Jimmyjames
Site Champ
- Joined
- Jul 13, 2022
- Posts
- 922
I noticed something strange from a review X Elite yesterday. There was a comparison between the X Elite and the MacBook Air M3 15”. One section measures ssd performance. Usually the only thing they mention is sequential read and write speed, despite being less important in day to day use for most people. What stood out to me was the discrepancy in random write speeds.
This is the comparison:
We can see the random 4k write with a queue depth of 32 is 398 MB/s on the X Elite and 94 MB/s. With queue depth at 1 the X Elite scores 185MB/s while the M3 scores 37MB/s.
At first I thought it might be an issue of the number of nand chips used in the ssd, as there was some discussion of this a year or so ago. It seems like the Air in this example is a 1 TB model, so shouldn’t suffer the same slowdown. Then I thought it might be the result of Apple’s firmware, and their insistence on guaranteeing the ssd actually flushes writes to the nand. Something which doesn’t actually happen on many ssds. Apple writes their own firmware for the shipping ssds to make sure Force Unit Access and F_FULLSYNC is honoured. The drawback of this is it can slow down writes.
Then I tested my 2018 Intel Mac Mini:
Hmmmm, why is my six year old Intel box destroying the latest Apple Silicon machines in random writes? I am puzzled.
This is the comparison:
We can see the random 4k write with a queue depth of 32 is 398 MB/s on the X Elite and 94 MB/s. With queue depth at 1 the X Elite scores 185MB/s while the M3 scores 37MB/s.
At first I thought it might be an issue of the number of nand chips used in the ssd, as there was some discussion of this a year or so ago. It seems like the Air in this example is a 1 TB model, so shouldn’t suffer the same slowdown. Then I thought it might be the result of Apple’s firmware, and their insistence on guaranteeing the ssd actually flushes writes to the nand. Something which doesn’t actually happen on many ssds. Apple writes their own firmware for the shipping ssds to make sure Force Unit Access and F_FULLSYNC is honoured. The drawback of this is it can slow down writes.
Then I tested my 2018 Intel Mac Mini:
Hmmmm, why is my six year old Intel box destroying the latest Apple Silicon machines in random writes? I am puzzled.