[zfs-discuss] zfs eradication

[David Magda]

On Nov 10, 2009, at 20:55, Mark A. Carlson wrote:

>Typically this is called "Sanitization" and could be done as part of
>an evacuation of data from the disk in preparation for removal.
>
>You would want to specify the patterns to write and the number of
>passes.

See also "remanence":

	http://en.wikipedia.org/wiki/Data_remanence

(S)ATA actually has a protocol command ("secure erase") that will  
cause the disk to over write all of its sectors, and not be usable  
until its done. This doesn't exist in SCSI / SAS / FC as far as I know.

Generally speaking one over write is sufficient to prevent data from  
being accessible, but various government standards specify anywhere  
between one and four passes:

	http://en.wikipedia.org/wiki/Data_erasure

Degaussing or complete destruction is usually necessary for the "top  
secret" stuff. DBAN is a useful (open-source) utility that I tend to  
recommend for regular folk:

	http://www.dban.org/

While it could be useful, there are penalties in various jurisdictions  
for leaking data (especially with government-related stuff), so I'm  
not sure if Sun would want to potentially expose itself to  
inappropriate use that doesn't clean everything properly.

With ZFS encryption coming up, it could be sufficient to have your  
data sets encrypted and then simply "forget" the key. The data is  
still technically there, but (theoretically) completely inaccessible.

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