Micro SD cards are up to about ~290 MB/s for read times these days, IIRC. That's...

onlyrealcuzzo · on July 15, 2021

That's throughput.

IOPS is important.

For random 4kb blocks / second

SD Card => 2.1 [1]

SSD => ~200 [2]

[1] https://www.cameramemoryspeed.com/reviews/micro-sd-cards/

[2] https://en.wikipedia.org/wiki/IOPS

And that's comparing good SD cards to good SSDs.

As I was saying, bad SD cards can be REALLY bad. The difference can be over 1000x. Anything that depends on being able to read ANY small piece of information regularly in a reasonable amount of time from disk would simply not be playable.

minsc__and__boo · on July 15, 2021

That's assuming the games are writing to the SD cards and not the SSD though, right?

If this is Debian/Arch OS, I'd assume they are writing to a system folder.

onlyrealcuzzo · on July 15, 2021

No - those are random READS - not writes.

If the game is on the SD Card - it will be read from the SD card.

Sure, if the game needs to randomly write data to disk (I assume this is much rarer) - then it would write to the system SSD as usual.

minsc__and__boo · on July 16, 2021

Got it. So SD cards are optimized for large, continuous file reads, not varied file reads.

onlyrealcuzzo · on July 19, 2021

I'm not sure that's what they're optimized for. I think it's more of just that's how the technology works.

It's the same way I wouldn't say that film is optimized for storing lots of data with horrible access cheaply. It just happens to be what it is.