{"id":2315,"date":"2026-02-03T16:31:02","date_gmt":"2026-02-03T14:31:02","guid":{"rendered":"https:\/\/www.ludovicocaldara.net\/dba\/?p=2315"},"modified":"2026-02-03T16:31:02","modified_gmt":"2026-02-03T14:31:02","slug":"dg26ai-4-observers","status":"publish","type":"post","link":"https:\/\/www.ludovicocaldara.net\/dba\/dg26ai-4-observers\/","title":{"rendered":"Data Guard 26ai &#8211; #6: Up to four Fast-Start Failover Observers"},"content":{"rendered":"<p dir=\"auto\"><a href=\"https:\/\/www.ludovicocaldara.net\/dba\/dg-26ai-series\/\">This post is part of a blog series.<\/a><\/p>\n<p dir=\"auto\">Just like<a href=\"https:\/\/www.ludovicocaldara.net\/dba\/dg26ai-observer-priority\/\"> observer priorities,<\/a> this is another cool feature first introduced in Oracle 21c.<\/p>\n<p dir=\"auto\">If your Fast-Start Failover setup doesn\u2019t have a third site for the observer, the usual advice is to place it with your primary database. But if you want true high availability, making sure the observer is always up, you\u2019ll want two observers on the primary site and two on the secondary site (for when the standby takes over as primary).<\/p>\n<p dir=\"auto\">Before 21c, you could only use up to three observers, which made this setup impossible.<\/p>\n<p dir=\"auto\"><a href=\"https:\/\/www.ludovicocaldara.net\/dba\/wp-content\/uploads\/2026\/01\/dg26ai-4-observers.png\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-large wp-image-2313\" src=\"https:\/\/www.ludovicocaldara.net\/dba\/wp-content\/uploads\/2026\/01\/dg26ai-4-observers-1024x466.png\" alt=\"a diagram shows two databases in a Data Guard configuration, each with its two preferred local observers.\" width=\"584\" height=\"266\" srcset=\"https:\/\/www.ludovicocaldara.net\/dba\/wp-content\/uploads\/2026\/01\/dg26ai-4-observers-1024x466.png 1024w, https:\/\/www.ludovicocaldara.net\/dba\/wp-content\/uploads\/2026\/01\/dg26ai-4-observers-300x136.png 300w, https:\/\/www.ludovicocaldara.net\/dba\/wp-content\/uploads\/2026\/01\/dg26ai-4-observers-768x349.png 768w, https:\/\/www.ludovicocaldara.net\/dba\/wp-content\/uploads\/2026\/01\/dg26ai-4-observers-1536x699.png 1536w, https:\/\/www.ludovicocaldara.net\/dba\/wp-content\/uploads\/2026\/01\/dg26ai-4-observers-2048x932.png 2048w, https:\/\/www.ludovicocaldara.net\/dba\/wp-content\/uploads\/2026\/01\/dg26ai-4-observers-500x227.png 500w\" sizes=\"auto, (max-width: 584px) 100vw, 584px\" \/><\/a><\/p>\n<pre class=\"lang:plsql highlight:0 decode:true\">edit database db_site1 set property PreferredObserverHosts='obs1_site1,obs2_site1';\r\nedit database db_site2 set property PreferredObserverHosts='obs1_site2,obs2_site2';<\/pre>\n<p dir=\"auto\">Starting with 21c (and, of course, 26ai), you can now configure four observers. That solves the high-availability challenge when you\u2019ve only got two sites.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Now you can run four Fast-Start Failover observers\u2014even with just two sites\u2014thanks to a handy Oracle 21c feature included in 26ai. <a href=\"https:\/\/www.ludovicocaldara.net\/dba\/dg26ai-4-observers\/\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[375,329],"tags":[],"class_list":["post-2315","post","type-post","status-publish","format-standard","hentry","category-oracle-ai-database-26ai","category-oracle-dg"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.ludovicocaldara.net\/dba\/wp-json\/wp\/v2\/posts\/2315","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ludovicocaldara.net\/dba\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ludovicocaldara.net\/dba\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ludovicocaldara.net\/dba\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ludovicocaldara.net\/dba\/wp-json\/wp\/v2\/comments?post=2315"}],"version-history":[{"count":4,"href":"https:\/\/www.ludovicocaldara.net\/dba\/wp-json\/wp\/v2\/posts\/2315\/revisions"}],"predecessor-version":[{"id":2405,"href":"https:\/\/www.ludovicocaldara.net\/dba\/wp-json\/wp\/v2\/posts\/2315\/revisions\/2405"}],"wp:attachment":[{"href":"https:\/\/www.ludovicocaldara.net\/dba\/wp-json\/wp\/v2\/media?parent=2315"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ludovicocaldara.net\/dba\/wp-json\/wp\/v2\/categories?post=2315"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ludovicocaldara.net\/dba\/wp-json\/wp\/v2\/tags?post=2315"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}