Find Out How Fast Your SSD Or Hard Drive Really Is [OS X Tips]

Find Out How Fast Your SSD Or Hard Drive Really Is [OS X Tips]

Geeky, yes. Cool? Yes, again.

Sometimes, it’s just fun to compare scores with your friends. Without the urge to compete, we wouldn’t have sports, national videogame competitions, or reality television. Now there’s a new way to measure up against those around you – Solid State Drive (SSD) speed.

Ok, so it’s not really a thing, but here’s how you can benchmark your own SSD to compare it with other SSD devices, if you need to know how much faster one computer you own is than another. In fact, it’s a ton of fun to compare the speed of an SSD, say in this here Macbook Air, and that of a hard drive, like in my Mac Mini. Here’s how.

Launch Terminal from the Utilities folder, which is located in the Applications folder. Copy and paste the following into the Terminal once it’s running:

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

This command measures write speed of your storage device, be it an SSD or a more traditional Hard Disc. The output will look something like this:

1024+0 records in
1024+0 records out
1073741824 bytes transferred in 4.675983 secs (229629114 bytes/sec)

real 0m4.683s
user 0m0.003s
sys 0m0.781s

See the bytes/sec number? You can change that to megabytes per second with a quick Google search. Search for 229629114 bytes in megabytes, and you’ll get a more comprehensible – easier to remember, at least – number. In this example, this translates to 218.991 Mb/sec. I’m gonna call it 219.

To test the speed your HD or SSD reads info, paste the following command into the Terminal app:

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

The output is a little less verbose in this case, giving something like the following:

1024+0 records in
1024+0 records out
1073741824 bytes transferred in 7.575844 secs (141732303 bytes/sec)

This, according to my Google search, is 135.166 Megabytes/sec, rounded to 135 Mb/Sec. So, my Macbook Air has an SSD inside it, with 219 Mb/s write speed and a 135 Mb/s read speed. I can now take this number with me when shopping for a faster SSD drive, or check my other Macs around the house, to see which one is faster. Or, I guess, brag on the internet about how much faster my SSD is than anyone else’s. Which, you know, I’m not gonna do.

Got an OS X tip? Need help troubleshooting OS X? (sorry, you need Javascript to see this e-mail address)or leave a comment below.

  • steveyknight

    250MB/s read, 250MB/s write from an external Thunderbolt SSD drive; didn’t wan to open my iMac and fit an internal, not bad.

  • ramunasbl

    hm ….
    my stripped partition of 3x3GB hdd on Mac Pro showed: 247Mb – write and 4738Mb – read
    SSD on the same computer: 249Mb – write and 4848Mb – read.
    Can the difference between read and write be so huge?

    P.S. command
    rm tstfile
    after test is done might be helpful as the test creates 1 Gigabyte file named “tstfile”

  • jonathann92

    my write is about 95 MB/s and my read is about 3000 MB/s ? How is this possible?

    screenshot : http://imgur.com/FAaix

    It might also be note worthy that I have a crucial m4 256GB SSD and a seagate momentus xt 500GB Hybrid in my MBP.

    How would I choose which drive to test?

  • Oleguer Txdr

    45MB/s write, 5.437MB/s read? Is that normal? hahaha (haven’t messed with any zero)

  • ramunasbl

    my write is about 95 MB/s and my read is about 3000 MB/s ? How is this possible?
    < ...>
    How would I choose which drive to test?

    in terminal cd to the disk’s you want to test directory you have rights to create files and perform the test. As the test creates the file on the location you are performing the test.

    i.e.
    cd /Volumes/MyAnotherDisk/tmp
    presume MyAnotherDisk is the another existent disk name and tmp is directory on that disk your user is able to write in.

  • Den Mauro

    Last login: Mon Jul 23 17:31:57 on console
    MacBook-Pro-di-danny-mauro:~ Den$ time dd if=/dev/zero bs=1024k of=tstfile count=1024

    1024+0 records in
    1024+0 records out
    1073741824 bytes transferred in 2.005652 secs (535358003 bytes/sec)

    real 0m2.025s
    user 0m0.004s
    sys 0m0.568s
    MacBook-Pro-di-danny-mauro:~ Den$
    MacBook-Pro-di-danny-mauro:~ Den$
    MacBook-Pro-di-danny-mauro:~ Den$ dd if=tstfile bs=1024k of=/dev/null count=1024
    1024+0 records in
    1024+0 records out
    1073741824 bytes transferred in 0.189592 secs (5663430563 bytes/sec)
    MacBook-Pro-di-danny-mauro:~ Den$
    MacBook-Pro-di-danny-mauro:~ Den$
    not bad!

  • stueee123

    Blackmagic Disk Speed Test performs the same function in a much more readable way…its free on the App Store. I get around 402 MB/s write and 445.5 MB/s read on my rMBP.

  • jonathann92
    my write is about 95 MB/s and my read is about 3000 MB/s ? How is this possible?
    < ...>
    How would I choose which drive to test?

    in terminal cd to the disk’s you want to test directory you have rights to create files and perform the test. As the test creates the file on the location you are performing the test.

    i.e.
    cd /Volumes/MyAnotherDisk/tmp
    presume MyAnotherDisk is the another existent disk name and tmp is directory on that disk your user is able to write in.

    Thanks for that information! But this still doesn’t explain why my read speeds are so high, nearly 3GB/s.

    My SSD holds the OS and the applications, named Macintosh HD. My hybrid holds my home folder, named HD.

    Heres a screen shot of my terminal again : http://imgur.com/jQD56

  • john_holley

    I have the same comment on the read speed. Getting for 396 Mb/sec for write and 6187 Mb/sec for read!

    time dd if=/dev/zero bs=1024k of=tstfile count=1024
    1024+0 records in
    1024+0 records out
    1073741824 bytes transferred in 2.582577 secs (415763723 bytes/sec)

    real 0m2.652s
    user 0m0.003s
    sys 0m0.893s

    time dd if=tstfile bs=1024k of=/dev/null count=1024
    1024+0 records in
    1024+0 records out
    1073741824 bytes transferred in 0.165495 secs (6488055856 bytes/sec)

    real 0m0.168s
    user 0m0.001s
    sys 0m0.166s

About the author

Rob LeFebvreAnchorage, Alaska-based freelance writer and editor Rob LeFebvre has contributed to various tech, gaming and iOS sites, including 148Apps, Creative Screenwriting, Shelf-Awareness, VentureBeat, and Paste Magazine. Feel free to find Rob on Twitter @roblef, and send him a cookie once in a while; he'll really appreciate it.

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