How to zero a disk + verify it afterward?

debugcn 에 게시 Dev

yael

We have a relatively large disk on our Linux machine, 2.5TB in size.

We want to completely format (zero-out) this disk; say the disk is /dev/sdX.

We would like to achieve this with dd, for example:

dd if=/dev/zero of=/dev/sdX bs=1M count=1

My question is: Does dd also support such a formatting (cleaning) of disks with large sizes?

Additionally, what could be the verification method after such dd operation, in order to see if the disk has really been zeroed?

LinuxSecurityFreak

dd would be slow in this instance.

You could install pv (man page) with:
```
yum install pv
```
pv could be faster and I would suggest scrambling instead of zeroing, first, (if you are serious about the data erasure, that is):
```
pv < /dev/urandom > /dev/sdX
```
There is no need of checking if this has been done. In this instance, where we would be scrambling instead of zeroing, there is no way anyways.
If you wish to zero the whole drive now, simply do:
```
pv < /dev/zero > /dev/sdX
```
If the drive has been zeroed, now you can check if it's really zeroed with:
```
pv /dev/sdX | tr --squeeze-repeats "\000" "Z"
```
Example output:
```
1,00MiB 0:00:00 [ 202MiB/s] [=============================>] 100%            
Z
```
Noticed the one and only letter Z as the output? That's what you're looking for in here.

Taken from https://superuser.com/a/559794/402107

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에서 수정2021-06-4

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