Boot from USB and still have access to RAID?

I have an older computer, a Dell Precision notebook.
It has two hard drives in it that are RAIDed together (stripe 0 I think, for speed).
I am trying to boot to a USB so I can scan the whole system for malware:
https://www.lifewire.com/free-bootable-antivirus-tools-2625785
However, I have tried several of the suggestions but none of them find my hard drive once booted via USB.
The RAID drive is loaded and passed the POST test before even booting from USB, shouldn't it be able to read from the RAID drive?

There may be additional options to scan for malware:

1) Use Windows defender offline
2) Temporarily turn off RAID > boot to USB scan > restart RAID after scan
3) Use malware scans that do not require boot start