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macuser453787

macrumors 6502a
Original poster
May 19, 2012
578
151
Galatians 3:13-14
Considering this card for my cMP 4,1 (5,1), but StarTech support can't confirm whether or not it will work in El Capitan. It's only officially supported up to Yosemite.

Anybody using this card in El Capitan?

Here's the broader goal: I'm looking for a USB 3 card that is reliable and supports booting in OS X without having to pay the price tag for this Sonnet card that I was originally looking at.

It would also be a plus to not have to hook up internal power to the card, as is the case with the StarTech card.

Suggestions?
 
Are there really no USB 3 cards that support booting in OS X?

There are no bootable USB 3 cards for the cMP. It has nothing to do with OS X.

It doesn't even have anything to do with Macs. These cards won't make old USB 2.0 PCs support bootable USB 3 either.
 
There are no bootable USB 3 cards for the cMP. It has nothing to do with OS X.

It doesn't even have anything to do with Macs. These cards won't make old USB 2.0 PCs support bootable USB 3 either.
Please pardon my ignorance concerning this topic, but what does this issue have to do with, since it doesn't have to do with OS X, or Macs, or PCs?

Why is it that USB 2.0 built into my cMP supports booting, and eSATA via PCIe supports booting, but USB3 via PCIe does not?
 
Please pardon my ignorance concerning this topic, but what does this issue have to do with, since it doesn't have to do with OS X, or Macs, or PCs?

Why is it that USB 2.0 built into my cMP supports booting, and eSATA via PCIe supports booting, but USB3 via PCIe does not?

Firmware.

The hardware in the computer needs software to run it. The default hardware in a computer runs from software that is embedded in the computer called firmware. The firmware typically only knows about the minimum default hardware and maybe some very common optional hardware.

So the firmware on a Mac or PC built with USB 2.0 and SATA will know how to run the USB 2.0 and SATA--it has to, or it wouldn't work. But if you later add a USB 3.0 card, the firmware has no idea what it is for or how to use it.

After the operating system starts, the operating system can load drivers that support all manner of additional hardware. It is only at this point that the USB 3.0 card starts to work, because there is now software that knows how to support it. The card is not working at boot time.

It is theoretically possible to get a USB 3.0 card working at boot time using some workarounds, but I've never seen anyone actually do it and report success. Here are the two methods I'm loosely aware of:
  • The Clover bootloader looks like it has USB 3.0 drivers built into its package. Perhaps installing Clover on a normal bootable partition would enable USB 3.0, then you could select your USB 3.0 drive to boot.
  • You can install OS X on a normal bootable partition. Just after it loads the drivers you need you can have it redirect and continue booting from the USB 3.0 drive. Instructions for this (sort of) are here.
Don't ask me how to make them work because I do not know. It's just theory.
 
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Firmware.

The hardware in the computer needs software to run it. The default hardware in a computer runs from software that is embedded in the computer called firmware. The firmware typically only knows about the minimum default hardware and maybe some very common optional hardware.

So the firmware on a Mac or PC built with USB 2.0 and SATA will know how to run the USB 2.0 and SATA--it has to, or it wouldn't work. But if you later add a USB 3.0 card, the firmware has no idea what it is for or how to use it.

After the operating system starts, the operating system can load drivers that support all manner of additional hardware. It is only at this point that the USB 3.0 card starts to work, because there is now software that knows how to support it. The card is not working at boot time.

It is theoretically possible to get a USB 3.0 card working at boot time using some workarounds, but I've never seen anyone actually do it and report success. Here are the two methods I'm loosely aware of:
  • The Clover bootloader looks like it has USB 3.0 drivers built into its package. Perhaps installing Clover on a normal bootable partition would enable USB 3.0, then you could select your USB 3.0 drive to boot.
  • You can install OS X on a normal bootable partition. Just after it loads the drivers you need you can have it redirect and continue booting from the USB 3.0 drive.
Don't ask me how to make them work because I do not know. It's just theory.

Ah, I see now. Yes, firmware. Didn't consider that. I'm generally aware of firmware's purpose, but thanks for the extended explanation.

Looks like I'll be getting the Sonnet card then, because I only have one available PCIe slot and I want to be able to have a 2nd external boot option aside from using the built-in USB 2.0 ports with a flash drive. At least with the Sonnet card I'll have my USB 3.0 ports + bootable eSATA. :)
 
I appreciate the info! Currently the Sonnet Tempo Duo is priced lower the the CalDigit, but I will keep this option in mind. :)

The USB controller on the Sonnet is internally PCIe x1 2.0. Maxes out around 340-350 MB/s.
The USB controller on the Caldigit is internally PCIe x2 2.0. Maxes out around 660-700 MB/s.

Useless details:
The large chip on each card close to the PCIe connector is a PCIe switch chip(like an Ethernet switch). It connects the 2-4 PCIe lanes from the slot to the 1-2 lanes each for the eSATA controller and the USB controller. Virtually all marketed for Mac PCIe cards that have bridge chips use a PLX(now Avago) PCIe 2.0 switch.

If that matters to you.
 
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