{"id":1337,"date":"2007-11-04T12:00:00","date_gmt":"2007-11-04T12:00:00","guid":{"rendered":"http:\/\/orcldoug.com\/blog\/?p=1337"},"modified":"2007-11-04T12:00:00","modified_gmt":"2007-11-04T12:00:00","slug":"the-reality-gap-2-disaster-recovery","status":"publish","type":"post","link":"http:\/\/orcldoug.com\/blog\/2007\/11\/04\/the-reality-gap-2-disaster-recovery\/","title":{"rendered":"The Reality Gap (2) &#8211; Disaster Recovery"},"content":{"rendered":"<p>I&#8217;m going to keep this one short and sweet because I&#8217;ve <a href=\"http:\/\/18.133.199.212\/?p=1120\">talked about it before<\/a>. <\/p>\n<p>Because it&#8217;s based around a single shared database, RAC will <strong>not<\/strong> (and was never designed to) protect you from <\/p>\n<ul>\n<li>Database corruption<\/li>\n<li>Erroneous updates or deletes by a user (or DBA!)<\/li>\n<\/ul>\n<p>More to the point, all of the following tools will happily replicate any human error to your second copy :-<\/p>\n<ul>\n<li><a href=\"http:\/\/en.wikipedia.org\/wiki\/SRDF\">SRDF<\/a> (and other storage-level replication tools)<\/li>\n<li>Data Guard<\/li>\n<li>Other replication solutions (e.g. Shareplex and the like)<\/li>\n<\/ul>\n<p>Unless you have a <strong>delay<\/strong> built in to the replication that gives you time to notice the screw-up and do something about it.<\/p>\n<p>When protecting yourself against disasters, why do we spend so much time and money on protecting ourselves against major site disasters, but much less time and brain-power on protecting ourselves against what I would suggest are far more common &#8211; simple human screw-ups?<\/p>\n<p>Think about it :-<\/p>\n<ul>\n<li>How many times have you screwed up or been sitting next to someone who did?<\/li>\n<li>How many times have you lost a machine room because of an earthquake, fire or explosion?<\/li>\n<li>How many times have you had to restore a database to cure a problem?<\/li>\n<li>How many times have you had to cut-over to your DR site for real? (Not in a practice run)<\/li>\n<\/ul>\n<p>I&#8217;m not saying people shouldn&#8217;t have DR plans in place, but I&#8217;m tired of hearing SRDF sold to managers as the solution to all problems! Reality Gap!<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I&#8217;m going to keep this one short and sweet because I&#8217;ve talked about it before. Because it&#8217;s based around a single shared database, RAC will not (and was never designed to) protect you from Database corruption Erroneous updates or deletes by a user (or DBA!) More to the point, all of the following tools will&hellip; <a class=\"more-link\" href=\"http:\/\/orcldoug.com\/blog\/2007\/11\/04\/the-reality-gap-2-disaster-recovery\/\">Continue reading <span class=\"screen-reader-text\">The Reality Gap (2) &#8211; Disaster Recovery<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1337","post","type-post","status-publish","format-standard","hentry","category-uncategorized","entry"],"jetpack_featured_media_url":"","jetpack-related-posts":[{"id":1120,"url":"http:\/\/orcldoug.com\/blog\/2006\/11\/02\/recovery-design-part-4-you-need-more-than-one-database\/","url_meta":{"origin":1337,"position":0},"title":"Recovery Design part 4 &#8211; You need more than one database","date":"November 2, 2006","format":false,"excerpt":"There was a good reaction to part 3 with sensible comments from people who've obviously 'been there, seen it, done it, bought the t-shirt' and handled their share of tricky system failures, so thanks to all. The comments are interesting reading for other perspectives and ideas.Although the sub-title to this\u2026","rel":"","context":"With 4 comments","img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1267,"url":"http:\/\/orcldoug.com\/blog\/2007\/05\/18\/log-buffer-45\/","url_meta":{"origin":1337,"position":1},"title":"Log Buffer #45","date":"May 18, 2007","format":false,"excerpt":"It's my turn again and, looking back at Log Buffer #4, I was amazed to realise that we're up to number 45 already and that my previous attempt was last August. Good work from Dave Edwards, who bears the organisational burden every week. Sooner him than me!I'll kick off this\u2026","rel":"","context":"With 2 comments","img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1339,"url":"http:\/\/orcldoug.com\/blog\/2007\/11\/06\/the-reality-gap-3-a-single-instance-per-server\/","url_meta":{"origin":1337,"position":2},"title":"The Reality Gap (3) &#8211; A Single Instance per Server","date":"November 6, 2007","format":false,"excerpt":"There will probably be about four or five of these posts in total. This is one I didn't mention in the original presentation because I didn't feel I could do it justice and because there was someone I wanted to have the right to reply. Step forward Tom Kyte.By coincidence,\u2026","rel":"","context":"With 15 comments","img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1207,"url":"http:\/\/orcldoug.com\/blog\/2007\/02\/17\/dst\/","url_meta":{"origin":1337,"position":3},"title":"DST","date":"February 17, 2007","format":false,"excerpt":"Three letters that I am positively sick of hearing. I remember reading about this first on Peter K's blog and - shame on me - it registered but wasn't top of my to do list. Well, it is now. Several other bloggers including Chris Foot have talked about the changes\u2026","rel":"","context":"With 5 comments","img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1002,"url":"http:\/\/orcldoug.com\/blog\/2006\/06\/20\/mysterious\/","url_meta":{"origin":1337,"position":4},"title":"Mysterious &#8230;","date":"June 20, 2006","format":false,"excerpt":"... and quite funny. I followed an incoming link through Statcounter and arrived here.At the moment, the content is :-SQL> startup mountORACLE instance started.Total System Global Area 645922816 bytes Fixed Size 1250644 bytes Variable Size 184552108 bytes Database Buffers 457179136 bytes Redo Buffers 2940928 bytes Database mounted.SQL> alter database open;Database\u2026","rel":"","context":"With 3 comments","img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1044,"url":"http:\/\/orcldoug.com\/blog\/2006\/08\/04\/tracing-session-activity-over-a-remote-database-link\/","url_meta":{"origin":1337,"position":5},"title":"Tracing session activity over a remote database link","date":"August 4, 2006","format":false,"excerpt":"Yesterday someone asked me how to trace a session that selects from a view in a remote database via a link. If they activated the trace on the local instance, they wouldn't see the bulk of the work which was happening on the remote instance - just a bunch of\u2026","rel":"","context":"With 2 comments","img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]}],"_links":{"self":[{"href":"http:\/\/orcldoug.com\/blog\/wp-json\/wp\/v2\/posts\/1337","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/orcldoug.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/orcldoug.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/orcldoug.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/orcldoug.com\/blog\/wp-json\/wp\/v2\/comments?post=1337"}],"version-history":[{"count":0,"href":"http:\/\/orcldoug.com\/blog\/wp-json\/wp\/v2\/posts\/1337\/revisions"}],"wp:attachment":[{"href":"http:\/\/orcldoug.com\/blog\/wp-json\/wp\/v2\/media?parent=1337"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/orcldoug.com\/blog\/wp-json\/wp\/v2\/categories?post=1337"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/orcldoug.com\/blog\/wp-json\/wp\/v2\/tags?post=1337"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}