create a small SD-boot to sda

Johan Nilsson · 2026-04-22T10:33:59Z

Hey

Installed Armbian (Ubuntu-noble) with XFCE desktop on an HDD(sda) from SD-card, so I need to have an SD-card in my orange pi zero 2w. I wonder if I can move /boot to an another smaller SD-card? Or do I also need an "mbr" or someting also there u-boot are?

/Cheers

eselarm · 2026-04-22T11:40:39Z

I assume OPi02w has no on-board storage, so it only is the bootcode in ROM, and that reads U-Boot binary blob from fixed sector offset location on the SD-card. It does not even need a MBR-table or GPT and it is not in a partition, so you won't see it. Only if you use dd to read (or write/wipe) that data you will know. See how U-Boot needs to be written for your OPi02w, then you will understand.

If the U-Boot is build to initialize the USB and HDD, you do not need /boot partition on the SD-card. But I do not know that. Not all USB-SATA chipset drivers are in U-Boot, so if not, you indeed need a boot partition on de SD-card where kernel initrd DTB are, those should understand USB-SATA chips and so see the rootfs on HDD.

Johan Nilsson · 2026-04-22T13:18:44Z

Ok. Thanks. dd copie the blob. It has SPI or a little memory, but as I understand it could be a problem, so it easier to use SD as boot-disk.

eselarm · 2026-04-22T13:56:07Z

What you prefer or think is best. An extra boot partition is more flexible as it is an extra 'boot-stage' sort of, and normal computers that use UEFI anyway need also a FAT formatted bootpartition besides 1 or more rootfs for (multiple) OS. So not a bad approach to have separate boot partition an if on SD-card, is removable, so is flexible in case of trouble and/or testing things.