Why Isn’t the dd Command Wiping My Drive?

Without seeing your disk list or commands in detail, it's tricky to diagnose. You might want to try using shred instead, which is specifically designed for secure data deletion. You can find it at github.com/PartialVolume/shredos.x86_64.

Could network boot be a factor here? If your BIOS is set to boot from the network first, it could be bypassing the wipe completely. Just double-check your boot order in the BIOS settings.

Make sure you run `sync` after completing your dd command to ensure all data is fully written to the disk. Though some say dd writes directly to the disk, running sync is a good practice just to be safe.

The issue might be because you're only targeting sda instead of the individual partitions on it. You could also run dd on those partitions directly. Just be aware that if you do that, the partition table will also be wiped, which could complicate things.

It's possible your computer has hidden partitions that aren't being wiped by dd. Some systems can boot from recovery partitions without showing them in normal disk listings. Also, make sure the Windows was completely shut down and not just hibernating because that could interfere with the wipe. Check your BIOS settings for hidden partitions too. For better results, try using the drive's secure erase feature instead of dd, as it can wipe reserved sectors that dd might miss.