USB3-->USB2 Woes
August 1, 2012 10:08 PM

I'm getting awful speeds transferring to a USB 3 external drive from my USB 2 Macbook Pro.

I have a 2009 era Macbook Pro with firewire 800 and USB 2. I bought a Seagate Expansion 1 TB USB 3.0 Desktop External Hard Drive for $90. And, my god, it's averaging 5mb/sec transfer!

It's not a huge big deal, since I will only use this drive every few months or so (for infrequent off-site backup). And I can let the job run overnight. But....ugh.

I own a (smaller) USB 2 drive, and it seems to transfer reasonably quickly....a lot better than 5mb/sec. Is there an intrinsic problem using USB 3 drives with USB 2 computers (Seagate claims compatibility for both)? If not, is there anything I need to check? (I did format the drive to extended/journaled). One solution would to return this drive and try to buy another USB 2 drive....if I can find one.....
posted by Quisp Lover to Computers & Internet (9 answers total)
It may simply be a slow drive. A slow drive with a fast interface will still transfer slowly.
posted by Chocolate Pickle at 10:11 PM on August 1, 2012


No major speed complaints on Amazon, with tons and tons of reviews. There are, however, some serious complaints very specifically about speeds using USB2 computers.

And I don't think there's a drive made in the past decade that's supposed to transfer @ 5mb/sec. That's not slow, it's glacial.
posted by Quisp Lover at 10:16 PM on August 1, 2012


Also, I'd hate to buy a USB2 drive 'cuz I may be updating my Mac. OTOH, a USB3 Mac should(?) hopefully get the same transfer speed from a USB2 drive, even if the same's not true with a USB2 Mac and a USB3 drive! :)
posted by Quisp Lover at 10:20 PM on August 1, 2012


Here's one anecdotal datapoint: I was recently using a USB 3.0 drive on a 2.0 system and I was getting around 15 megabytes/second out of it. On a 3.0-capable Mac, I got about 40-50.

Perhaps you should get a Seagate GoFlex drive, and use the GoFlex FW800 adapter with your current Mac. And if you upgrade the Mac, you can use the USB 3.0 adapter.
posted by zsazsa at 10:24 PM on August 1, 2012


Could you get a USB 3 ExpressCard/34 for your MBP? You'll get a much faster connection that way, for very little extra cash.
posted by Blazecock Pileon at 10:24 PM on August 1, 2012


You might have a MBP from when Apple switched from ExpressCard/34 to a SD camera media slot. But if you have the ExpressCard slot, use it! It's very fast.
posted by Blazecock Pileon at 10:29 PM on August 1, 2012


zsazsa : I saw that option, but I'm kind of annoyed at Seagate right now. They did, after all, promise USB2 compatability!

BP - Yeah, I have a freakin' SD camera media slot. Alas.
posted by Quisp Lover at 10:33 PM on August 1, 2012


A USB2 computer should be capable of getting USB2 speeds out of a USB3 drive. All the new high speed USB3 stuff is actually on new pins that were added to the the USB connector. (For example, on this micro USB3.0 cable, you can see the additional pins.)

There might be an issue where the controller on the disk is expecting USB3 so it's tuned to that. When you use USB2 everything is off kilter and isn't setup for high speed.

I'm not sure where this leaves you though. USB3 is *supposed* to just work with USB2 equipment. Can you try it on a USB3 computer and see if there is a problem with the drive?
posted by pknodle at 10:34 PM on August 1, 2012


I'd send it back. Given the other reviews it's pretty clear Seagate screwed up. They should eat the price of the drive.

If you can, get a USB/Firewire drive. Firewire is still a good interconnect standard.
posted by chairface at 7:45 AM on August 2, 2012


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