Deleting data is the critical step you're likely doing wrong


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Whether at home or in the data center, chances are your deleted data is easily available to others

A key facet of the enterprise data explosion is the enormous disparity between the effort we expend on generating data compared to managing it. That isn't terribly surprising. In most business contexts, the generation of data goes hand in hand with the generation of revenue. The one element those endless piles of invoices, part drawings, production records, marketing proofs, and product photos have in common is that they were all created to chase after revenue.

However, the revenue benefits of managing data are not as easy to prove -- and almost always require more effort than companies want to expend. But there are benefits. For example, if you took all those invoices and put them into an accounting package, you could improve the efficiency of your bookkeepers and cut costs. Or if you built a content management system to house your product photos, you'd marginally decrease your storage requirements and stave off a primary storage upgrade for a few more months. Although managing data after it has been created is less sexy than making it in the first place, it can be worthwhile when done correctly.

Don't overlook deleted data

The one part of data management that has absolutely no fun associated with it is handling the very last part of data's lifecycle: its deletion. People seem to avoid deleting data like the plague -- the thought of accidentally deleting something that might be needed inspires terror. Then when data does need to be deleted, it's frequently not deleted correctly or thoroughly. The danger of allowing supposedly deleted data into the wild is ever present and requires real discipline to prevent.

How to securely delete data

How might you avoid that potentially disastrous result? You have a few options.

The least complicated way is to erase the files you want deleted and completely fill the rest of the disk with random, unimportant data. That physically overrwites that leftover "deleted" data. For example, you might delete your files and copy a bunch of MP3s onto the flash drive until it was full, then delete them as well. Anyone sleuthing around on the disk will find only those MP3s, not the important data you previously stored on it.

But doing it manually is a pain and error-prone -- especially if you're talking about a large-capacity hard disk rather than a small-capacity flash drive. To ease that effort, there are tools such as Eraser (recommended by the Electronic Frontier Foundation) and the Gnu coreutils utility Shred that either write random data across unallocated portions of a disk (ensuring that data you've already deleted is obscured) or overwrite an existing file with random data and then delete it (effectively doing the same thing, but for a single file).

However, it's important to realize that even diligent use of a fairly thorough tool like Eraser or Shred may leave behind traces. This typically occurs in file systems that implement data journaling, caching, and snapshots. You usually won't find these items on your average Windows PC, but it's very common for network administrators to implement these features to aid in disaster recovery.

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