Title: FreeBSD 11 and Perc H720P Mini raid controller
Author: Solène
Date: 25 May 2016
Tags: freebsd11 hardware
Description: 

I had a problem with my 3 latests R430 Dell server which all have a
PERC H730P Mini raid controller. The installer could barely works and
slowly, and 2 servers were booting and crashing with FS corruption
while the latest just didn't boot and the raid was cleared.

It is a problem with a driver of the raid controller. I don't
understand exatly the problem but I found a fix.

From man page mfi(4)

attaching
    to a card.  By default the driver will attach to all known cards
with
    high probe priority.  If the tunable hw.mfi.mrsas_enable is set to
1,
    then the driver will reduce its probe priority to allow mrsas to
attach
    to the card instead of mfi.

In order to install the system, you have to set
**hw.mfi.mrsas_enable=1** on the install media, and set this on the
installed system before booting it.

There are two ways for that:

- if you use a usb media, you can mount it and edit /boot/loader.conf
  and add `hw.mfi.mrsas_enable=1`
- at the boot screen with the logo freebsd, choose **3) Espace to boot
  prompt**, type `set hw.mfi.mrsas_enable=1` and **boot**

You will have to edit /boot/loader.conf to add the line on the
installed system from the live system of the installer.

I have been struggling a long before understanding the problem. I hope
this message could save time to somebody else.