Starting over:  clearing partitions

Last modified: Thu Jan 24 14:39:06 EST 2019

Ways to prevent partitioning, formatting, and OS-installing software from being distracted by leftover junk on reused storage devices.

CommandSimple Fast Effective Complete Universal
blkdiscard Y Y Y Y N
dd 10 MB Y Y Y N Y
wipefs Y Y ½ N Y
dd whole drive Y N Y Y Y
ATA Secure Erase N ½ Y Y N

In the details below, /dev/sdx is a placeholder for whichever device you want to clear.

blkdiscard

blkdiscard /dev/sdx instructs an SSD to "trim" all of its sectors.  In my experience, it takes between 0 and 30 seconds, and the effect is as if the drive had been zeroed out.  This is, hands down, the best option if the device supports it.

dd 10 MB

Zeroing out the first 10 megabytes, which normally takes out the partition table and the beginning of the first partition, seems to get the job done and is a great compromise when blkdiscard doesn't apply.

dd if=/dev/zero of=/dev/sdx bs=1M count=10

wipefs

wipefs will erase file system signatures from individual partitions and the partition table signature from the partition table.  It changes the minimum number of bytes to make these things "invisible for libblkid."  This generally suffices if the software to follow is going to be Linux, but otherwise not so much.  For example, I had a problem with W10 refusing to recognize a USB drive because it did not like the way it was partitioned, and wipefs didn't help.  After dd 10 MB, W10 recognized it as an empty drive.

wipefs -a /dev/sdx1
wipefs -a /dev/sdx2
...
wipefs -a /dev/sdx

dd whole drive

Super-slow, but guaranteed to work.

dd if=/dev/zero of=/dev/sdx

ATA Secure Erase

In theory, ATA Secure Erase achieves the same thing as dd whole drive in a better and faster way.  In practice, it's complicated to use, unreliable, and overkill if all you need is a clean install.


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