LSI MegaRAID Driver Download and Installation Guide

You can install the LSI MegaRAID driver by downloading the correct package from Broadcom’s support site (which now owns the LSI storage business), or by letting Windows detect it automatically through Device Manager once the card is seated. Below is the full process, including what to do when the automatic route does not work.

LSI MegaRAID cards have been a staple in workstations and small servers for a long time, and a lot of them are still running today, sometimes decades after the model was first released. Since LSI was bought by Avago and later folded into Broadcom, the trickiest part of this whole process is usually just finding where the current driver actually lives, not installing it. I have re-driver several older MegaRAID SAS cards for clients migrating old file servers to Windows 11, and the steps below reflect what has consistently worked.

Applies To	LSI MegaRAID SAS controllers (9260, 9271, 9361, 9440 series and similar)
Author/Publisher	Broadcom Inc. (formerly LSI Corporation / Avago Technologies)
Driver/Software Date	Model-dependent, check Broadcom’s storage adapter support page for the current build
Version	Varies by controller generation and MegaRAID firmware
File Name	megasas2.sys / megasr.sys
File Size	Approximately 3-12 MB depending on package
OS Compatibility	Windows 10, Windows 11, Windows Server (64-bit)

Finding and Installing the Driver

1. Open Device Manager and check under Storage controllers for the exact card name, or look at the physical label on the card if the system will not boot into Windows.
2. Go to the Broadcom support download search and enter your MegaRAID model number.
3. Download the Windows driver package matching your OS version (Windows 10 vs Windows 11 downloads are usually listed separately).
4. Run the installer as Administrator, or extract it if it is a driver-only ZIP file.
5. Reboot the system once installation completes.

Manual Installation via Device Manager

If you only have a folder of driver files rather than a full installer, or the setup wizard errors out, install manually:

• Extract the driver package to a local folder.
• Open Device Manager, find the MegaRAID controller (it may appear as “RAID Controller” or under Other devices if undetected).
• Right-click, select Update driver, then Browse my computer for drivers.
• Point it to the extracted folder and let Windows install the matching .inf file.
• Restart when prompted; the array typically will not mount properly until after this reboot.

Windows 10 and Windows 11 Behavior

Windows 10 generally accepts older LSI driver packages without much fuss, even ones signed years ago. Windows 11 is stricter about driver signing, and some legacy MegaRAID drivers built for Windows 7 or Server 2008 era systems will simply refuse to install unattended. If you hit that wall, check whether Broadcom has released a newer signed package for your card family before trying workarounds like disabling driver signature enforcement, which is not something you want on a production server long-term.

Per Wei Ling Tan, who is an IT infrastructure lead at a logistics company, “Our warehouse management server still uses an LSI MegaRAID 9271 card, and the only time we had trouble was during a Windows 11 migration where the old driver was flagged as unsigned. Grabbing the current package straight from Broadcom instead of our old install media solved it in minutes.”

Checking the Array After Installation

Once the driver is installed and the system has rebooted, confirm everything is healthy before relying on it:

1. Open Device Manager and verify no warning icons appear on the storage controller entry.
2. Check Disk Management to confirm the RAID volume shows as a single disk with the expected capacity.
3. If you installed MegaRAID Storage Manager, open it and check array status and disk health.
4. Run a quick read/write test by copying a large file to the array to confirm performance looks normal.

For general background on how hardware RAID controllers present arrays to Windows, How-To Geek has approachable explainers that are useful if you are newer to RAID concepts.

Frequently Asked Questions

Is LSI still a company, or is this driver from Broadcom now?

LSI Corporation was acquired by Avago Technologies, which later renamed itself Broadcom. All current MegaRAID driver downloads are hosted on Broadcom’s support site, though the card and utility branding still often says LSI or MegaRAID.

What is the difference between megasas2.sys and megasr.sys?

megasas2.sys is the full hardware RAID driver for true MegaRAID SAS controllers. megasr.sys is used for the software RAID (SRCS) mode found on some motherboard-integrated LSI chips, which behaves differently and has fewer features.

My MegaRAID card is not listed on Broadcom’s current site. What now?

Older discontinued models sometimes get moved to a legacy or archive support section rather than removed outright. Search Broadcom’s site by the exact model number, and if it truly is not there, community archives on hardware forums are often the next best source.

Do I need MegaRAID Storage Manager for the array to work?

No, the driver alone lets Windows use the array. Storage Manager is a monitoring and management utility that is helpful but not required for basic operation.

Can I mix drive sizes in a MegaRAID array?

Technically yes, but the array will treat every drive as the size of the smallest one in most RAID levels, which wastes capacity on larger drives. It is best to use matched drives when possible.

Conclusion

Installing the LSI MegaRAID driver mostly comes down to finding the right download on Broadcom’s site now that the LSI brand has changed hands, and matching the exact controller model rather than a generic MegaRAID label. Follow the steps above, verify the array in Device Manager and Disk Management afterward, and your server should be back to full speed.