Unable to Install Centos 7.7.1908 with RAID1 on 400GB SSDs: "sdb may not have enough space for grub 2 to embed core.img when using the xfs"

[keennay]

sdb may not have enough space for grub 2 to embed core.img when using the xfs file system on mdarray

The above is the error I receive when attempting to install Centos 7.7.1908 from a USB drive (BIOS boot) onto two 400GB SAS SSDs and configure the boot, root, and swap directories as RAID1. The target device is a Dell PowerEdge 720 at my physical location.

I however do not see this problem when attempting to install on 1.92TB SSDs laying around, though I only have a few of those and more of the 400GB SSDs. At first I thought this was a problem with my disk capacity, but here is one YouTube video where the uploader had no issues setting up the OS in a RAID 1 setup with 20GB drives:

Here's my screen:

 

[dos2unix]

You have to either have a /biosboot partition (about 2 MiB) for legacy BIOS... or
you have to have /efiboot partition (about 200 MiB) for UEFI.
One of these two partitions is required!
Everything else is fine. I would recommend making boot at least 2 GiB.

There is also an "auto create" that will automatically make all the partitions for you.

Mine looks like this.

You don't need /var and /usr on their own partitions (I just like it this way)
But everything else is pretty much required.