disk-test

Block device read-write test utility written in bash

Type: Command line application
Platforms: Linux, possibly other Unix-style operating systems
Written in: Bash

Manual pages

disk-test.1

Usage

disk-test
  [-a|--actions actions]
  [-b|--block-size blockSize]
  [-c|--count-bytes numberOfBytes]
  [-s|--skip-bytes numberOfBytes]
  [--]
  deviceOrFile

disk-test [--help]

Tests if a device can write and correctly read arbitrary data over its entire reported size, or over a specified range.

Actions

In particular, performs an arbitrary sequence of actions on the device or on a range thereof. The desired sequence is given as a string of characters. Available actions are:

w – Write pseudo-random data
z – Write zeros
v – Read and verify the data written by the most recent preceding write action
r – Read, but do not verify, the data on the device

Terminates with exit code 2 if the data being read is not identical to the data that has been written before (in case of "v"), or if a device-related error occurs.

The pseudo-random data varies for each "w" action and is generated by encrypting a stream of zeros with 256-bit AES in CTR mode, which should be reasonably fast and usually outperforms /dev/urandom.

Use cases

The primary use case is to assess data storage mediums' correct operation with the goal of preventing data loss. To give some examples, the utility may be used to

detect manufacturing flaws in newly purchased data storage mediums
test mediums that are being repurposed or have been acquired second-hand
identify fraudulent data storage mediums that report greater capacities than they actually provide

Apart from preventing data loss, identifying faulty devices well ahead of a warranty's or defects liability's deadline may avoid unnecessary expenses.

Used data storage mediums should be wiped before they are sold; using disk-test on them is one way to achieve this within reasonable time while on the same occasion indicating damaged mediums that should not be put up for sale.

The utility may also be used to estimate devices' bulk read and particularly write speeds of incompressible data, notably of mediums that traditionally struggle with data writing throughput such as USB thumb drives, SD cards and low-capacity solid state disks.

Examples

Testing, then zeroing a new 500 GB Kingston A2000 M.2 NVMe PCIe SSD (SA2000M8/500G):

[user@system ~]$ su -c 'disk-test --actions wvwvz -- /dev/nvme0n1' root
Password: 
 INFO  Testing block device or file: "/dev/nvme0n1"
 INFO  Performing 5 action(s): "wvwvz"
 INFO  Action 1/5 (w) on device "/dev/nvme0n1": Wvwvz
 INFO  Writing pseudo-random:  465GiB 0:27:50 [ 285MiB/s] [==================>] 100%
 INFO  Action 2/5 (v) on device "/dev/nvme0n1": wVwvz
 INFO  Reading and comparing:  465GiB 0:14:00 [ 567MiB/s] [==================>] 100%
 INFO  Action 3/5 (w) on device "/dev/nvme0n1": wvWvz
 INFO  Writing pseudo-random:  465GiB 0:26:12 [ 303MiB/s] [==================>] 100%
 INFO  Action 4/5 (v) on device "/dev/nvme0n1": wvwVz
 INFO  Reading and comparing:  465GiB 0:13:47 [ 576MiB/s] [==================>] 100%
 INFO  Action 5/5 (z) on device "/dev/nvme0n1": wvwvZ
 INFO  Writing zeros:  465GiB 0:24:54 [ 319MiB/s] [==========================>] 100%
 INFO  Finished, no errors: "/dev/nvme0n1"
[user@system ~]$

Testing, then zeroing a new 18 TB Toshiba MG09 series Enterprise Capacity SATA HDD (MG09ACA18TE), which took about 5 days:

[root@system ~]# disk-test --block-size 32M --actions wvzv -- /dev/sdc
 INFO  Testing block device or file: "/dev/sdc"
 INFO  Performing 4 action(s): "wvzv"
 INFO  Using custom block size "32M"
 INFO  Action 1/4 (w) on device "/dev/sdc": Wvzv
 INFO  Writing pseudo-random: 16.4TiB 38:54:19 [ 122MiB/s] [=================>] 100%
 INFO  Action 2/4 (v) on device "/dev/sdc": wVzv
 INFO  Reading and comparing: 16.4TiB 22:39:22 [ 210MiB/s] [=================>] 100%
 INFO  Action 3/4 (z) on device "/dev/sdc": wvZv
 INFO  Writing zeros: 16.4TiB 35:13:42 [ 135MiB/s] [=========================>] 100%
 INFO  Action 4/4 (v) on device "/dev/sdc": wvzV
 INFO  Reading and comparing: 16.4TiB 22:39:20 [ 210MiB/s] [=================>] 100%
 INFO  Finished, no errors: "/dev/sdc"
 [root@system ~]#

A fake 32 GB microSD card was found to only have 7.5 GiB of actual storage space:

[user@system ~]$ sudo disk-test --actions wvz /dev/sdb
Password:
 INFO  Testing block device or file: "/dev/sdb"
 INFO  Performing 3 action(s): "wvz"
 INFO  Action 1/3 (w) on device "/dev/sdb": Wvz
 INFO  Writing pseudo-random: 31.2GiB 0:26:35 [20.1MiB/s] [==================>] 100%
 INFO  Action 2/3 (v) on device "/dev/sdb": wVz
 INFO  Reading and comparing: 7.50GiB 0:06:51 [18.7MiB/s] [====>               ] 23%
error writing output file
ERROR  Reading and comparing pseudo-random data failed with return value 1
[user@system ~]$

Usage recommendations for SMART-capable devices

When testing devices that support SMART error reporting, as do virtually all SATA devices and many USB-connected HDDs and SSDs, it is a good idea to retrieve and store a SMART error report before testing. After testing it can be compared against a new SMART report to see whether certain telltale attribute values have deteriorated.

If the RAW_VALUE of these attributes has increased the device's reliability might be compromised (this list is incomplete):

Reallocated_Sector_Ct
Reallocated_Event_Count

SMART reports can be retrieved with the "smartctl -a <device>" command; smartctl is part of smartmontools.

SMART-capable devices usually support running self-tests, typically a superficial one ("short") and a complete scan ("long"). HDDs often also offer a "conveyance" test.

It is a good idea to run the complete/long SMART self-test on the device in addition to disk-test. A device can be told to run this self-test with the command "smartctl -t long <device>"
This self-test is faster than disk-test but still takes some time; as a ballpark figure for HDDs assume about 1 hour per TB.

After completion the test results will be shown in the SMART report in the respective section.

Also, before and after the complete/long self-test look out for these SMART attributes; they are typically only updated during such a self-test. If their RAW_VALUE has increased the device might have reliability problems (list also incomplete):

Offline_Uncorrectable
Multi_Zone_Error_Rate

License

GNU General Public License version 3

Packages

Arch Linux
Ubuntu: See Releases for .deb files
Debian: See Releases for .deb files

Browseable sources

These source files of the latest tag can be viewed in the browser:

disk-test

Releases

Trunk

15 February 2020 (2020-02-15 00:10:44 UTC)

Indent usage section in the help text

disk-test-0.2.4

15 February 2020 (2020-02-15 00:01:03 UTC)

disk-test-0.2.4.tar.gz SHA256 checksum SHA384 checksum PGP signature

disk-test_0.2.4-1-ubuntu-20.04-focal_all.deb SHA256 checksum SHA384 checksum PGP signature

disk-test_0.2.4-1-ubuntu-22.04-jammy_all.deb SHA256 checksum SHA384 checksum PGP signature

disk-test_0.2.4-1-debian-11-bullseye_all.deb SHA256 checksum SHA384 checksum PGP signature

Add an actions summary to the help text
Tweak documentation of the --actions argument
Hide a shellcheck warning where the code is intentional

disk-test-0.2.3

03 November 2019 (2019-11-03 16:19:28 UTC)

disk-test-0.2.3.tar.gz SHA256 checksum SHA384 checksum PGP signature

Fix some code style issues pointed out by shellcheck

disk-test-0.2.2

26 September 2019 (2019-09-26 20:16:50 UTC)

disk-test-0.2.2.tar.gz SHA256 checksum SHA384 checksum PGP signature

Manual page: Add documentation for exit code 0
Manual page: Fix the listing of available actions; the last bullet point should have had "r" as character

disk-test-0.2.1

25 September 2019 (2019-09-25 18:19:40 UTC)

disk-test-0.2.1.tar.gz SHA256 checksum SHA384 checksum PGP signature

Fix behavior of the trailing arguments marker "--"
Ensure that the required program "realpath" is available
Replace detailed output of --help with a proper manual page, disk-test(1)
Fix a typo in a comment
Improve error messages when failing to determine the device's or file's size

disk-test-0.2.0

24 September 2019 (2019-09-24 16:53:18 UTC)

disk-test-0.2.0.tar.gz SHA256 checksum SHA384 checksum PGP signature

Implement proper ERROR messages for missing programs
Report all missing programs in bulk instead of just the first one
Check for required programs "blockdev" and "stat" up front
Make sure required program "sed" is available
Add a TODO for a manual page
Implement option "-b|--block-size" to specify a custom read/write block size
Implement option "-c|--count-bytes" to specify the width of a custom range to test, in bytes
Implement option "-s|--skip-bytes" to specify an offset from which to test, in bytes
Implement option "-a|--actions" to specify a custom sequence of actions to be performed on the device
Add support for the device being given as a symbolic link; the symbolic link will be resolved in this case
Implement proper arguments parsing: disk-test --arg-1 x --arg-2 y device
Changed description in README

disk-test-0.1.1

01 October 2018 (2018-10-01 21:10:44 UTC)

disk-test-0.1.1.tar.gz SHA256 checksum SHA384 checksum PGP signature

Relicensing from GPLv3-or-later to GPLv3
Prepared disk-test 0.1.1
Removed warning about deprecated key derivation function from openssl enc by specifying PBKDF2 with a single iteration
Added iflag=fullblock to the dd call for random password generation

disk-test-0.1.0

30 April 2018 (2018-04-30 22:10:28 UTC)

disk-test-0.1.0.tar.gz SHA256 checksum SHA384 checksum PGP signature