Test real and fake disks for bad blocks
Time and Throughput
For a disk with 128GB capacity and an average throughput of 85MB/s, this test takes around 50 minutes. The formula for computing the test duration is t=2*V/B
(i.e., the time in seconds multiplied by the volume in megabytes divided by the average bandwidth in megabytes per second). The factor of 2 is attributable to transferring twice for writing and reading.
This results in a mean bandwidth of B=2*V/t
. The exact size of the data medium can be discovered by lsblk -b /dev/$device
. If you substitute the value into the formula, you can compute the bandwidth in bytes per second.
A buyer can assume a defect or a fake if measuring the data medium reveals a figure of less than a quarter of the "up to" figure stated by the manufacturer, or less than half of the nominal value. However, you do need to use a connection with the maximum speed for the test, for example, a UHS-II reader for a UHS-II memory card.
Happy Ending
Returning to my two 128GB test cards, bad block
reported 122,973,232 defective blocks from a total 131,071,999 blocks (of 1024 bytes each) for the first card – in other words, 94 percent of the blocks are broken. The second card, on the other hand, showed no errors. According to the formula t=2*V/B
, the test duration should be about one hour, which was true of the second card, which passed the line after about 70 minutes. The test of the first card took too long – over five hours.
The test with badblocks
thus exposed the following about the first card: it was a fake with many faults and was incredibly slow. When I confronted the vendor with these hard facts, I convinced him to take back the card and refund the amount paid. The second and intact card, however, works perfectly in combination with a short SD card adapter with a pull tab as the second SSD in my laptop.
Infos
- SD cards/counterfeits: https://en.wikipedia.org/wiki/Secure_Digital#Counterfeits
- USB storage/manipulated controller chips (German only): https://de.wikipedia.org/wiki/USB-Massenspeicher#Manipulierte_Controllerchips
- Identifying fakes: http://linuxwelt.blogspot.de/2014/06/microsd-speicherkarten-falschungen.html
- disktest1.sh: ftp://ftp.linux-magazine.com/pub/listings/linux-magazine.com/201/
« Previous 1 2
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Canonical Bumps LTS Support to 12 years
If you're worried that your Ubuntu LTS release won't be supported long enough to last, Canonical has a surprise for you in the form of 12 years of security coverage.
-
Fedora 40 Beta Released Soon
With the official release of Fedora 40 coming in April, it's almost time to download the beta and see what's new.
-
New Pentesting Distribution to Compete with Kali Linux
SnoopGod is now available for your testing needs
-
Juno Computers Launches Another Linux Laptop
If you're looking for a powerhouse laptop that runs Ubuntu, the Juno Computers Neptune 17 v6 should be on your radar.
-
ZorinOS 17.1 Released, Includes Improved Windows App Support
If you need or desire to run Windows applications on Linux, there's one distribution intent on making that easier for you and its new release further improves that feature.
-
Linux Market Share Surpasses 4% for the First Time
Look out Windows and macOS, Linux is on the rise and has even topped ChromeOS to become the fourth most widely used OS around the globe.
-
KDE’s Plasma 6 Officially Available
KDE’s Plasma 6.0 "Megarelease" has happened, and it's brimming with new features, polish, and performance.
-
Latest Version of Tails Unleashed
Tails 6.0 is based on Debian 12 and includes GNOME 43.
-
KDE Announces New Slimbook V with Plenty of Power and KDE’s Plasma 6
If you're a fan of KDE Plasma, you'll be thrilled to hear they've announced a new Slimbook with an AMD CPU and the latest version of KDE Plasma desktop.
-
Monthly Sponsorship Includes Early Access to elementary OS 8
If you want to get a glimpse of what's in the pipeline for elementary OS 8, just set up a monthly sponsorship to help fund its continued existence.