Using boot0 to redirect booting to another disk?

[José María Alcaide]

(I previously sent this post from the wrong email address, so I'm sending it again. My apologies if it shows twice.)
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Hi.

I have an HP Proliant Microserver Gen8. Nice machine but picky BIOS. When its hard disk controller is configured in SATA AHCI mode, there is no way to choose the boot disk among those connected to the SATA ports. I have four HDD attached to the backplane, and another drive connected to a fifth SATA port originally intended for an optical drive. The four HDD are arranged in a RAIDZ. Currently the machine is booting from an USB flash device, but I would like to boot the FreeBSD installed on fifth drive. The disk controller sees and reports the five disks just fine, but as I said above, there is no way to choose the fifth disk as a boot device.

I wondered whether I could use boot0 to redirect the boot from a USB flash device (pendrive or, still better, a microSD) to the fifth drive. The idea comes from the fact that boot0 shows a "F5 - Drive 2" option when it detects more than one drive. I tried to understand how boot0 works reading its source code, and I experimented with the boot0cfg's "-d disk" and "-o setdrv" options, to no avail. So I decided to ask for help. :)

Is that possible? Any help will be greatly appreciated.


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Jose M. Alcaide