I am setting up an external RAID 1 array using SSD drives on my late 2013 iMac. Originally was just going to use for expanded storage but since it's more protected with the RAID thinking of making it my startup drive via USB 3.0 cable. How do I designate the startup disk in Mojave or Catalina, and what about the idea?
iMac 21.5", macOS 10.14
You can select the external drive as the default by using Startup Disk in System Preferences.
If the external RAID is a hardware based solution and it does not require any drivers, then it might work. I don't know if the macOS installer will allow it or not.
If you are using software RAID, then you are going to have problems when you go to upgrade macOS to the next major version because macOS does not support bootable RAID volumes anymore. To upgrade macOS to the next version would require breaking & rebuilding the RAID or cloning.
You can select the external drive as the default by using Startup Disk in System Preferences.
If the external RAID is a hardware based solution and it does not require any drivers, then it might work. I don't know if the macOS installer will allow it or not.
If you are using software RAID, then you are going to have problems when you go to upgrade macOS to the next major version because macOS does not support bootable RAID volumes anymore. To upgrade macOS to the next version would require breaking & rebuilding the RAID or cloning.
Unless your external drive enclosure is rated USB 3 and the SSDs are rated SATA 3 (6GBps), you will not see much improvement in speed over your current internal drive. Internals in 21.5-inch iMacs, unless built to order with something better, are 5400rpm SATA 2 (3GBps) models. A USB 2 external enclosure with a max transfer rate of 480MBps will be a serious performance setback.
The fastest of these slow factory-installed internal mech drives have actual read/write speeds in the range of 90-100MBps. A USB3 enclosure with 6GBps SSDs is rated at up to 5GBps, and actuals will be about 400MBs. Nice boost.
To confirm your external drive going to be fast enough, open System Profiler and click "USB" in the left-hand Contents pane. If the drive is connected you will see this:
If you see the 5GBps speed and your SSDs are 6GBps models. you should see a decent performance boost if your intenal is purely mechanical.
Yes the Raid will be hw set. No special drivers. Might work.
can you make external drive your startup disk on iMac
