On 4/14/2019 3:49 AM, James Linder wrote:
Hi I have a mid 2011 iMac. I setup a SSD on usb3 over thunderbolt. All good EXCEPT that it wont boot. Will boot on the usb2 ports but they are slower than usb3. I'm looking for a pointer or advice on how to boot on diskA say the internal disk, but run (root on) diskB I can't find a thunderbolt 1 disk or adapter Can anybody point me at where I could ask these sort of questions sorry for last-resort posting here Thanks James
Hi James, I want to try clarifying the hardware issues here, so that maybe you won't have to resort to straddling the internal drive and an external drive. From what I've gathered, I would be optimistic that there is at least one better arrangement than booting from USB 2 with your iMac. One option is FireWire 800, which is about twice as fast as USB 2 (and FireWire 400). If you find a FireWire 800 SSD, or an "enclosure" that you put your own SSD in, your iMac will almost certainly support booting from it. However, this option has become less worthwhile or future-proof due to FireWire being absent from recent Macs (which would require a Thunderbolt to FireWire adapter) and for being slow compared to Thunderbolt or USB 3. The other potential option is…Thunderbolt, but using a drive that connects directly to Thunderbolt, rather than through a USB 3 hub/dock. It's not clear to me whether your iMac can support booting from any given Thunderbolt drive or only certain ones (e.g. depending on whether the drive internally uses the newer PCIe/NVMe interface instead of the older SATA/AHCI interface; or what specific firmware and macOS versions your iMac is running), or none at all. I think that some Mac-oriented vendors like Sonnet or OWC might be more knowledgeable on questions like whether your model iMac will support booting from a particular Thunderbolt drive of theirs and under what conditions. Also, there *is* a way to connect your Thunderbolt 1 iMac to Thunderbolt 3 devices: Apple's bidirectional Thunderbolt 2 to 3 adapter, MMEL2AM/A. Some caveats include that the Thunderbolt 3 device must have a separate power source, the Mac must be running 10.12 Sierra or later, and of course it will only run up to Thunderbolt 1 speeds on your iMac. Hope this helps Christopher A. Chavez
