Silly time saving question about wiping a disk for sale

[scorcho99]

I have a 4tb parity disk that I'm going to let go, way back when it was used as a ntfs disk with some sensitive information as it was used as backup drive.

 

I installed it in a test unraid machine with a 1tb drive, a 500gb drive and a few other smaller drives. Was the act of parity syncing effectively the same as having performed a secure erase? Nothing on there can be recovered right? I actually don't care array data, just the stuff that was on the disk when it was ntfs.

 

Just a sanity check question here, it seems like the entire disk should have been filled with effectively random data or zeroes.

[BRiT]

No. Secure erase requires multiple passes with different patterns. 

[trurl]

42 minutes ago, scorcho99 said:

Just a sanity check question here, it seems like the entire disk should have been filled with effectively random data or zeroes.

If you precleared the disk, or let Unraid clear it when adding it to an array that already had valid parity, then it would have been filled with zeros. If you just put it into a new array and built parity, then it would still have whatever data was on it until that data was overwritten by other data. Formatting the disk would have overwritten just a small amount of that data, just enough to represent an empty filesystem ready to receive new folders and files. The original data would not be part of that filesystem and so not accessible in the usual way, but all its bits would still be there on the disk until overwritten.

 

Even a clear disk can supposedly have traces of the original data detectable with special techniques though not with any normal capability of the disk hardware. So

45 minutes ago, BRiT said:

No. Secure erase requires multiple passes with different patterns.