How to securely wipe your ReadyNAS

This thread is slightly dated but I wanted to reply and say that the instructions above seem to have worked for me on my old ReadyNAS NV.

I followed the instructions and installed the Secure Delete package, then ran the "srm -rv /c/" command via SSH. It was a piece of cake. I could see where it deleted a couple empty directories as well as the admin and home folders. Then it got to a folder where I still had some non-sensitive files. It got to the first file and displayed a "Wiping (file name) **" message... and it has been sitting at that for about 40 minutes now. So I don't see any indication of exactly what it is doing now but the activity LED on my NAS is steadily flashing so I assume it is wiping the drives successfully. I don't know if it is still on that first file or if it is just not updating the console any more. And of course I will have no way to check how good a job it is doing with the actual obliteration process.

I did spend quite a bit of time backing up my files and the deleting them from the NAS for what it's worth. So just to be clear, can I assume that those deleted files will be wiped as well or do I need to run another command to wipe the free space?

Also, my ReadyNAS NV partitions were created with the old 4K block size. My plan was to do a factory reset after this which will rebuild the array/partitions with a 16K block size. Will this have any impact one way or the other on making it easier or harder for someone to recover any data from my drives? I was thinking of trying to sell them on eBay either separately or as a group.

Thanks.