Drive wiper data options

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1

Would it be possible to add options to drive wiper to state what data should be used when wiping?

I gather from another thread here that the data currently used is all zeros.

From reading around other forums, this is supposed to be better for virtual disks. Random is supposed to be better from a confidential data overwrite perspective. Writing ones is apparently what the TRIM function does with SSDs.

My interest is from the SSD side; I'm using SSDs that sit on a RAID controller and consequently TRIM doesn't work. It would be nice to have the option of TRIMming SSDs manually.

Thanks. :)

2

The specific answer to your suggestion is that TRIM doesn't write ones (or zeroes, or anything) to an SSD page. It flags that page as being available for garbage collection, which is a process that 'empties' the page of data, i.e. sends all those electrons back to the right side of the gate. An empty SSD cell is interpreted as a one. However you will not see a page full of ones as the empty pages are held back and used as new pages when data is written. Thus every page you will ever see will always contain at least one zero. If you read an empty page the SSD controller will generate a default page of zeroes and return that. (The process with MLC SSD's is rather more complicated, but the principle is the same.)

So the data pattern when wiping an SSD is irrelevant. Wiping an SSD is also irrelevant, as you can't overwrite an SSD page (it does have some use on non-TRIM enabled devices, which are a little long in the tooth now).

Somebody else can comment on TRIMming a raid array, as I'm not au fait with that technology.

3

Hi Augeas, thanks for the input.

I don't necessarily mean running a RAID array, although I am doing that as well; I do have single disks that don't TRIM because they're attached to the RAID card. The controllers these days have garbage collection built-in, even without TRIM, but some of my drives have slowed somewhat, and as far as others are reporting, the way to fix it was to wipe with high values. It is not my area of expertise. :unsure: