MRSAS(4) FreeBSD Kernel Interfaces Manual MRSAS(4)
NAME
mrsas - Broadcom/LSI MegaRAID 6/12Gb/s SAS+SATA RAID controller driver
SYNOPSIS
device pci
device mrsas
In loader.conf(5):
mrsas_load="YES"
In sysctl.conf(5):
dev.mrsas.X.disable_ocr
dev.mrsas.X.fw_outstanding
dev.mrsas.X.mrsas_fw_fault_check_delay
dev.mrsas.X.mrsas_io_timeout
hw.mrsas.X.debug_level
DESCRIPTION
The mrsas driver will detect Broadcom/LSI's 6Gb/s and 12Gb/s PCI Express
SAS/SATA/NVMe RAID controllers. A disk (virtual disk/physical disk)
attached to the mrsas driver will be visible to the user through
camcontrol(8) as /dev/da? device nodes. A simple management interface is
also provided per-controller via the /dev/mrsas? device node.
The mrsas name is derived from the phrase "MegaRAID SAS HBA", which is
substantially different than the old "MegaRAID" Driver mfi(4) which does
not connect targets to the cam(4) layer and thus requires a new driver
which attaches targets to the cam(4) layer. Older MegaRAID controllers
are supported by mfi(4) and will not work with mrsas, but both the mfi(4)
and mrsas drivers can detect and manage the Broadcom/LSI MegaRAID SAS
2208/2308/3008/3108 series of controllers.
The device.hints(5) option is provided to tune the mrsas driver's
behavior for LSI MegaRAID SAS 2208/2308/3008/3108 controllers. By
default, the mfi(4) driver will detect these controllers. See the
PRIORITY section to know more about driver priority for MR-Fusion
devices.
mrsas will provide a priority of (-30) (between BUS_PROBE_DEFAULT and
BUS_PROBE_LOW_PRIORITY) at probe call for device id's 0x005B, 0x005D, and
0x005F so that mrsas does not take control of these devices without user
intervention.
Solid-state drives (SSD) get ATA TRIM support with mrsas if underlying
adapter allows it. This may require configuring SSD as Non-RAID drive
rather then JBOD virtual mode.
HARDWARE
The mrsas driver supports the following Broadcom/LSI SATA/SAS RAID
controllers:
Controller Chip Speed
Broadcom SAS3916 Aero 12Gb/s
Broadcom SAS3908 Aero 12Gb/s
LSI MegaRAID SAS 9380 Invader/Fury 12Gb/s
LSI MegaRAID SAS 9361 Invader/Fury 12Gb/s
LSI MegaRAID SAS 9341 Invader/Fury 12Gb/s
LSI MegaRAID SAS 9286 Thunderbolt 6Gb/s
LSI MegaRAID SAS 9285 Thunderbolt 6Gb/s
LSI MegaRAID SAS 9272 Thunderbolt 6Gb/s
LSI MegaRAID SAS 9271 Thunderbolt 6Gb/s
LSI MegaRAID SAS 9270 Thunderbolt 6Gb/s
LSI MegaRAID SAS 9267 Thunderbolt 6Gb/s
LSI MegaRAID SAS 9266 Thunderbolt 6Gb/s
LSI MegaRAID SAS 9265 Thunderbolt 6Gb/s
LSI SAS 3108 12Gb/s
LSI SAS 3008 12Gb/s
LSI SAS 2308 6Gb/s
LSI SAS 2208 6Gb/s
DELL PERC H830 Invader/Fury 12Gb/s
DELL PERC H810 Thunderbolt 6Gb/s
DELL PERC H730/P Invader/Fury 12Gb/s
DELL PERC H710/P Thunderbolt 6Gb/s
DELL PERC H330 Invader/Fury 12Gb/s
Fujitsu D3116 Thunderbolt 6Gb/s
CONFIGURATION
To disable Online Controller Reset(OCR) for a specific mrsas driver
instance, set the following tunable value in loader.conf(5):
dev.mrsas.X.disable_ocr=1
where X is the adapter number.
To change the I/O timeout value for a specific mrsas driver instance, set
the following tunable value in loader.conf(5):
dev.mrsas.X.mrsas_io_timeout=NNNNNN
where NNNNNN is the timeout value in milli-seconds.
To change the firmware fault check timer value for a specific mrsas
driver instance, set the following tunable value in loader.conf(5):
dev.mrsas.X.mrsas_fw_fault_check_delay=NN
where NN is the fault check delay value in seconds.
The current number of active I/O commands is shown in the
dev.mrsas.X.fw_outstanding sysctl(8) variable.
DEBUGGING
To enable debugging prints from the mrsas driver, set the
hw.mrsas.X.debug_level variable, where X is the adapter number, either in
loader.conf(5) or via sysctl(8). The following bits have the described
effects:
0x01 Enable informational prints.
0x02 Enable tracing prints.
0x04 Enable prints for driver faults.
0x08 Enable prints for OCR and I/O timeout.
0x10 Enable prints for AEN events.
PRIORITY
The mrsas driver will always set a default (-30) priority in the PCI
subsystem for selection of MR-Fusion cards. (It is between
BUS_PROBE_DEFAULT and BUS_PROBE_LOW_PRIORITY). MR-Fusion Controllers
include all cards with the Device IDs - 0x005B, 0x005D, 0x005F.
The mfi(4) driver will set a priority of either BUS_PROBE_DEFAULT or
BUS_PROBE_LOW_PRIORITY (depending on the device.hints setting) in the PCI
subsystem for selection of MR-Fusion cards. With the above design in
place, the mfi(4) driver will attach to a MR-Fusion card given that it
has a higher priority than mrsas.
Using /boot/device.hints (as mentioned below), the user can provide a
preference for the mrsas driver to detect a MR-Fusion card instead of the
mfi(4) driver.
hw.mfi.mrsas_enable="1"
At boot time, the mfi(4) driver will get priority to detect MR-Fusion
controllers by default. Before changing this default driver selection
policy, LSI advises users to understand how the driver selection policy
works. LSI's policy is to provide priority to the mfi(4) driver to
detect MR-Fusion cards, but allow for the ability to choose the mrsas
driver to detect MR-Fusion cards.
LSI recommends setting hw.mfi.mrsas_enable="0" for customers who are
using the older mfi(4) driver and do not want to switch to mrsas. For
those using a MR-Fusion controller for the first time, LSI recommends
using the mrsas driver and setting hw.mfi.mrsas_enable="1".
Changing the default behavior is well tested under most conditions, but
unexpected behavior may pop up if more complex and unrealistic operations
are executed by switching between the mfi(4) and mrsas drivers for MR-
Fusion. Switching drivers is designed to happen only one time. Although
multiple switching is possible, it is not recommended. The user should
decide from boot which driver they want to use for the MR-Fusion card.
The user may see different device names when switching from mfi(4) to
mrsas. This behavior works as intended and the user needs to change the
fstab(5) entry manually if they are doing any experiments with mfi(4) and
mrsas interoperability.
FILES
/dev/da? array/logical disk interface
/dev/mrsas? management interface
SEE ALSO
cam(4), mfi(4), pci(4), device.hints(5), camcontrol(8)
HISTORY
The mrsas driver first appeared in FreeBSD 10.1.
mfi Driver: mfi(4) is the old FreeBSD driver which started with support
for Gen-1 Controllers and was extended to support up to MR-Fusion (Device
ID = 0x005B, 0x005D, 0x005F).
mrsas Driver: mrsas is the new driver reworked by LSI which supports
Thunderbolt and onward products. The SAS+SATA RAID controller with
device id 0x005B is referred to as the Thunderbolt controller throughout
this man page.
cam aware HBA drivers: FreeBSD has a cam(4) layer which attaches storage
devices and provides a common access mechanism to storage controllers and
attached devices. The mrsas driver is cam(4) aware and devices
associated with mrsas can be seen using camcontrol(8). The mfi(4) driver
does not understand the cam(4) layer and it directly associates storage
disks to the block layer.
Thunderbolt Controller: This is the 6Gb/s MegaRAID HBA card which has
device id 0x005B.
Invader Controller: This is 12Gb/s MegaRAID HBA card which has device id
0x005D.
Fury Controller: This is the 12Gb/s MegaRAID HBA card which has device id
0x005F.
AUTHORS
The mrsas driver and this manual page were written by Kashyap Desai
<Kashyap.Desai@lsi.com>.
CAVEATS
The mrsas driver exposes devices as /dev/da?, whereas mfi(4) exposes
devices as /dev/mfid?.
mrsas does not support the Linux Emulator Interface, mfiutil(8), or
device name aliases for switching drivers without editing fstab(5).
FreeBSD 15.1-STABLE-HBSD May 23, 2026 MRSAS(4)