f3probe

Probe a block device

$ sudo f3probe [path/to/block_device]

$ sudo f3probe --min-memory [path/to/block_device]

$ sudo f3probe --time-ops [path/to/block_device]

f3probe [options]

-s
    Sets probe size to size. The default is the entire device.

-n
    Sets the number of blocks to analyze.

-r
    Read-only mode: only reads from disk. Use for analysis of previous written data.

-v
    Verbose mode: Display additional information.

-h
    Display help message and exit.

-t
    Write test files for f3read

f3probe is a command-line tool designed for quickly detecting fake or unreliable storage capacity in flash memory devices such as USB drives, SD cards, and SSDs. It writes test patterns across the entire device and then reads them back, comparing the data for errors. This helps identify drives that falsely report a larger capacity than they actually possess, or that are prone to data corruption.

While f3probe identifies the *potential* for data corruption, it does not guarantee complete data safety. It provides a quick assessment; more thorough testing might be needed for critical applications. It helps avoid storing critical files on corrupted or fake disks, and will try to determine real capacity.

f3probe is destructive. It will overwrite data on the specified device unless used with the -r option. Always back up important data before using f3probe.
The reliability of flash media can degrade over time, even for legitimate devices. f3probe provides a snapshot of the device's integrity at the time of testing, but does not guarantee future reliability.

f3probe exits with 0 on success, and >0 if any errors occurred.

f3probe is part of the Fight Flash Fraud (F3) suite, which aims to detect and prevent the use of counterfeit or unreliable flash memory devices. Development was likely spurred by the proliferation of fake USB drives and SD cards that falsely advertise their capacity. The tool has become increasingly useful as the market for flash memory has grown and the potential for fraud has increased.
The suite (f3probe, f3read and f3write) are open source and have been widely adopted in the communities to verify the claimed memory sizes.

f3read(1), f3write(1)