Interesting


Free space: 23.07 GB
Average writing speed: 42.01 MB/s

Why is there 23 GB free on that micro SD card? You won’t get the up to 90 MB/s write very often if at all, I think the highest I saw was around 70 MB/s, and it didn’t stay writing that fast. I’m using a USB 3.0 card reader, or some other version of USB 3.

That is with f3write. But if you run df -h ., it says:


df -h .
Filesystem      Size  Used Avail Use% Mounted on
/dev/sdl1       453G  430G     0 100% /mnt/sd

It’s a 512 GB micro SD card. Don’t recall if any other cards said there was any free space left after running f3write. You do get less space when formatted, but why don’t I get 453G for the size of the partition? Isn’t 512G – 453G the amount lost from formatting? Or the amount lost from their different measurements.

Too lazy to test a different micro SD card. If everything reads back fine, I’ll probably keep it.

Would be funny if the other cards said some amount of free space, and I never noticed.

I could delete the partition, and remake it. And see if the size decreases.

According to somebody’s pastebin, it said “Free space: 0.00 Byte” after f3write finished, but it’s a fake card.

Hmm, over provisioning, don’t recall if my Switch micro SD card had free space as well.

It’s formatted to ext4. The card is a PNY XLR8 512GB, yes I’m cheap. Might cost slightly more then my Switch micro SD card cost though, and that is a cheaper brand. If I’m not careful, I might kill the Switch micro SD card, they are fragile. I think I killed the old one from the same brand, can’t recall the brand. Silicon Power maybe?

f3write –start-at=xxx might do something, except df -h reports no space available.

I was going to get a 1 TB micro SD card, but the PNY was only $60, around $130 for 1 TB.

Don’t think any of the Amazon reviewers, tested it with f3write. Now to go shit.

According to one answer here, it’s reserved space.

5% of 453 is 22.65 according to DuckDuckGo. No, I don’t know math. Says if you are root, you can write to that space. So perhaps I usually run it as root.

I’m too lazy/impatient to run f3write again. Running f3read now. I could cheat, and use the –start or whatever option as root, and not rewrite the entire drive, can you do that for f3read too?


  Data OK: 429.78 GB (901304704 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: 94.01 MB/s

The read speed is as advertised. Well, you could say the write is as well, it’s “up to”. Oh wait, the read speed is supposed to be 100 MB/s, probably up to. Close enough.

Also my Kingston card reader, might not be the fastest. It’s better then the card reader I was using before I got this one.

The SD card is good as far as I’m concerned.

I don’t think I ever got a fake SD card, I don’t usually buy SanDick, the most popular brand. Less likely to get a fake card buying the cheaper brands.