[{"data":1,"prerenderedAt":191},["ShallowReactive",2],{"term-h\u002Fhigh-availability":3,"related-h\u002Fhigh-availability":172},{"id":4,"title":5,"acronym":6,"body":7,"category":152,"description":153,"difficulty":154,"extension":155,"letter":156,"meta":157,"navigation":158,"path":159,"related":160,"seo":166,"sitemap":167,"stem":170,"subcategory":6,"__hash__":171},"terms\u002Fterms\u002Fh\u002Fhigh-availability.md","High Availability",null,{"type":8,"value":9,"toc":146},"minimark",[10,15,19,23,26,30,135,139,142],[11,12,14],"h2",{"id":13},"eli5-the-vibe-check","ELI5 - The Vibe Check",[16,17,18],"p",{},"High availability means your system keeps running even when a piece of it inevitably fails, because in production, something is always failing somewhere. It's less about preventing failure, which is impossible, and more about making sure a single dead server, a downed data center, or a flaky disk never turns into an outage your users actually notice.",[11,20,22],{"id":21},"real-talk","Real Talk",[16,24,25],{},"High availability (HA) refers to system design that minimizes downtime by eliminating single points of failure, typically through redundancy across availability zones, automated failover, health checks, and load balancing. It is usually quantified in nines of uptime, such as 99.9% (about 8.7 hours of downtime a year) or 99.99% (about 52 minutes a year), and each additional nine costs disproportionately more engineering effort than the last.",[11,27,29],{"id":28},"show-me-the-code","Show Me The Code",[31,32,37],"pre",{"className":33,"code":34,"language":35,"meta":36,"style":36},"language-yaml shiki shiki-themes material-theme-lighter material-theme material-theme-palenight","# minimal HA setup: 3 instances across 3 zones, auto-failover\nreplicas: 3\nzones: [us-east-1a, us-east-1b, us-east-1c]\nhealthCheck:\n  path: \u002Fhealthz\n  failureThreshold: 3\n  autoFailover: true\n","yaml","",[38,39,40,49,64,93,102,113,123],"code",{"__ignoreMap":36},[41,42,45],"span",{"class":43,"line":44},"line",1,[41,46,48],{"class":47},"sHwdD","# minimal HA setup: 3 instances across 3 zones, auto-failover\n",[41,50,52,56,60],{"class":43,"line":51},2,[41,53,55],{"class":54},"swJcz","replicas",[41,57,59],{"class":58},"sMK4o",":",[41,61,63],{"class":62},"sbssI"," 3\n",[41,65,67,70,72,75,79,82,85,87,90],{"class":43,"line":66},3,[41,68,69],{"class":54},"zones",[41,71,59],{"class":58},[41,73,74],{"class":58}," [",[41,76,78],{"class":77},"sfazB","us-east-1a",[41,80,81],{"class":58},",",[41,83,84],{"class":77}," us-east-1b",[41,86,81],{"class":58},[41,88,89],{"class":77}," us-east-1c",[41,91,92],{"class":58},"]\n",[41,94,96,99],{"class":43,"line":95},4,[41,97,98],{"class":54},"healthCheck",[41,100,101],{"class":58},":\n",[41,103,105,108,110],{"class":43,"line":104},5,[41,106,107],{"class":54},"  path",[41,109,59],{"class":58},[41,111,112],{"class":77}," \u002Fhealthz\n",[41,114,116,119,121],{"class":43,"line":115},6,[41,117,118],{"class":54},"  failureThreshold",[41,120,59],{"class":58},[41,122,63],{"class":62},[41,124,126,129,131],{"class":43,"line":125},7,[41,127,128],{"class":54},"  autoFailover",[41,130,59],{"class":58},[41,132,134],{"class":133},"sfNiH"," true\n",[11,136,138],{"id":137},"when-youll-hear-this","When You'll Hear This",[16,140,141],{},"\"We need high availability on the payment service, that one can't go down.\" \u002F \"Three nines sounded fine until we did the math on the downtime budget.\"",[143,144,145],"style",{},"html pre.shiki code .sHwdD, html code.shiki .sHwdD{--shiki-light:#90A4AE;--shiki-light-font-style:italic;--shiki-default:#546E7A;--shiki-default-font-style:italic;--shiki-dark:#676E95;--shiki-dark-font-style:italic}html pre.shiki code .swJcz, html code.shiki .swJcz{--shiki-light:#E53935;--shiki-default:#F07178;--shiki-dark:#F07178}html pre.shiki code .sMK4o, html code.shiki .sMK4o{--shiki-light:#39ADB5;--shiki-default:#89DDFF;--shiki-dark:#89DDFF}html pre.shiki code .sbssI, html code.shiki .sbssI{--shiki-light:#F76D47;--shiki-default:#F78C6C;--shiki-dark:#F78C6C}html pre.shiki code .sfazB, html code.shiki .sfazB{--shiki-light:#91B859;--shiki-default:#C3E88D;--shiki-dark:#C3E88D}html pre.shiki code .sfNiH, html code.shiki .sfNiH{--shiki-light:#FF5370;--shiki-default:#FF9CAC;--shiki-dark:#FF9CAC}html .light .shiki span {color: var(--shiki-light);background: var(--shiki-light-bg);font-style: var(--shiki-light-font-style);font-weight: var(--shiki-light-font-weight);text-decoration: var(--shiki-light-text-decoration);}html.light .shiki span {color: var(--shiki-light);background: var(--shiki-light-bg);font-style: var(--shiki-light-font-style);font-weight: var(--shiki-light-font-weight);text-decoration: var(--shiki-light-text-decoration);}html .default .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}html.dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}",{"title":36,"searchDepth":51,"depth":51,"links":147},[148,149,150,151],{"id":13,"depth":51,"text":14},{"id":21,"depth":51,"text":22},{"id":28,"depth":51,"text":29},{"id":137,"depth":51,"text":138},"architecture","High availability means your system keeps running even when a piece of it inevitably fails, because in production, something is always failing somewhere.","intermediate","md","h",{},true,"\u002Fterms\u002Fh\u002Fhigh-availability",[161,162,163,164,165],"Fault Tolerance","Resilience","Availability Zone","Auto-Failover","Load Balancer",{"title":5,"description":153},{"changefreq":168,"priority":169},"weekly",0.7,"terms\u002Fh\u002Fhigh-availability","UNWfojfvJGyTqEdGT8tihBGVhLbYoGnUlQrw3FhlALM",[173,177,181,184,188],{"title":164,"path":174,"acronym":6,"category":175,"difficulty":154,"description":176},"\u002Fterms\u002Fa\u002Fauto-failover","cloud","Auto-failover automatically switches to a backup system when the primary one fails — no human intervention needed. Your database server dies at 3 AM?",{"title":163,"path":178,"acronym":179,"category":175,"difficulty":154,"description":180},"\u002Fterms\u002Fa\u002Favailability-zone","AZ","An Availability Zone is one of several separate data centers within a cloud region.",{"title":161,"path":182,"acronym":6,"category":152,"difficulty":154,"description":183},"\u002Fterms\u002Ff\u002Ffault-tolerance","Fault tolerance is designing a system that assumes parts of it will break, so it plans for that instead of hoping it doesn't happen.",{"title":165,"path":185,"acronym":6,"category":186,"difficulty":154,"description":187},"\u002Fterms\u002Fl\u002Fload-balancer","networking","A load balancer is like a traffic cop for servers.",{"title":162,"path":189,"acronym":6,"category":152,"difficulty":154,"description":190},"\u002Fterms\u002Fr\u002Fresilience","Resilience is your system's ability to get punched in the face by a dependency going down, a traffic spike, or a bad deploy, and keep serving users anyway...",1792528091065]