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I found CCleaner very useful to clean all unnecessary data on a hard drive and wipe out free space.

But what makes it different from normal delete to secure delete, and I wonder what it will do on hard drive for secure delete and to wipe out on free space?

If I use secure delete option very often to delete data or wipe free space option, will it damage hard drive in the long run or will it reduce the life time of hard disk?

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if you really want to secure your data you should not rely on secure delete but on something like harddrive encryption. if it were possible to reliably read data that is overwritten once, why doesn't this double our harddrives capacity? –  Baarn Dec 30 '11 at 14:08
    
@sri If you want secure deletion you should use a program like eraser.heidi.ie –  Simon Sep 15 '13 at 20:35
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3 Answers

Short answer:

  • Traditional HDD (mechanical): no
  • SSD: yes

Long answer: A traditional mechanical hard drive will lose a small amount of life span, but it's so negligible that it really doesn't matter at all. Doing this on a SSD, however, makes absolutely no sense. Not only will it decrease the lifespan of the disk (although TRIM is supposed to help a little with that), but modern computer forensics are not even applicable to SSDs since they operate in totally different ways (read this article for more info).

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That raises the issue of "bad blocks" also for hard drives. things that get put aside that are never cleared. There was a security artical recentally , discussing all the things they can find on old wiped hard drives. –  Psycogeek Dec 30 '11 at 14:36
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In all honesty, unless you are an extremely paranoid person that worries if their computer were physically stolen, someone might recover stuff you deleted, i don't think you need to worry about secure delete. What it does is simply zero out the part of the drive where the data was residing, effectively scrubbing the remains of the file.

In most cases, when a file is deleted from a drive, the drive simply MARKS the area of the drive clear, but if you used data recovery tools before the computer used that space to write a different file, you could get the file back. Secure delete simply overwrites those file remains.

It could be argued that yes this will shorten the life of the drive, while others would say you are crazy. I feel if the drive's life would be shortened by it, the time would be negligible at best, but it's up to you, it shouldn't hurt it anymore than a trip to the corner gas station would hurt your car.

Whether you feel those trips to the gas station are necessary or not, is up to you.

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Needless wiping/overwriting of the data, would be more problematic for flash drives. The heads of the hard drive do not touch the surfaces (until bumped when running) The magnetic materials can change back and forth endlessly. Hard drives generally, die in an early stage of life (defect) or they live as long as the moving mechanical parts of them would survive for.

If the computer/drive is not treated carefully , and you have needless writing, the head is over the data area more often, it would increase the (slight) possibility of it getting damaged when abused. If there is no UPS for the computer, it would increase the chances of a minor corruption on power loss, doing unnessisary writing.

On the other hand, depending on the OS , something like windows can be writing all the time needlessly, so who cares, it would not change anything :-)

Once the clusters are marked for deletion, they will be overwritten soon enough , when new data comes in and writes into those spaces.

Overwriting 7 times is overdoing the whole idea, doing a single overwrite on a stable system, should not change any life expectancy of the drive. One overwrite is enough to hide the data even from higher end recovery or forensics.

A user might want to have a Balance of security , You would not be able to recover something you accidentally deleted/cleaned yourself. How many times does a person make misteaks vrses how many times other people are trying to mess with them.

In a journaling os (leftovers), and with so many things being all over the registry, and with many index.dat files that dont clear easily, layers of caching, if you really need to hide everything, its going to take more than Ccleaner :-) With a few hours on a system that is fully "cleaned and secured", I can find layers of breadcrumbs they left all over, without me even trying to seek them out. New programs and ideas and updates adding in new yet cleaned items , the process of full hiding best be done with a degausser :-)

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