FreeBSD Administration

MFI to MRSAS FreeBSD Driver

I have a Dell FreeBSD server with an H730/P LSI MegaRaid controller. When I first installed FreeBSD on it, I started to see all kind of errors from the drives (this was in a ZFS install). It turned out to be that the older MFI driver was getting detected first.

The LSI MegaRaid MFI driver is really designed for the older controllers. This driver is simpler and also doesn’t have Trim support for SSD drives. There is a newer driver (MRSAS) in FreeBSD designed for the newer LSI MegaRaid controllers, of which the H730/P is one of them). The problem is that the newer controllers are backwards (sort of) compatible to the older controllers and the old MFI drivers has priority to load first.

How to prioritize the MRSAS driver.

In /boot/loader.conf set the following two lines:


Then reboot. This should load the mrsas driver instead and the errors should go away.

If you run ZFS then make sure to ask ZFS to check the file system and clean things up just incase there are any lingering errors:

# zpool scrub zroot

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