Currently Being ModeratedAug 21, 2011 7:32 PM (in response to nightotter)
If you have narrowed it down to the hub then that is what you should be troubleshooting. If the drives are getting their power from the hub that might be the issue. Also when you're posting please give specifics like makes and models otherwise we're shooting in the dark. If you are using WD drives that could be the problem there too, they tend to have a wide variety of issues with OS X.
Currently Being ModeratedAug 21, 2011 7:34 PM (in response to nightotter)
Do the hubs have their own power supply or are they powered by the Mac's USB port? I'd guess that could be a problem because the USB port may not have enough power for the hub and to read/write the drive(s)?
Currently Being ModeratedAug 21, 2011 8:04 PM (in response to nightotter)
Thasnks for the ptompt reply folks. The HUB is a 4-port Belkin, with a power supply. The Hard Drive are each 1 TB. The run on the power from the USB. They are a Seagate and a Toshiba. Now that you both mention the power issue, maybe that is the problem. But it has mounted before. Sometime it's work and sometimes it doesn't. My Flash Drive will show up as will my iPhone or iPad or iPods. But the Hard Drives are having a problem. It seems very sensitive. Sometime when I dismount the Flash Drive, the Hard Drive will dismount too, like it was hanging on a thread and the dismounting of the Flash Drive knocked it off.
I was hoping the Disk Utility might have some scanning feature. I remember WAY BACK in the old OS (9 and before) there was a program that scanned for connected devices. I was hoping there might be something like that which could help.
Currently Being ModeratedAug 21, 2011 8:09 PM (in response to nightotter)
The issue is the EHD's are not getting enough power. Going forward never buy EHD's unless they have their own power supply. I would recommend either connecting directly to the iMac or replacing them with higher quality devices. The EHD's I like to recommend are:
All are similar in quality and features. Yes they're probably more money that what you paid however they're worth it. I use the LaCie's however I wouldn't hesitate to use the OWC or G-Tech's either.
Currently Being ModeratedAug 21, 2011 8:26 PM (in response to nightotter)
My Flash Drive will show up as will my iPhone or iPad or iPods.
Those will show up because they don't require that much power - but 1 TB hard drives are another matter. Aside from the power issue, I'd also seriously consider drives which have Firewire as that is considerably faster than USB. And, I agree with Roger on his recommendations - I have one OWC and two LaCie's - all are Firewire (actually they all have FW 400 + 800, USB, and eSata ports) and all have their own power supply.
Currently Being ModeratedAug 21, 2011 8:31 PM (in response to nightotter)
Thanks ot you all, you were all corrent, great community. I will use the present HD's as offline backups and pick up 3TB linked above. Thanks again! Otto.
Currently Being ModeratedAug 21, 2011 10:48 PM (in response to nightotter)
You might also take a close look at your powered hub. Some of those have a small selector switch on them somewhere which allows settiing it to use bus or self power. If yours has such a switch, make sure it is not set to "bus".
Currently Being ModeratedAug 22, 2011 7:01 AM (in response to Don Archibald)
Thanks Don. My HUB doesn't have that switch, but I will look for one in the future. Otto
Currently Being ModeratedJan 20, 2014 8:21 PM (in response to nightotter)
I know this is an old post, but I have a similar and somehow different problem.
My new WD My Book Studio 3TB drive works well through a powered USB3 hub when the OS is freshly booted. However, once unmounted and unplugged the USB3 hub, it won't mount by plugging back the hub without rebooting. Does anybody have similar experience?