Resolving smartctl "Open Device Failed" on Dell MegaRAID Controllers
If you encounter the error Smartctl open device: /dev/sda failed: DELL or MegaRaid controller, please try adding '-d megaraid,N', it means smartctl cannot directly talk to your hard drives because they are hidden behind a RAID controller (like a Dell PERC). To fix this, you must tell smartctl exactly which physical drive to look at using the -d megaraid,N flag. Why This Error Occurs
Standard Linux device names like /dev/sda often represent Virtual Disks (logical volumes) created by the RAID controller, not the physical hardware. Since SMART data exists on the physical disks themselves, smartctl needs to bypass the RAID abstraction layer. Step-by-Step Solution 1. Find the Physical Drive IDs
To use the correct N value, you first need to identify the Device ID (DID) assigned by the controller.
Option A: Using smartctl scanRun this command to see a list of physical drives the system can detect:smartctl --scanThis often returns lines like /dev/bus/0 -d megaraid,0.
Option B: Using MegaCLI or StorCLIIf you have Dell/LSI management tools installed, use them for more detail:storcli /c0 /eall /sall show (Look for the DID column).MegaCli -pdlist -a0 | grep "Device Id". 2. Run the Correct smartctl Command
Once you have the ID (e.g., 0, 1, or 32), use the -d (device type) flag: For SAS/SCSI Drives:smartctl -a -d megaraid,0 /dev/sda For SATA Drives:smartctl -a -d sat+megaraid,0 /dev/sda
Note: Replace 0 with your actual Device ID and /dev/sda with your controller's device node. Troubleshooting Common Issues Smartmontools with MegaRAID Controller - Thomas-Krenn.AG
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
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
This error occurs because Dell PERC and MegaRAID controllers hide physical drives behind a "Virtual Drive" abstraction. When you run smartctl /dev/sda, the tool tries to talk to the RAID volume itself, which doesn't support standard S.M.A.R.T. commands. Resolving smartctl "Open Device Failed" on Dell MegaRAID
To fix this, you must tell smartctl to bypass the abstraction and target a specific physical disk using the -d megaraid,N flag. 1. Find the Physical Drive IDs
The value for N (the Device ID) is not always 0, 1, 2, etc. You can find the correct IDs using two methods: Via smartctl scan: smartctl --scan Use code with caution. Copied to clipboard
This should return lines like /dev/bus/0 -d megaraid,4. In this case, 4 is your ID.
Via RAID utilities:If you have perccli (Dell) or storcli installed, run: /opt/MegaRAID/perccli/perccli64 /c0 /eall /sall show Use code with caution. Copied to clipboard Look for the DID (Device ID) or Slot Number column. 2. Run the Correct Command
Once you have the ID (let’s assume it’s 4), run the command against your logical device (e.g., /dev/sda): smartctl -a -d megaraid,4 /dev/sda Use code with caution. Copied to clipboard
Note for SATA Drives: If you are using SATA drives behind a MegaRAID controller, you might need to combine flags: smartctl -a -d sat+megaraid,4 /dev/sda Use code with caution. Copied to clipboard 3. Summary of Key Flags smartctl megaraid,N ( how to find the right value for N ? )
Many modern servers use hardware RAID controllers (e.g., Dell PERC / LSI MegaRAID) that present physical drives behind the controller, preventing smartctl from accessing raw device paths like /dev/sda. This feature outlines a robust implementation to detect such controllers, attempt appropriate access methods, and provide actionable fallback steps — including adding support for MegaRAID controllers (e.g., using the megaraid plugin/option) — to surface SMART data where possible.
If you are trying to run smartctl on a Dell server with a MegaRAID controller, you must tell the command which controller and which physical drive to query.
The correct syntax is:
smartctl -a /dev/sda -d megaraid,N
-a: Prints all SMART information./dev/sda: The device name (though often with Hardware RAID, you point to the generic device like /dev/sda or /dev/sg0 depending on the OS).-d megaraid,N: This tells smartctl to bypass the RAID controller logic.
N with the physical drive number (starting from 0).smartctl -a /dev/sda -d megaraid,0You cannot simply use /dev/sda. You must find the index number (N) of the physical drive behind the controller.
You can list all physical drives using the following command:
smartctl --scan
Output Example:
/dev/sda -d scsi # /dev/sda, SCSI device
/dev/bus/0 -d megaraid,0 # /dev/bus/0 [megaraid_disk_00], SCSI device
/dev/bus/0 -d megaraid,1 # /dev/bus/0 [megaraid_disk_01], SCSI device
In the example above, the physical drives are identified as megaraid,0 and megaraid,1. The number after the comma is the N value you need.
Alternatively, if you have the storcli utility installed, you can use storcli /c0 /eall /sall show to get a detailed list of drive slots and their IDs.
When attempting to run a simple smartctl -a /dev/sda (or smartctl -i /dev/sda) on a Dell PowerEdge server (or any system using an LSI MegaRAID or Dell PERC RAID controller), you often encounter this frustrating output:
smartctl open device: /dev/sda failed: DELL or MegaRAID controller? Please try adding '-d megaraid,N'
This error does not mean your hard drive is failing. It means smartctl cannot talk directly to the physical disk because the operating system only sees the virtual RAID volume (/dev/sda, /dev/sdb, etc.), not the individual physical drives. Summary Many modern servers use hardware RAID controllers
Check health of physical disk #2 behind controller:
smartctl -H -d megaraid,2 /dev/sda
Run a short self-test on physical disk #0:
smartctl -t short -d megaraid,0 /dev/sda
View full SMART attributes for disk #4:
smartctl -a -d megaraid,4 /dev/sda
Rating: ✅ Works perfectly once you add
-d megaraid,N.
Common mistake: Forgetting to specify the physical disk index.
Best practice: Use--scanto discover disks + indexes automatically.
This error occurs because your controller hides the physical drive's SMART data behind a RAID layer . To fix it, you must tell which specific physical disk ID to query. 🛠️ The Direct Fix Run the command using the -d megaraid,N flag, where is the drive's physical ID (starting from 0). Try this first (for the first drive): sudo smartctl -a -d megaraid,0 /dev/sda Use code with caution. Copied to clipboard 🔍 How to find the correct ID (N) megaraid,0
doesn't work, use one of these methods to find the actual physical drive IDs: sudo smartctl --scan
to see a list of detected drives and their corresponding IDs. Use MegaCLI / StorCLI (Dell Recommended):
If you have the RAID management tools installed, you can list all physical drives and their Device IDs sudo storcli /c0 /eall /sall show (Look at the "DID" column). sudo megacli -pdlist -a0 | grep "Device Id" Server Fault 💡 Common Variations
Depending on your drive type (SATA vs. SAS) and controller version, you might need a slightly different flag: For SATA drives behind MegaRAID: sudo smartctl -a -d sat+megaraid,0 /dev/sda Using the SCSI generic path: still fails, try the generic bus path: sudo smartctl -a -d megaraid,0 /dev/bus/0 If you are using a very old version of smartmontools , consider updating it
(version 7.0 or higher is recommended) as newer versions have significantly better support for Dell PERC and LSI MegaRAID controllers. Unix & Linux Stack Exchange If you'd like, let me know: server model (e.g., Dell PowerEdge R730) you're using. smartctl --scan If you're trying to monitor a
This error occurs because the LSI MegaRAID controller hides physical drives behind a virtual RAID volume . To access individual drive health data, you must tell which specific physical slot to query.
(device type) flag to specify the controller type and the physical drive index ( Command Syntax: sudo smartctl -a -d megaraid,N /dev/sda Use code with caution. Copied to clipboard : Displays all SMART information. -d megaraid,N : Points to the cap N raised to the t h power physical drive (starting at 0). : The logical device handle for the RAID controller. Step-by-Step Guide 1. Find the Physical Drive Index (
You need to identify which physical slot number corresponds to your drive. Use the MegaRAID management tool (like ) to list physical drives: # If using MegaCli sudo MegaCli -PDList -aALL | grep "Device Id" # If using perccli (common on newer Dell servers) sudo perccli /c0 /eall /sall show Use code with caution. Copied to clipboard Look for the "Device ID" "Slot Number" 2. Run the Smartctl Command Once you have the ID (e.g., sudo smartctl -x -d megaraid,0 /dev/sda Use code with caution. Copied to clipboard 3. Handling SATA Drives
If your drives are SATA (rather than SAS) behind a MegaRAID controller, you may need a combined device type: sudo smartctl -a -d sat+megaraid,N /dev/sda Use code with caution. Copied to clipboard Troubleshooting Tips Permissions : Always run these commands with or as root. Outdated Software megaraid,N still fails, ensure you are using a recent version of smartmontools Drive Handle
: Even if you have multiple physical drives, you usually use the same logical handle (e.g., ) for all of them; the part is what differentiates the physical disks. MegaCli commands to check for specific media or predictive failure errors? Check for Megaraid (and other Physical disk/raid) problems
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. -a : Prints all SMART information
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:
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
The error occurs because the Dell PERC or MegaRAID controller hides physical hard drives behind a virtual RAID volume. To bypass the controller and read the SMART data of a specific physical disk, you must use the -d megaraid,N parameter. Recommended Solutions
To fix the error and access your drive data, follow these steps: Identify the Physical Disk Number (N):
Run smartctl --scan to see a list of attached devices and their corresponding IDs.
Alternatively, use the Dell/LSI tool StorCLI with the command sudo storcli /c0 /eall /sall show and look for the DID (Device ID) column. Execute the Correct Command:
Replace N with the ID found in the previous step (e.g., 0, 1, 11, etc.). For SAS/SCSI drives: smartctl -a -d megaraid,N /dev/sda.
For SATA drives: Use the SAT passthrough syntax: smartctl -a -d sat+megaraid,N /dev/sda. Key Command Examples
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.
| Mistake | Why It Fails |
|---------|---------------|
| smartctl -a -d megaraid /dev/sda | Missing ,N – controller doesn’t know which physical disk. |
| smartctl -a -d megaraid,0 /dev/sg0 | Wrong device – use the block device /dev/sda, not the pass-through SG device. |
| smartctl -a -d sat+megaraid,0 /dev/sda | Overkill – sat is for USB bridges; not needed for direct SAS/SATA behind MegaRAID. |
| N too high | Controller returns error – try --scan to discover valid IDs. |