[轉貼]No such thing as "deleted" on the Internet

 你以為在把貼在網路上的圖片「刪除」，圖片就真的不見了嗎？Think again!

底下是一篇轉自美國Yahoo!網站的文章，相信看過之後你會對於網路上所謂的「刪除」功能有更多的認識。

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No such thing as "deleted" on the Internet

(http://tech.yahoo.com/blogs/null/142366)

 Thu May 21, 2009 11:51AM EDT


It's always fun to write about research that you can actually try out for yourself.

Try this: Take a photo and upload it to Facebook, then after a day or so,
note what the URL to the picture is (the actual photo, not the page on
which the photo resides), and then delete it. Come back a month later
and see if the link works. Chances are: It will.

Facebook isn't alone here. Researchers at Cambridge University (so you know this is legit, people!) have found that nearly half of the social networking sites don't immediately delete pictures
when a user requests they be removed. In general, photo-centric
websites like Flickr were found to be better at quickly removing
deleted photos upon request.

Why do "deleted" photos stick around
so long? The problem relates to the way data is stored on large
websites: While your personal computer only keeps one copy of a file,
large-scale services like Facebook rely on what are called content
delivery networks to manage data and distribution. It's a complex
system wherein data is copied to multiple intermediate devices, usually
to speed up access to files when millions of people are trying to
access the service simultaneously. (Yahoo! Tech is served by dozens of
servers, for example.) But because changes aren't reflected across the
CDN immediately, ghost copies of files tend to linger for days or weeks.

In the case of Facebook, the company says data may hang around until the
URL in question is reused, which is usually "after a short period of
time." Though obviously that time can vary considerably.

Of course, once a photo escapes from the walled garden of a social network
like Facebook, the chances of deleting it permanently fall even
further. Google's caching system is remarkably efficient at archiving
copies of web content, long after it's removed from the web. Anyone
who's ever used Google Image Search can likely tell you a story about
clicking on a thumbnail image, only to find that the image has been
deleted from the website in question -- yet the thumbnail remains on
Google for months. And then there are services like the Wayback Machine, which copy entire websites for posterity, archiving data and pictures forever.

The lesson: Those drunken party photos you don't want people to see? Simply
don't upload them to the web, ever, because trying to delete them after
you sober up is a tough proposition.

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 對於懶得看英文直接把捲軸拉到底的人......我就先把結論說了吧。

就是：

「不想要讓別人看到的東西，打從一開始就不要絕對不要上傳！」

End of the story.