repository (AWR) and Active Session History (ASH). Together, they enable Oracle to detect problems, issue alerts, and […]<\/p>\n","protected":false},"template":"","meta":{"googlesitekit_rrm_CAowu461DA:productID":""},"categories":[960,952],"class_list":["post-3732","cposts","type-cposts","status-publish","hentry","category-getting-started-with-oracle-dba","category-notes"],"_links":{"self":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/cposts\/3732","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/cposts"}],"about":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/types\/cposts"}],"wp:attachment":[{"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/media?parent=3732"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/w3buddy.com\/blog\/wp-json\/wp\/v2\/categories?post=3732"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}