Best Way to check ACTUAL space on SD/microSD card

Question

In the past I have read some posts by users that they have purchased a SD card from a generic vendor in another country. Although the SD/microSD card may state that it holds 128GB/512GB, the actual storage space in practice is actually much smaller, sometimes only 1-8GB!

I just was offered a huge discount on a 128GB microSD card and before I use it in my devices I would like to check that it will not corrupt my files and I will not lose any data.

Theoretically, I think I could load it with a file 127GB or so in file size and see if that entire file gets corrupted. Maybe the best choice of file would be a video file chopped and sized to 127GB....

But then again, I don't want to spend ... 20-30 HRS minimum copying this file to the SD card, and then the time to check / delete... and even where to find a video file 127GB in size. Offhand that sounds like a 24hr+ movie!

I know there must be an easy way to ascertain the actual storage size of a SD/microSD card regardless of what the file index size states it is.

Can someone suggest the best way to go about testing this?

Thanks in advance!

Solution

Disc management (Windows) or disks (Debian and derivatives) will show you the usable space. There are also command-line utilities diskpart (Windows interactive program: use list disk) and sudo fdisk -l (Linux) to show the same information.

If you format it with full sector checking, this will confirm that the whole space is accessible.

Comments

[AFH]

Disc management (Windows) or disks (Debian and derivatives) will show you the usable space. If you format it with full sector checking, this will confirm that the whole space is accessible.

[hawkhorrow]

Sounds like a great solution to me! Thanks - wanna put it in the answer field so I can acknowledge?

[Mazura]

If there's only 1~8 gigs on a 128GB card, you've been had. I'd throw it away on principle; who knows what could be embedded in it (not that it probably has 100 gigs of malware on it; just that there's already something fishy going on here).