Before using smartctl, you need to map logical drives to physical disk IDs.
If your controller presents multiple logical drives (/dev/sda, /dev/sdb, /dev/sdc), then /dev/sda may contain physical disks with IDs 0,1,2 and /dev/sdb may contain physical disks with IDs 3,4,5. The N value is controller-wide, not per logical drive. So you can usually access all physical disks through any logical device, but safest is to use the logical drive that belongs to the same RAID group. When in doubt, try all N on /dev/sda.
Better: use storcli to see which PD belongs to which DG (drive group / logical drive).
For MegaRAID/Dell PERC, the most reliable tool is storcli (successor to megacli):
storcli /c0 /eall /sall show
That lists all physical disks in controller 0. Look for DID (Device ID) or ID – that is your N.
Example output snippet:
PD LIST :
=======
EID:Slt DID State DG Size Intf Med
16:0 0 Onln 0 1.818 TB SATA HDD
16:1 1 Onln 0 1.818 TB SATA HDD
Here, DID column gives 0 and 1 as physical drive numbers.
NVMe drives behind a Dell PERC 11 or 12 (e.g., H755) are often passed through as NVMe namespaces, but if they are RAIDed, you may need -d nvme-megaraid,N on newer smartmontools (version 7.3+).
smartctl -a -d megaraid,2 /dev/sda
Extra quality check: To verify correct syntax before running, do:
smartctl -d megaraid,0 /dev/sda --scan-open
"smartctl open device dev sda failed dell or megaraid controller please try adding -d megaraid,N"
The article explains the error, why it happens, how to fix it, and includes best practices for monitoring RAID drives behind Dell PERC / MegaRAID controllers.
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): Before using smartctl , you need to map
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
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:
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
When you see the error Smartctl open device: /dev/sda failed: DELL or MegaRaid controller, it means smartctl cannot directly access the physical drive because it is "hidden" behind a RAID controller. To fix this, you must specify the exact physical drive ID using the -d megaraid,N flag. 1. Find the Correct Physical Drive ID (
is the physical device ID on the RAID controller. You can find it using one of the following tools: For MegaRAID/Dell PERC, the most reliable tool is
Using smartctl: Run sudo smartctl --scan to see a list of detected devices and their corresponding IDs.
Using StorCLI: Use the command sudo storcli /c0 /eall /sall show and look for the DID (Device ID) column.
Using MegaCli: Run sudo MegaCli -pdlist -a0 | grep 'Device Id' to list the IDs of all physical drives on the first controller. 2. Run the Correct smartctl Command Once you have the ID (e.g., 8), use it in your command: General Syntax:sudo smartctl -a -d megaraid,N /dev/sda
Example for Drive ID 8:sudo smartctl -a -d megaraid,8 /dev/sda
For SATA Drives: If the drive is SATA rather than SAS, you may need a combined flag:sudo smartctl -a -d sat+megaraid,N /dev/sda Summary of Flags -a: Displays all SMART information.
-d megaraid,N: Tells smartctl to talk to the RAID controller to reach physical disk
/dev/sda: The logical device name (though behind a RAID, this often acts as the entry point to the controller). Error with smartctl on Dell/Megaraid · Issue #660 - GitHub
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 That lists all physical disks in controller 0
Error: Smartctl Open Device Failed
When attempting to run smartctl, a popular command-line utility for monitoring and managing disk drives, on a Linux system, you might encounter an error message similar to:
smartctl open device /dev/sda failed: Dell or MegaRAID controller. Please try adding '-d megaraid,N'
This error typically occurs when smartctl is unable to directly access the disk drive /dev/sda due to the presence of a RAID controller, specifically a Dell or MegaRAID controller.
Understanding the Issue
The error message suggests that the disk drive is behind a RAID controller, which is a hardware component that manages multiple disk drives as a single logical unit. In this case, the controller is a Dell or MegaRAID device. The smartctl utility needs to communicate with the disk drive through this controller, but it doesn't know how to do so by default.
Solution: Specifying the RAID Controller
To resolve this issue, you need to inform smartctl about the presence of the MegaRAID controller and the logical drive number (N) associated with the disk drive you want to monitor. You can do this by adding the -d megaraid,N option to the smartctl command.
Here's an example:
smartctl -d megaraid,0 /dev/sda
In this example, 0 is the logical drive number (N) associated with the disk drive /dev/sda. You may need to adjust this value depending on your specific configuration.
Finding the Logical Drive Number
To find the logical drive number, you can use the megacli command, which is a utility provided by LSI (now part of Broadcom) for managing MegaRAID controllers.
Here's an example:
megacli -ldinfo -lall
This command will display information about all logical drives configured on the MegaRAID controller. Look for the logical drive number associated with the disk drive you want to monitor.
Additional Tips
By following these steps and adding the -d megaraid,N option to the smartctl command, you should be able to successfully monitor and manage your disk drives behind a Dell or MegaRAID controller.