Using only device drivers that are stored on your Mac's firmware chip, the firmware will scan all of your SATA, PCI, USB, and Thunderbolt busses for hard drive devices, then read those hard drive volume headers to determine if a macOS system is available on each volume.
When you boot your Mac while holding down the Option key, the Mac Startup Manager will display a list of available startup devices. Sometimes the Mac's firmware cannot detect your backup device
Cloning macOS System volumes with Apple Software Restore.Some Big Sur startup volumes don’t appear in the Startup Disk Preference Pane.If that does not produce a bootable device, then the device is not suitable for functioning as a bootable device on your Mac.
If that does not produce a bootable volume, and if you have exhausted the Firmware Discoverability Troubleshooting steps below, then we recommend that you install macOS onto the backup. When you make a backup of a Big Sur startup disk with CCC 5.1.23 or later, CCC will automatically use Apple's proprietary APFS replication utility (ASR) to make an exact copy of the source. This volume is cryptographically sealed, and that seal can only be applied by Apple ordinary copies of the System volume are non-bootable without Apple's seal.
Starting in macOS Big Sur, the system now resides on a "Signed System Volume". MacOS 11, "Big Sur" bootability troubleshooting
Before you ask for help, please try the troubleshooting steps below. A human must always be present to hand-enter the option 4 on the boot override menu.We're happy to help you troubleshoot your bootability problems. This is a problem whenever this computer reboots, including after installing updates. If I select 4) One time boot to HDD, it then boots WIN SBS.Īs you can imagine, this is quite a problem for a SBS server that is suposed to operate more-or-less unattended. The only way to get it to boot from the hard drive is to hit F11 (see bootStart image), and then I get a menu giving me one-time boot options (see bootOverride image). When it fails to boot from NIC, it restarts the computer and goes through the whole sequence again. It tries the CD, USB, Hard Drive (doesn't boot from that!), then NIC. See the bootStart image:Īfter running through the power-up diagnostics, it then attempts to boot (see bootsequence image). It has 24BG memory, 2 quad processors and a Raid 1. I don't believe this has always been true it seems like something that has developed lately. This computer will not boot from the hard drive upon power-up. I have an HP Proliant server running Windows SBS 2008.