Re: Wiping a disk partition

On 6/26/25 00:38, Odhiambo Washington wrote:
> On Thu, Jun 26, 2025 at 3:05 AM David Christensen wrote:
>> On 6/25/25 03:16, Odhiambo Washington wrote:
>>> root@gw:/home/wash # df -h
>>> Filesystem     Size    Used   Avail Capacity  Mounted on
>>> /dev/ada0p2    1.8T    552G    1.1T    33%    /
>>> devfs          1.0K      0B    1.0K     0%    /dev
>>> fdescfs        1.0K      0B    1.0K     0%    /dev/fd
>>> procfs         8.0K      0B    8.0K     0%    /proc
>>> linprocfs      8.0K      0B    8.0K     0%    /compat/linux/proc
>>> linsysfs       8.0K      0B    8.0K     0%    /compat/linux/sys
>>> /dev/ada1p2    1.8T    856G    802G    52%    /disk2
>>> ```
>>>
>>> What is the fastest way to wipe all data on /dev/ada1p2?
>>
>> # camcontrol security ada1 -U user -s MyPass -e MyPass
> 
> So I looked at mine:
> 
> ```
> root@gw:/ # camcontrol security ada1
> pass1: <Samsung SSD 870 EVO 2TB SVT02B6Q> ACS-4 ATA SATA 3.x device
> pass1: 600.000MB/s transfers (SATA 3.x, UDMA6, PIO 512bytes)
> 
> Security Option           Value
> supported                 yes
> enabled                   no
> drive locked              no
> security config frozen    yes
> count expired             no
> security level            high
> enhanced erase supported  yes
> erase time                4 min
> enhanced erase time       8 min
> master password rev       fffe
> ```
> 
> However, I actually do not need "secure erase". I only wanted to know the
> fastest way of emptying the partition.


Another approach could be rm(1) followed by a manual TRIM of the 
filesystem.  This should remove the files and directories, and erase the 
blocks behind them, on the /disk2 filesystem.


Beware of using the confusingly named trim(8) command (!):

https://freebsd-hackers.freebsd.narkive.com/o3g3PuaA/how-to-use-trim-command


fsck_ufs(8) appears to be the right tool for a manual TRIM.  So (untested):

# rm -rf /disk2/* /disk2/.?*

# fsck_ufs -E /disk2


I ran `fsck_ufs -E /` on my SOHO file server, but could not tell if any 
TRIM commands were executed (?).  Adding the debug option `-d` did not help.


A third approach could be to enable TRIM on the filesystem in fstab(5), 
reboot, and then run rm(1).  I would expect rm(1) and disk write 
performance to be reduced:

# vi /etc/fstab

/dev/ada1p2	/disk2		ufs	rw	1	2

# shutdown -r now

# rm -rf /disk2/* /disk2/.?*


David