I just bought a MBP 13" mid 2014 with a 128 GB SSD. When doing a disk speed test with the Black Magic Design-app, I only get about 210 MB/s write and about 510-550 MB/s read.

All the benchmark videos I have seen using the same app all get about 310 MB/s write and up to 700 MB/s read.

Is there something wrong with my disk? The computer seems fine in daily use but I want the performance I paid for.


Well if it is not the state of you disk it could easily be just a different SSD vendor. Those figures you have provided are from testing SanDisk 128GB equipped ones.

Apple has many different vendors for same part and some SSD chipsets are faster at sequential than other. It might just be the case. Here is an article on similar discrepancy over 2013 and 2014 MBAs

For many years, Apple has used different suppliers for the solid-state drives (SSDs) in its MacBook Air models, with drive performance varying among manufacturer brands. A recent study by Macworld demonstrated rather dramatic differences in SSD read and write speeds between tested 2013 and 2014 models, but at the time it was unclear whether the poorer performance for the 2014 models was still simply due to drive brand variances or if there was something specific to the 2014 machines causing an overall degradation in performance.

If it is the case then what you can do is either sell it and find SanDisk equipped one or bring it back to Apple if you are in 14 days window (you would have to pay restocking fee though. No you can't claim that you are not getting performance you have paid for because Apple is only advertising its performance as “up to” figures)

On the other hand if you are not working with high def video on this machine and SSD I wouldn't bother since those sequential speeds are only good for that. And that tool is from company that is creating pricey tools for movie production btw.

  • 1
    Yeah this is what I have found out myself. It turns out I do have a Sandisk SSD and its probably healthy. I won't return it but rather wait for aftermarket disks and I´ll buy a bigger and faster one. Thanks. Jan 6 '15 at 12:17

No there is nothing wrong with the disk: - you can have another file size than what is used in the "specs" - you can have a rather full disk and the GarbageCollection was not fully done. Please let your computer sleep overnight, without any software running, this will help your GarbageCollection; make sure you have enough free disk space for the Garbage collection, let's say 20%.

  • Hi and thanks for the response! I'm pretty sure it has nothing to do with inadequate space on my SSD. Of the roughly 120 gig available I still have 68 gigs available. Jan 5 '15 at 18:03

Your Mac already has a disk read/write speeds report in the Activity Monitor.

Since it is a dynamic value you need to start a app that reads/writes to the disk, or use Terminal for that:

To test write speed:

time dd if=/dev/zero bs=1024k of=tstfile count=1024

In the output, you should look for something that looks like "bytes transferred in 16.546732 secs (519131791 bytes/sec)." Copy and paste the bytes/sec speed into Google to convert to MB/s (e.g. Google search for "519131791 bytes/s in megabytes/s").

To test read speed:

 dd if=tstfile bs=1024k of=/dev/null count=1024

sample from my Activity monitor:


  • Sorry, you can't really benchmark an SSD with youtube movie since bandwidth figures are quite different
    – iskra
    Jan 5 '15 at 23:33
  • @iskra so what do you recommend?
    – Ruskes
    Jan 6 '15 at 0:47
  • Blackmagic Disk Speed Test is pretty fine for testing sequential throughput of the disk. It is doing just about the same you are proposing to do manually.
    – iskra
    Jan 6 '15 at 1:04
  • @Buscar웃: Your little guide gave me the same results as black magic tbh. :) Jan 6 '15 at 12:16

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