Will Multiple Single Passes Be As Effective?

nim6us

New Member
This is actually a two parter, first question, when you set it to "Default" under how many passes it should make. What is "Default"?

AND

My main question, I was gonna run a 7 pass on all my free space, you know to really scrub clean any unknown threats. However I let it run for like four hours yesterday and it looked like it was maybe at 5% completion. I don't know if I just need to commit to leave my computer running a couple days just to get this over with. OR If perhaps I can do a 1 pass on 7 different days and get the same result?
 

DavidHB

Active Member
The answer is yes, sort of. But I don't recommend the approach.

For a free space erase on a modern drive, single pass erasing is, to all intents and purposes, as good as multiple pass erasing. The famous Gutmann 35 pass method, which has become something of a mantra, was devised as a theoretical description of what was need to deal with all the types of drive available in 1996; Gutmann explained that no single drive ever needed all these passes. Things have moved on since then, and more recent work has shown that even a single pass makes data effectively non-recoverable. When erasing specific files (where an attacker might be able to target the file location more precisely), there may be an argument for using more than one pass (I use 3), but even 7 passes is probably overkill.

Free space erasing does work the drive quite hard, and can overstress a drive that is beginning to fail. So it is probably wise not to run the free space erase more often than you have to (say once a week at most, though that's a guess rather than an informed estimate). That's why I'd just use the single pass free space erase, which can still take many hours with a large drive on a slow machine.

The real danger with all erasing is what it misses. Windows squirrels away various kinds of safety or cache copies of user data in space not marked as free, and so inaccessible to Eraser. Data can readily be recovered from these locations.One's security routine should include measures to deal with OS and application logs and clutter, shadow copies and the page file among other things. Security is not an easy business!

David
 

nim6us

New Member
Thanks for all the helpful information! I then have a follow up question, if you 3 pass on your unused space, and then emptied your recycle bin with the 3 pass system from then on, wouldn't there really be no need, security wise, to run another any pass on your unused space? Because from then on you would have effectively erased all pertinent information?
 

DavidHB

Active Member
nim6us said:
... if you 3 pass on your unused space, and then emptied your recycle bin with the 3 pass system from then on, wouldn't there really be no need, security wise, to run another any pass on your unused space? Because from then on you would have effectively erased all pertinent information?
If only life were so simple! What about all the stuff that programs running on your machine have quietly generated or downloaded and then equally quietly deleted? Explicitly erasing data you know is sensitive is certainly better than relying on free space erasing, but does not completely eliminate the need for it.

David
 

nim6us

New Member
Ahhh I see! Then there's a good reason you have the "Wizard" monkier, you've earned it sir ;)
 
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