2018 15'' MBP with 512GB SSD actual writing speed

[santolie]

Hi friends,

I just received my new 2018 15'' MBP with some configurations (i9, 512GB SSD, 32GB Ram). I'm happy about most aspects of the machine, but sort of confused by the test results I get from running BlackMagic Disk Speed Test. I ran my test on both BlackMagic and AJA (as shown below) and constantly have a mere 1700MB/s write and 2600MB/s read.

So I've seen many videos and articles claim how fast the new MacBook Pro's SSD runs, and they are mostly featuring the bigger drives, from 1TB to 4TB. Their results are mostly around 2500MB/s write and 2600MB/s read, which is higher than what Apple advertised. And I've read some articles that said bigger SSD tends to perform better speed than the smaller ones. But would the difference of write speed between a 512GB and 1TB more than 40%?

Am I having a problem with the write speed? I still haven't seen other people posted about their SSD write speed if they have a 512GB model.

 

[Lennyvalentin]

Am I having a problem with the write speed? I still haven't seen other people posted about their SSD write speed if they have a 512GB model.

In a word, no, you're not having a problem... These speed tests are by and large not illustrative of real-world conditions. They're kinda like taking your car to a drag strip to check its performance, and thus not getting any information how it corners, turning radius, how easy it is to park, how it handles rough roads or terrain... (Car analogies are always the best, isn't that so? lol)

And yes, larger capacity SSDs typically perform better than smaller capacity SSDs of the same model series. Why that is; simply put, larger drive = more flash dies which can be accessed in parallel, thus boosting performance. However that requires either writing very large chunks of data all at once (which rarely happens in the real world except in a few types of apps, like video editing for example), or having very high levels of I/O operations queued up (which again rarely happens in single-user scenarios.)

Thus, simplistic benchmark apps that shows a speedometer type dial for your SSD speed is not really going to give you a good, accurate representation of the true speed of your SSD. If you're really interested in the deep-down nitty-gritty, check Anandtech for a 2018 Macbook Pro review; they tend to do good disk performance benchmarks, based on recordings of the disk access patterns of real, actual professional software.

 

[johnalan]

Not a problem, I have the 512gb SSD on the 2018 i7 2.6ghz - I see the EXACT same speeds as you.

I made a thread on it and others with the 512 confirmed the speed as the same on their machine.

It's not an issue, just the 1tb and 4tb has a faster write.

 

[maflynn]

Am I having a problem with the write speed?

I have a 512GB SSD in my 2018 MBP and the speeds you listed are consistent with my MBP. I'm not worried about the performance, it is still wicked fast and I don't think its an issue.

 

[santolie]

They're kinda like taking your car to a drag strip to check its performance, and thus not getting any information how it corners, turning radius, how easy it is to park, how it handles rough roads or terrain... (Car analogies are always the best, isn't that so? lol)

Thank you for the awesome car analogies and thorough explanation. I work in photography and sometimes do video editing, it's good to know how and why the SSD performed differently. Now I'm more relieved.
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Not a problem, I have the 512gb SSD on the 2018 i7 2.6ghz - I see the EXACT same speeds as you.

I have a 512GB SSD in my 2018 MBP and the speeds you listed are consistent with my MBP

Thank you for sharing both of your speed! Really helpful.