Difficulty: ★★★☆☆
There are USB sticks and SD cards in circulation that are not of the specified size. Often you only notice this when you have lost data. But there is a way to test it. This is not laborious, but time-consuming!
-
Choose one of your USB sticks with USB2 or 3 (A 64GB USB stick is used in the examples below)
-
Install the
f3
package from the AUR:pamac install f3
test the USB stick for the real size:
Insert the USB stick and see what kind of device ID it got. The easiest tool to use is: lsblk
:
lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 931,5G 0 disk
├─sda1 8:1 0 953M 0 part /boot/efi
├─sda2 8:2 0 900G 0 part /var/spool
└─sda3 8:3 0 28,1G 0 part
sdb 8:16 0 476,9G 0 disk
├─sdb1 8:17 0 512M 0 part
└─sdb2 8:18 0 476,4G 0 part
sdz 8:32 1 59,5G 0 disk
nvme0n1 259:0 0 1,9T 0 disk
├─nvme0n1p1 259:1 0 1G 0 part
├─nvme0n1p2 259:2 0 1M 0 part
├─nvme0n1p3 259:3 0 900G 0 part
└─nvme0n1p4 259:4 0 1006,7G 0 part
PLEASE check again that
/dev/sdz
is really your USB stick and not part of your Manjaro system.
- Safely remove the device
- Unplug
- Plug it back in
-
Test with
lsblk
again!
The USB stick must have disappeared from the list!
- Safely remove the device
- Unplug
- Plug it back in
-
Test with
lsblk
again!
The device should have reappeared. If you are not sure then stop here: If you enter the wrong device with the next command, you will wreck your whole system with one command !
Those who checked well can now test the USB stick. The USB stick will be deleted !!! (So save data that you still need beforehand)
sudo f3probe --destructive --time-ops /dev/sdz
F3 probe 8.0
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.
WARNING: Probing normally takes from a few seconds to 15 minutes, but
it can take longer. Please be patient.
Good news: The device `/dev/sdz' is the real thing
Device geometry:
*Usable* size: 59.53 GB (124846080 blocks)
Announced size: 59.53 GB (124846080 blocks)
Module: 64.00 GB (2^36 Bytes)
Approximate cache size: 0.00 Byte (0 blocks), need-reset=no
Physical block size: 512.00 Byte (2^9 Bytes)
Probe time: 3'53"
Operation: total time / count = avg time
Read: 5.39s / 4816 = 1.1ms
Write: 3'46" / 4192321 = 54us
Reset: 0us / 1 = 0us
I hope your stick is as good as mine
Good news: The device ‘/dev/sdz’ is the real thing
And the Usable size: 59.53 GB (124846080 blocks) is as advertised
Test the stick for data security and speed
- Use gparted to format the stick as a single partition with exfat (about 59GiB) and name “test”. The USB stick will be deleted !!! (So save data that you still need beforehand)
- unplug,
- plug in,
- Mount the USB sick (the stick now is empty)
For me, the stick ends up in/run/media/andreas/test/
. You have to adapt this to your mount point.
Now we fill the stick completely with data.
Warning:
This takes a really long time. For me it was about 2 hours with USB2 and 64 GB
Writing the stick this way will shorten the life of your USB stick through wear leveling, so don’t do it to often.
f3write /run/media/andreas/test
F3 write 8.0
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.
Free space: 59.53 GB
Creating file 1.h2w ... OK!
Creating file 2.h2w ... OK!
...
Creating file 59.h2w ... OK!
Creating file 60.h2w ... OK!
Free space: 0.00 Byte
Average writing speed: 7.75 MB/s
Now we just have to read the data again and compare. Warning: it takes a really long time. With USB2 and 64 GB it was also almost 2 hours.
f3read /run/media/andreas/test
F3 read 8.0
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.
SECTORS ok/corrupted/changed/overwritten
Validating file 1.h2w ... 2097152/ 0/ 0/ 0
Validating file 2.h2w ... 2097152/ 0/ 0/ 0
Validating file 3.h2w ... 2097152/ 0/ 0/ 0
Validating file 4.h2w ... 2097152/ 0/ 0/ 0
...
Validating file 58.h2w ... 2097152/ 0/ 0/ 0
Validating file 59.h2w ... 2097152/ 0/ 0/ 0
Validating file 60.h2w ... 1103104/ 0/ 0/ 0
Data OK: 59.53 GB (124835072 sectors)
Data LOST: 0.00 Byte (0 sectors)
Corrupted: 0.00 Byte (0 sectors)
Slightly changed: 0.00 Byte (0 sectors)
Overwritten: 0.00 Byte (0 sectors)
Average reading speed: 12.48 MB/s
I hope your stick is as good as mine
Data LOST: 0.00 bytes (0 sectors)
Note: The full instructions for f3 can be found here
- my USB-stick was good
- my USB-stick had errors
- my USB-stick is a fake (much smaller then advertised)
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