Slow SSD speeds on 2019 MacBook Pro 13" 128GB

[shimon88]

Hi all,

I have a 2019 MacBook Pro 13" with 128GB SSD and 16GB ram.
currently I'm utilizing 40% of the available storage.

on Blackmagic I'm getting around 380MB/s write and 1250 MB/s read.
the read seems reasonable but the write is like SATA drives.

is that normal? should I contact Apple?
thanks,

Shimon

 

[ilikewhey]

did apple advertised higher speed for your 128gb model?

i wont be surprised if thats its as high as it can go, since 128gb sized nand package doesn't allow higher write speed compared to 256gb and higher

 

[Jochheim]

I would also argue that those write speeds are quite low. On my 2015 MBP 13" I got almost the same results but at least around 450MB/s write and I thought the speed increased with future models like yours. So I would search for other user data and then maybe contact apple. For perspective: My new 2020 MBP (4TB with 512) gets around 2300 for both.

 

[ilikewhey]

I would also argue that those write speeds are quite low. On my 2015 MBP 13" I got almost the same results but at least around 450MB/s write and I thought the speed increased with future models like yours. So I would search for other user data and then maybe contact apple. For perspective: My new 2020 MBP (4TB with 512) gets around 2300 for both.

mate you got way more storage ofcourse your speed is much faster

 

[Jochheim]

@ilikewhey : Sure, but the discrepancy with those speeds from shimon88 are pretty extreme, don't you think? Of course you will get better results with bigger SSD´s but I was not aware that the jump from 128 to 512 would be this big (if you look at some user data from the 2020 SSD speed thread, the speed differences seem to be almost non existent - but there are no 128 options of course).

 

[ilikewhey]

@ilikewhey : Sure, but the discrepancy with those speeds from shimon88 are pretty extreme, don't you think? Of course you will get better results with bigger SSD´s but I was not aware that the jump from 128 to 512 would be this big (if you look at some user data from the 2020 SSD speed thread, the speed differences seem to be almost non existent - but there are no 128 options of course).

fair enough. however you be surprised, normally on consumer ssd, the write speed jump from 128 to 256 is double, and double again from 256 to 512, after 512 the write speed becomes a controller limitation for most of the case, ofcourse i'm stating all this on what i used to do when i was building gaming pcs back in the day.

 

[mj_]

Like @ilikewhey said this is absolutely normal for SSDs. There's a linear correlation between both read and write speed and number of flash chips available. Both reads and writes are performed in parallel with writes being much more strenuous and time-consuming than reads. That's why with, say, 6 flash chips you may get 200 MB/s read per chip but only 50 MB/s write speed resulting in a combined performance of 1,200 MB/s read but only 300 MB/s write. Double the number of flash chips and capacity and you're looking at double the read and double the write speed, at least in theory. The read speed is going to hit the bus ceiling sooner rather than later and remain at 1,200 MB/s (assuming that is the actual limit of the PCIe bus) but write speed will double to 600 MB/s due to the linear increase in write parallelism. Double the number of flash chips yet again (note: we went from 6 to 12 to 24 now) and you will once again double theoretical read and write performance. With the bus capped at 1,200 MB/s you are now looking at reads and writes of 1,200 MB/s each.

That's why low-capacity SSDs are always slower than high-capacity SSDs.

 

[ilikewhey]

Like @ilikewhey said this is absolutely normal for SSDs. There's a linear correlation between both read and write speed and number of flash chips available. Both reads and writes are performed in parallel with writes being much more strenuous and time-consuming than reads. That's why with, say, 6 flash chips you may get 200 MB/s read per chip but only 50 MB/s write speed resulting in a combined performance of 1,200 MB/s read but only 300 MB/s write. Double the number of flash chips and capacity and you're looking at double the read and double the write speed, at least in theory. The read speed is going to hit the bus ceiling sooner rather than later and remain at 1,200 MB/s (assuming that is the actual limit of the PCIe bus) but write speed will double to 600 MB/s due to the linear increase in write parallelism. Double the number of flash chips yet again (note: we went from 6 to 12 to 24 now) and you will once again double theoretical read and write performance. With the bus capped at 1,200 MB/s you are now looking at reads and writes of 1,200 MB/s each.

That's why low-capacity SSDs are always slower than high-capacity SSDs.

Took the word right out of my mouth, however I was way to lazy to go into details 😂

 

[shimon88]

Thank you all. Guess It would have beeb better returning this one and replacing it with 8gb/256gb..but it’s too late

 

[mj_]

If it makes you feel any better you're not going to notice the difference anyway. Reading is much more important, and most writes are in the realm of a few KB to a few MB.

 

[ilikewhey]

If it makes you feel any better you're not going to notice the difference anyway. Reading is much more important, and most writes are in the realm of a few KB to a few MB.

yeah honestly all this speed is just on paper, or if you do alot of large video file transfers, otherwise you won't really notice it. frankly any sata ssd speed is good enough for most folks.

 

[shimon88]

Yeah I get that.
Just wanted an opinion whether should I be concerned that the SSD might be failing or something.
Seems normal so moving on