At Mon, 14 Sep 2020 13:14:44 -0700 CentOS mailing list <centos@xxxxxxxxxx> wrote:
>
> Folks
>
> I've encountered situations where I want to reuse a hard-drive. I do
> not want to preserve anything on the drive, and I'm not concerned
> about 'securely erasing' old content. I just want to be able to
> define it as an Physical Volume (in a logical volume set), or make it
> a ZFS disk, or sometimes make it a simple EXT3, ExFAT or NTFS
> disk. However, old 'signatures' get in the way and Linux sometimes
> refuses to let me proceed. I know that a fool-proof solution is to
> use the "dd if=/dev/zero bs=32768 oflag=direct" on the disk, but when
> we're talking USB-connected hard drives of 8 TB, that's an operation
> that can take days.
>
> The disk in question might even have been corrupted. This would make
> using 'zpool destroy' to clear out a ZFS disk, or
>
> I've tried erasing the first megabyte of the disk, but there are ZFS
> or LVM structures that get in the way. So, does anyone have an
> efficient way to erase structures from a disk such that it can be reused?
>
> Something like
> -erase first N blocks (block defined as 4096)
> - Erase <number> blocks starting at block <number>
> - erase last <number> blocks
Use dd in a script:
#!/bin/bash
# erase N 4K blocks starting at M
# (M=0 means from the start of the disk)
# usage: $0 start4Kblock numberof4Kblocks drive
M = $1
N = $2
rawdisk = $3
dd if=/dev/zero bs=4096 oflag=direct count=$N seek=$M of=$rawdisk
> At least such an algorithm would be quicker than erasing 8 TB of data.
>
> David
>
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