#90 hdparm --sanitize-overwrite do not have an option to change the count parameter and default value

[Michal Grzedzicki]

Count param for OVERWRITE EXT command specifies how many times the pattern will be overwritten. It's a 3 bit value but 0 is special meaning 16 overwrites.

For bigger drives this means the drive will be sanitising for 2 weeks instead of a day. This command is persistent so there's no way to stop it. If you are not expecting this it may seem like you just bricked a drive like described in https://tinyapps.org/docs/ata_sanitize_hdparm.html paragraph 7

Doing more than 1 overwrite doesn't make much sense on todays drives and 16 is for sure an overkill.

https://people.freebsd.org/~imp/asiabsdcon2015/works/d2161r5-ATAATAPI_Command_Set_-_3.pdf pdf page 228
"
7.36.4.3.3 OVERWRITE PASS COUNT field
The OVERWRITE PASS COUNT field specifies the number of overwrite passes (i.e., how many times the data in the
user area is to be overwritten) using the data from the OVERWRITE PATTERN field of this command. An overwrite
pass count of zero specifies 16 overwrite passes.
"

Attached example patch changing the default to 1.

Thanks,
Michal

[Mark Lord]

Not a bug. It does what one asks it to do.
If one wants just a single-pass erase, then use "--security-erase" instead.

But I'm totally open to anyone who wants to submit a patch which adds a command-line option to specify the exact number of sanitize cycles.

Cheers

[Michal Grzedzicki]

Hi Mark,
did you have a time to look at the path bellow ?

[Michal Grzedzicki]

adding patch adding option to specify the pass count

[Mark Lord]

I have renamed the new flag to be "--sanitize-overwrite-passes" to avoid confusion with existing flags where "-pass" refers to a password. Otherwise, applied for hdparm-9.63.