Erasing a drive that I have already replaced and do I need to?


May 13, 2017
I have a pool made up to 6 x 2-way mirrors. The pool was setup that way from the beginning. Shortly after setting up the pool and copying some data it, I found one of the drives was starting to fail, so I took it offline and replaced it with a good drive.

But, since the drive is still working, I'm concerned that my data can be read/recovered after I returned my drive for RMA.

With my pool configuration, is it possible for someone to peice together data from 1 of the 6 vdevs I had in the pool? It would seem that the data is only 1 of 6 parts, if I understand how things works correctly.

If I do need to wipe the drive, I don't have any open bays on my TrueNAS server. Any recommendations on how I could wipe it, perhaps by connecting it with a USB enclosure or alike?

Thank you.
Oct 22, 2019
If you pop it into a USB enclosure, you can plug it into any spare PC, boot into a live Linux distro (via USB boot), and then issue the "dd" command to write zeros across all sectors. Just make sure you don't accidentally wipe the wrong drive!

An example of such:
dd if=/dev/zero bs=1M status=progress of=/dev/sdc

BONUS POINTS: After it's wiped, format the drive in Windows with NTFS, and copy a bunch of Linux ISOs into a folder called "Downloads".


Hall of Famer
Aug 16, 2011
is it possible for someone to peice together data from 1 of the 6 vdevs I had in the pool?
A sufficiently-motivated adversary might be able to pull some individual files from that disk, if they were small enough. I'd think it pretty unlikely they'd try, but in theory it could be possible. You could have avoided this concern by encrypting the pool or by using self-encrypting disks.

Failing that, if you want to be on the safe side, what Winnie suggested is a good rough-and-ready approach. You could also use something like DBAN to securely wipe any data on the disk.