{"id":159,"date":"2009-03-14T15:04:54","date_gmt":"2009-03-14T04:04:54","guid":{"rendered":"http:\/\/scriptorum.imagicity.com\/?p=159"},"modified":"2009-03-14T15:04:54","modified_gmt":"2009-03-14T04:04:54","slug":"bit-rot","status":"publish","type":"post","link":"https:\/\/village-explainer.kabisan.com\/index.php\/2009\/03\/14\/bit-rot\/","title":{"rendered":"Bit Rot"},"content":{"rendered":"

[This week’s Communications column for the Vanuatu Independent.]<\/strong><\/p>\n

It\u2019s happened again.<\/p>\n

The life of a technology professional can sometimes feel like that of a doctor. You\u2019re introduced to someone, and the moment you tell them your metier, their eyes take on a particular look and they say, \u201cYou know, I\u2019ve been having this problem recently….<\/em>\u201d Immediately, the conversation becomes a diagnostic session.<\/p>\n

I suppose everyone a lawyer meets has a court case pending, too.<\/p>\n

So there I am, sitting down at a local cafe with a book and my morning coffee, and someone collars me with a request. \u201cYou need to write about CD Rot<\/em>,\u201d She says with a wry, knowing smile. Immediately, I put the book away. This is going to take some time.<\/p>\n

(Before I go on, let me say that I actually enjoy these little conversations. If I didn\u2019t, I would never have lasted as long as I have in IT. Heaven knows I wouldn\u2019t be writing this column.)<\/p>\n

<\/p>\n

CDs do rot, it\u2019s true. Well, not \u2018rot\u2019 in the sense of wood decomposing. But they do decay. Everything does. Floppy disks used to be like mayflies in this climate, often not surviving the day. USB sticks are a little better, but after a given number of write operations (admittedly large, these days) they do have a tendency to go Poof. DVDs are no better.<\/p>\n

Internal hard disks are a little more durable, by virtue of the fact that they tend hide inside the computer case, largely undisturbed. Still, it\u2019s not unusual for Father Time to catch up with them as well, in the form of the \u2018Tick of Death\u2019 \u2013 a rhythmic, metronomic tapping noise made by a faulty drive continually failing to read, resetting itself and failing again, ad infinitum.<\/p>\n

To a technician, the Tick of Death is as depressing as a death rattle. It means we have to turn to the anxious client and ask that dreaded question: \u201cDo you have backups of your files?<\/em>\u201d<\/p>\n

We know you don\u2019t, but against all hope we ask.<\/p>\n

Beyond the inevitable alphabet soup of acronyms, computer geeks have a lexicon of silly metaphors, folk tales and scraps of half-clever word play they use to encapsulate otherwise hard-to-comprehend aspects of the digital world. One of my personal favourites is the term \u2018Bit Rot\u2019.<\/p>\n

Now, bits aren\u2019t organic. They don\u2019t rot, per se. In a well-protected environment, they can remain exactly as they were for decades, theoretically forever.<\/p>\n

But storage media \u2013 the things we keep the bits in \u2013 are not so kindly served by time. They do degrade. And when they do, we are given a vivid reminder of just how ephemeral the bits and bytes of information that reside there really are.<\/p>\n

People want to treat data like a thing. They assume that if you buy some storage, and you put your bits in it, it\u2019s more or less like a safe deposit box \u2013 as long as the thing looks okay from the outside, there\u2019s no problem. Just pop the key in when you want to, and \u2013 hey presto \u2013 the data springs out, pristine and ready.<\/p>\n

Would that it were so.<\/p>\n

Data is dangerously fragile and ephemeral. It\u2019s a not-entirely-accidental collection of electrical charges that manage to emerge in some useful order… most of the time. But shift just a few of those bits around, or drop a couple on the floor, and the whole construct become no more intelligible than line noise on a telephone wire.<\/p>\n

Larger institutions with a significant investment in the information they\u2019ve stored often spend inordinate amounts of money ensuring that their bits remain ordered and accounted for. Often enough, this takes the form of large tape libraries or \u2013 more common today \u2013 vast, redundant collections of hard disks.<\/p>\n

The silly ones invest heavily on a monolithic construct built out of top-quality equipment. While it may be safely said that you really do get what you pay for when it comes to computer equipment, paying top dollar for a single basket in which to store your bits is a mug\u2019s game. Three straw baskets is vastly better than one silk purse.<\/p>\n

Google is a little smarter in their approach. No one knows the exact amount, but recent informed estimates put the number of servers they operate at well over 100,000. Each of those machines consists of a fairly decent quality board with two processors, a modest amount of RAM and a hard disk. There\u2019s no case, little duplication of core components, and it\u2019s slapped bare onto a run of the mill computer rack.<\/p>\n

When one of their servers dies, they send a technician to pull the plug, and leave it right where it is, until the rack itself is useless.<\/p>\n

You see, the folks at Google are smart. They don\u2019t really care about the computers. They care about the data. And they make sure that they always have another copy lying around. That\u2019s not a completely trivial task; it\u2019s why they have some of the best computer engineers in the world working for them.<\/p>\n

But the premise they work from is remarkably simple: Make sure you have at least 3 copies of every important file at any given time. The first copy is the one you\u2019re working on. The second copy is nearby, so you can swap it with the one you\u2019ve got without losing any time. The third one is sitting some place safe, preferably very far away.<\/p>\n

This is the fundamental principle that underlies just about everything in the formal field of Data Integrity. Sure, it\u2019s a field that you can spend a career in and still not know enough. But until you learn this first, basic lesson, you\u2019ll never learn anything: Data that doesn\u2019t exist in at least two places… doesn\u2019t really exist.<\/p>\n

Make copies early and make them often. Before you change a file, make a copy. Once you\u2019re done changing it, make a copy. When you store it, make a copy.<\/p>\n

Store those copies well. Keep one of them at hand, say on your computer or laptop hard disk. Keep another nearby, on a USB stick or a CD. Then \u2013 and this is important \u2013 keep another one offline some place. Send it to your GMail account as an attachment (these guys know how to protect data, remember?), or work out a deal with a colleague or a friend to store files on their machine.<\/p>\n

Keeping and managing multiple copies of your data is a simple process in principle. In practice, it\u2019s a pain in the posterior. But unless you want to have a long, commiserating chat with me over coffee, I\u2019d recommend you find a way.<\/p>\n

But if you\u2019ve only one copy of your files, I guarantee you it\u2019ll end in tears. I promise to be sympathetic, and I\u2019ll help you if I can, but if you haven\u2019t taken those first steps to protect yourself from Bit Rot, there\u2019s not a lot I can do. Except maybe pay for your coffee.<\/p>\n

\n

Addendum:<\/strong> In the course of dashing off this piee, I mistakenly over-write last week’s Communications column. Happily, I do occasionally take my own advice. A saved copy attached to a message in my GMail account allowed to reclaim the ‘lost’ article.<\/p>\n

So-o… I told you so.<\/p>\n

Now go back up your data.<\/p>\n","protected":false},"excerpt":{"rendered":"

People want to treat data like a thing. They assume that if you buy some storage, and you put your bits in it, it\u2019s more or less like a safe deposit box \u2013 as long as the thing looks okay from the outside, there\u2019s no problem. Just pop the key in when you want to, and \u2013 hey presto \u2013 the data springs out, pristine and ready.<\/p>\n

Would that it were so.<\/p>\n

Data is dangerously fragile and ephemeral. It\u2019s a not-entirely-accidental collection of electrical charges that manage to emerge in some useful order… most of the time. But shift just a few of those bits around, or drop a couple on the floor, and the whole construct become no more intelligible than line noise on a telephone wire.<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,5,10],"tags":[47,56,85,144,145],"class_list":["post-159","post","type-post","status-publish","format-standard","hentry","category-geek","category-journamalism","category-soft-core","tag-backup","tag-bit-rot","tag-cd-rot","tag-data-integrity","tag-data-loss"],"_links":{"self":[{"href":"https:\/\/village-explainer.kabisan.com\/index.php\/wp-json\/wp\/v2\/posts\/159","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/village-explainer.kabisan.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/village-explainer.kabisan.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/village-explainer.kabisan.com\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/village-explainer.kabisan.com\/index.php\/wp-json\/wp\/v2\/comments?post=159"}],"version-history":[{"count":0,"href":"https:\/\/village-explainer.kabisan.com\/index.php\/wp-json\/wp\/v2\/posts\/159\/revisions"}],"wp:attachment":[{"href":"https:\/\/village-explainer.kabisan.com\/index.php\/wp-json\/wp\/v2\/media?parent=159"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/village-explainer.kabisan.com\/index.php\/wp-json\/wp\/v2\/categories?post=159"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/village-explainer.kabisan.com\/index.php\/wp-json\/wp\/v2\/tags?post=159"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}