To fix this error, you need to tell smartctl to use the megaraid driver and specify which physical disk to query using its N number.
N is the physical disk number (or “drive ID”) as reported by the RAID controller, not the OS device name. It typically ranges from 0 to the number of physical drives minus one.
Example: If your RAID array has 4 physical disks, N could be 0, 1, 2, 3.
If you know disk sizes differ, you can try:
smartctl -i -d megaraid,0 /dev/sda
smartctl -i -d megaraid,1 /dev/sda
One will fail (non-existent drive) or return info for the correct disk.
If you want, I can produce:
The error message "smartctl open device /dev/sda failed: DELL or MegaRaid controller, please try adding '-d megaraid,N'"
occurs because hardware RAID controllers (like Dell PERC or LSI MegaRAID) hide individual physical drives from the operating system, presenting only a "virtual" drive instead. To view the SMART health of a specific physical disk, you must bypass the RAID abstraction using a specialized "cheat code" syntax. Unix & Linux Stack Exchange 1. Identify the Correct Device ID ( " in the command represents the Physical Drive ID
on the controller, not the OS drive letter. You can find these IDs using one of the following methods: Thomas-Krenn.AG Fastest Method smartctl --scan
to see a list of detected devices and their corresponding MegaRAID IDs. Detailed Method (using Dell PERCCLI perccli /c0 /eall /sall show . Look for the (Device ID) column in the output table. Alternate (MegaCLI) MegaCli -PDList -aALL | grep "Device Id" Server Fault 2. Run the Correct Command Once you have the ID (e.g., if the drive ID is ), use the following syntax: For SAS/SCSI Drives smartctl -a -d megaraid,0 /dev/sda For SATA Drives If the standard command fails, try adding the smartctl -a -d sat+megaraid,0 /dev/sda Unix & Linux Stack Exchange Troubleshooting Common Issues
The error message "smartctl open device: /dev/sda failed: DELL or MegaRAID controller, please try adding '-d megaraid,N'" occurs because smartctl is trying to talk directly to a virtual RAID volume (e.g., /dev/sda) instead of the physical hard drives hidden behind the controller.
To fix this, you must use the -d megaraid,N flag to "pass through" the RAID controller and address a specific physical disk ID (N). 1. Identify the Correct Device ID (N) The number
corresponds to the Device ID assigned by your RAID controller, which may not simply be 0, 1, 2, etc.. Use one of the following methods to find it: To fix this error, you need to tell
Via smartctl scan: Run sudo smartctl --scan to see a list of detected physical drives and their specific megaraid identifiers.
Via MegaCli/StorCLI: If you have RAID management tools installed, run:
sudo storcli /c0 /eall /sall show (Look for the DID or Device ID column). sudo MegaCli -PDList -aALL | grep "Device Id". 2. Run the Correct smartctl Command
Once you have the ID (e.g., if the ID is 12), use it in your command:
For SAS/SCSI drives:sudo smartctl -a -d megaraid,12 /dev/sda
For SATA drives: Some controllers require a combined flag:sudo smartctl -a -d sat+megaraid,12 /dev/sda Troubleshooting Common Issues Smartmontools with MegaRAID Controller - Thomas-Krenn.AG
It sounds like you’re encountering the classic smartctl error when trying to access a physical disk behind a Dell PERC (MegaRAID) controller. The message you're referencing is essentially telling you to use the correct device syntax: -d megaraid,N.
Here’s a breakdown of good content you can use—whether for a knowledge base article, a forum post, or internal documentation.
Subject: Fixing smartctl "open device dev/sda failed" on Dell/MegaRAID
Content:
To fix the error smartctl open device /dev/sda failed, you must specify the RAID controller interface and logical drive number.
Use this syntax:
smartctl -a -d megaraid,<Enclosure_Device> /dev/sdX
Example for a Dell PERC controller:
smartctl -a -d megaraid,0 /dev/sda
💡 Pro tip: Use
-d megaraid,NwhereNis the physical disk index behind the controller (0,1,2...). Runsmartctl --scanto find available devices.
List all physical disks in the RAID volume:
smartctl --scan -d megaraid
or
megacli -PDList -a0 | grep "Slot Number" # (if MegaCLI installed)
The error is not a bug – it's a deliberate safety mechanism. The RAID controller hides physical disks by design. Using -d megaraid,N is the correct, supported, and safe method to query SMART data on Dell PERC and LSI MegaRAID controllers. Ignoring this flag risks querying the wrong device or corrupting the RAID metadata.
Always use:
smartctl -a -d megaraid,<physical_disk_id> /dev/sda
This error occurs because the operating system sees your RAID controller (e.g., a LSI MegaRAID
) as a single logical device, effectively hiding the physical health data of the individual drives behind it
cannot "see through" the controller by default, it fails to open The Fix: Using the -d megaraid,N To access a specific physical drive, you must tell which "slot" or it occupies on the controller. Identify the Device ID ( Use a RAID management tool like
to find the physical drive IDs. For many Dell servers, the first drive is often ID Run the corrected command: with your drive's ID and run the command with sudo smartctl -a -d megaraid,N /dev/sda Use code with caution. Copied to clipboard Example for the first drive: sudo smartctl -a -d megaraid,0 /dev/sda For SATA drives behind the controller: You may need sat+megaraid,N www.couyon.net Why this happens
Fix: smartctl "Open Device Failed" on Dell or MegaRAID Controllers
When running smartctl on a Dell PowerEdge server or any system using a MegaRAID (LSI/Broadcom) controller, you often encounter this error:Smartctl open device: /dev/sda failed: Dell or MegaRAID controller, please try adding '-d megaraid,N'.
This happens because the operating system sees a virtual logical drive (the RAID array), but smartctl needs to talk directly to the physical disks hidden behind the controller. The Solution: Using the -d megaraid,N Flag One will fail (non-existent drive) or return info
To bypass the virtual layer, you must tell smartctl which specific physical disk you want to inspect by providing its Device ID (represented as 1. Find the Physical Device ID (
You cannot guess this number, as it doesn't always start at 0. Use the storcli (or older MegaCli) utility to find the DID (Device ID). Command: sudo storcli /c0 /eall /sall show
What to look for: Locate the DID column in the "Drive Information" table. If your disk is in slot 1 and has a DID of 11, then 2. Run the Correct smartctl Command
Once you have the ID, run the command against the controller's device node (usually /dev/sda or /dev/bus/0). Cannot get smartctl working - Unix & Linux Stack Exchange
The error "smartctl open device: /dev/sda failed: DELL or MegaRaid controller" occurs because standard smartctl commands cannot "see" through a Dell PERC or MegaRAID controller to the individual physical disks. To fix this, you must specify the raid type and the physical disk's ID using the -d megaraid,N flag. How to Fix the Error To successfully query your drive, follow these steps:
Identify Disk IDs:You need to find the correct value for N (the Device ID). You can automatically list all detectable physical drives and their IDs by running: smartctl --scan
Alternatively, use the Dell PERC/MegaRAID utility to list physical drives:MegaCli -PDList -aALL | grep "Device Id"
Run the Correct Command:Once you have the ID (e.g., 0), run smartctl with the specific device type: smartctl -a -d megaraid,0 /dev/sda
Note: On some systems, you may need to use /dev/bus/0 instead of /dev/sda to ensure stability. Recommended Monitoring Configuration
If you want the Smartmontools daemon (smartd) to monitor these drives automatically, update your /etc/smartd.conf file:
Standard SAS/SATA setup:/dev/sda -d megaraid,0 -a/dev/sda -d megaraid,1 -a Troubleshooting Persistent Failures If you still see failures after adding the -d flag: Error with smartctl on Dell/Megaraid · Issue #660 - GitHub