Jump to content

OpenCore 0.6.7 USB drive + Big Sur installer does not see existing HDD volumes

3 posts in this topic

Recommended Posts


I was able to successfully install Big Sur on P7H55M-LX computer.

The computer has Xeon x3470 CPU which lacks RDRAND instruction what forced me to use HfsPlusLegacy.efi driver to read/write on HDD.

First none critical issue is that when OpenCore menu displayed on the screen to move from one boot option to other takes about 1.5-2 seconds (lag in response on keyboard key press).

Now main issue: I attempted to boot same system from same OpenCore USB drive with other HDD preinstalled with Catalina. NOTE: this HDD EFI partition has CLOVER bootloader which present but not used during boot from OpenCore USB drive.

With assistance OpenCore I can boot Big Sur installer from second USB drive and reach a point where I start Big Sur installation and an installation volume should be selected. But Big Sur installer does not see existing volumes, disktool sees whole disk but not existing volumes.

Is it known issue?

My guess is that HfsPlusLegacy.efi driver is not able/capable to see volumes created with other driver.

Can somebody verify and confirm my understanding of the issue?

Thank you,

I use OpenCore with legacy settings to run Big Sur on my old non-UEFI Core2Duo Dell Vostro 200 desktop computer. I had no such issue when installing Big Sur with OC on the SSD which had existing High Sierra and Catalina installations that I ran with Clover.


What you describe is not a known issue to me and the HfsPlusLegacy driver had no issue detecting existing APFS volumes on a disk as far as I'm concerned. I'd say your problems are more related to your config than the HfsPlusLegacy driver.

If you are talking about the Big Sur installer itself, then it isn't an issue with EFI drivers at all. Those just help OpenCore read/find volumes to boot, and be able to boot those. Once your in the installer, it's using all of Apple's drivers to do everything.


That's weird that it can't see any of the volumes on the drives though, especially if it can see the disks. Idk why that would be.


Are you using DEBUG OpenCore right now with a lot of logging enabled? That could explain the slow speeds within the OC picker.

  • Create New...