megaraid_sas_pdoff Driver

Many hard drives do not support hot-plugging, making them sensitive to sudden power loss if they are not properly shut down. The MegaRAID SAS RAID controller is primarily designed for servers, where hard drives may be connected to dual RAID controllers or housed in external disk enclosures.

This driver ensures a proper shutdown by sending the SCSI disk spin-down command {0x1b, 0x01, 0x00, 0x00, 0x00, 0x00} to all connected disks during the system shutdown process. This helps protect standard workstation hard drives from abrupt power loss when using a RAID controller.

How to Compile

For RHEL-based systems, install the necessary dependencies with:

dnf install gcc kernel-devel-$(uname -r)

Then, navigate to the source directory:

cd 07.731.01.00-3
./compile.sh

This will generate the .ko kernel module file.

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Loading the Driver manually

Assuming the compiled driver file is named megaraid_sas_pdoff.ko, load it with the following commands:

modprobe -r megaraid_sas
insmod megaraid_sas_pdoff.ko
lspci -v -s 07:00.0

Here, 07:00.0 is the PCI device number on this machine. Use lspci | grep SAS to find the correct PCI ID for your system.

Note: On some operating systems, the megaraid_sas driver cannot be unloaded using modprobe. In such cases, you may need to use driverctl to manually override the driver.

insmod megaraid_sas_pdoff.ko
driverctl set-override 0000:07:00.0 megaraid_sas_pdoff
lspci -v -s 07:00.0

Install to OS Set perferred at OS startup

The full step is

1. cd into the source directory, here is '07.731.01.00-3'.
2. build the kernel module.
3. run 'install_to_kernel.sh' to install.
4. using driverctl to set driver override.

cd 07.731.01.00-3
./compile.sh
./install_to_kernel.sh
driverctl set-override 0000:07:00.0 megaraid_sas_pdoff

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Modifying the Driver

For customization, refer to the last section of megasas分析笔记.
Copy the relevant function into the source code and call it inside and at the end of megasas_shutdown().