I ran across this a while back:<\/p>\n
http:\/\/www.electronista.com\/articles\/08\/12\/17\/toshiba.512gb.ssd\/<\/p>\n
…in which the author breathlessly proclaims: “Longevity is also a focus with about one million hours (114 years) between failures thanks to reduced wear on potentially short-lived memory cells.”<\/p>\n
Wrong.<\/p>\n
I often get asked about MTBF (Mean Time Between Failure) and it’s amazing how many “industry people” don’t understand it.<\/p>\n
And for those who have already figured out that their 1.5M MTBF drives don’t last 171 years, but are not sure what that MTBF thing is… here’s a vastly oversimplified quickie:<\/p>\n
Why your hard drive doesn’t last 150 years.<\/p>\n
(There are about 8700 hours in a year, but to make this example simple, let’s call it 10,000.)<\/p>\n
Here’s how MTBF works: it’s an aggregate of many units based on expected life of a single unit.<\/p>\n
Let’s say you have a hard drive that is warranted to last 3 years, or 30,000 hours.<\/p>\n
You put it in a server, and behold, it lasts 3 years. You take it out and put in a new one, and that also lasts 3 years. So you replace it with a new one, and that too…. well, you get it.<\/p>\n
Let’s say you keep doing that and finally, on the 50th unit, only two years into it’s life, it breaks.<\/p>\n
You now have 3 years or 30,000 hours per unit, times 50 units = 1,500,000.<\/p>\n
And that’s your MTBF.<\/p>\n
So anyone who says “Wow! MTBF of 1.5 million hours! that mean this thing will last (1.5M \/ 10000) 150 years!” -clearly- doesn’t know what they’re talking about.<\/p>\n
(I have grossly oversimplified the description of MTBF calculation in order to make the general point that it is NOT life-expectancy. MTBF is more complex than my example, including “infant mortality” and “wear out” phases; “theoretical” vs “operational” MTBF and so on, but the gist of what’s here is correct.)<\/p>\n","protected":false},"excerpt":{"rendered":"
I ran across this a while back: http:\/\/www.electronista.com\/articles\/08\/12\/17\/toshiba.512gb.ssd\/ …in which the author breathlessly proclaims: “Longevity is also a focus with about one million hours (114 years) between failures thanks to reduced wear on potentially short-lived memory cells.” Wrong. I often get asked about MTBF (Mean Time Between Failure) and it’s amazing how many “industry people” […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-247","post","type-post","status-publish","format-standard","hentry","category-mac-tips"],"_links":{"self":[{"href":"https:\/\/valleau.art\/blog\/wp-json\/wp\/v2\/posts\/247","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/valleau.art\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/valleau.art\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/valleau.art\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/valleau.art\/blog\/wp-json\/wp\/v2\/comments?post=247"}],"version-history":[{"count":1,"href":"https:\/\/valleau.art\/blog\/wp-json\/wp\/v2\/posts\/247\/revisions"}],"predecessor-version":[{"id":248,"href":"https:\/\/valleau.art\/blog\/wp-json\/wp\/v2\/posts\/247\/revisions\/248"}],"wp:attachment":[{"href":"https:\/\/valleau.art\/blog\/wp-json\/wp\/v2\/media?parent=247"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/valleau.art\/blog\/wp-json\/wp\/v2\/categories?post=247"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/valleau.art\/blog\/wp-json\/wp\/v2\/tags?post=247"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}