64G SanDisk Extreme USB 3.0 Flash Drive

Perhaps you must install a driver for your 2 USB-sticks.

When you go to the Apple menu > About this Mac > More Information > System Report and then to USB (with the SanDisk USB stick connected), do you see the device being recognized at all?

Another place to look would be Disk Utility. Does it recognize the stick and is there a partition with a supported file system on it?

I remember there used to be a problem with large FAT32 volumes taking a long time to be recognized in OS X. To be honest, I'm not sure whether this is still true or has been fixed in the meantime. But it might be worth a shot to delete the stick using Disk Utility (be sure to select the stick and not the partition on it) and re-format with Mac OS Extended (journaled). Just to see whether it makes a difference.

Of course, you will probably want to re-format with FAT32 again after that, because otherwise you wouldn't be able to exchange data with PC users.

Jep i have the exact same problem with the Sandisk Extreme 64GGB USB 3.0... It works on my Windows 7 Computer, but on my Retina Macbook Pro the finder always freezes...

Same here. I bought 2 Sandisk extreme 64GB USB 3.0 last week and can't get them to work, they freeze Finder, do not unmount at all or only after a very long period in Disk Utility. Also, I can't copy any files onto them in OSX, it takes ages with zero progress. Trying to reformat with Disk Utility won't work (can't unmount the drive and/or can't format it). Seems to be rather hopeless. I only managed to re-format them under W7 as exfat partion, but still does not work in OSX.

Interestingly enough, I also bought a Sony USB 3.0 64GB stick, no problems here, neither with OSX (Mountain Lion) nor with W7. Works just fine and extremely fast.

It looks as if you've narrowed down the problem, then, to a specific USB 3.0 flash device. There have been numerous reports of the USB 3.0 ports on the 2012 models not playing nice with some USB 3.0 devices. Advertise the fact that the Sony stick works fine - maybe those having trouble with the Sandisk extreme storage devices can return them for the Sony.

Is this the one you bought that works?

Clinton

Yes, this is the flash drive I described working fine.

I have same problem with this sandisk extreme USB 3.0 64g flash drive!!!!!!😠😠

I can't ERASE it in Disk Uility and always show up "unable to write to the last block of the device"~~~

What can I do NOW? THX~~~~

@ 。T_T。

idk if this is right or if its been mentioned already, not bothered to read the whole thread, BUT ...

i heard the rMBP USB ports are not powerful enough to power some usb drives

not sure about this or if its true 😕 seems a bit strange for one of the most powerful laptops

Any update on what's going on here? Is it only the 64gb version or the 32gb one as well?

Ok I brought the USB Stick back and I they gave me a new one.

Instead of sticking the new stick in my Retina Macbook, I formated it FIRST on my Windows 7 Machine (normal FAT). Now it works perfectly on my Retina! I don't know if this is the solution, but it worked for me. Maybe the preinstalled software on the stick is causing problems, I don't know...?

I've been having exactly the same problems with the SANDISK extrem 64GB memory stick.

I've tried formatting it in DOS (windows 7 version) and, in case it was a USB 3.0 problem, I've tried initialising it on my old macbook with USB 2.0.

It has problems unmounting the flash drive, or, if it gets past that, I get the 'Unable to write to the last blck of he device' error. I've now had that error with USB 2.0 when trying to partition it as a Mac OS journaled device with a GUID boot area.

It looks as if I'm going to have to take it back to the shop.

Unless, that is, there's some handy command line utility that can zap the drive into submission.

I'm trying to use Disk Utility to copy a bootable image to the drive to see if that gets around it.

Any suggestions?