slow SSD on external Thunderbolt

Discussion in 'Mac Pro' started by austinpike, Jul 3, 2014.

  1. austinpike macrumors 6502

    Oct 5, 2008
    Have a new MacPro, two Seagate thunderbolt sleds, a 240GB Seagate 600 SSD and a 1TB Crucial M550 SSD. The Seagate performs as expected. The Crucial is cripplingly slow (like, progress bar says an hour to copy 5GB.)

    Things I've tried:
    • swapped sleds, drives, cables - no difference.
    • plug the Crucial into an internal sata port on another machine - performs at full speed.
    • connect the Crucial to the MacPro via a Seagate USB3 connector - performs at full USB3 speed.
    • reformat the Crucial to exFAT - performs at full speed on Thunderbolt.

    So, specifically the only "slow" condition is the Crucial formatted with MacOS Extended on Thunderbolt. Does anyone have any idea what could be going on here?

    If I need to leave it formatted exFAT to get the proper speed, is there any downside to that?
  2. stefanski macrumors member


    Apr 11, 2004
    Hm, I used to have Crucial SSDs and I had nothing but dramas with them in a MAC environment. Maybe check whether they released a new firmware which they seem to do frequently. I was able to sometimes solve the speed issues that way. exFat is just that. There's nothing bad about it other than that it's not a journaled file system and it won't offer any permissions the way you can set them on a Mac FS. The advantage being that you can use it on a windows machine if you ever have to share stuff via SSD.

    This may be useful as it also lists all the firmware updates:

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