The error message "Smartctl open device: /dev/sda failed: DELL or MegaRaid controller, please try adding '-d megaraid,N'" occurs because RAID controllers like the Dell PERC series hide physical hard drives behind a virtual abstraction layer. When you run a standard smartctl command on /dev/sda, the utility only sees the "Virtual Drive" created by the controller, which does not support direct S.M.A.R.T. queries. The Solution: Using the -d megaraid,N Flag
To bypass the virtual layer and talk directly to a specific physical disk, you must tell smartctl exactly which physical slot ( ) to target. Syntax: smartctl -a -d megaraid,N /dev/sda For SATA drives: Sometimes you must use sat+megaraid,N. The Value of
: This represents the Device ID (DID) or physical slot number on the controller. How to Find the Correct "N"
If you don't know which physical disk is which, use these methods:
Smartctl Scan: Run smartctl --scan to see if the utility can auto-detect the available physical drive numbers.
MegaCLI / StorCLI: These proprietary Dell/Broadcom tools provide the exact "Device ID" (DID) for each drive. Command: sudo storcli /c0 /eall /sall show. Look for the DID column; use these integers for
Trial and Error: In smaller setups, you can often find your drives by testing sequential numbers (e.g., 0, 1, 2...). Common Pitfalls Error with smartctl on Dell/Megaraid · Issue #660 - GitHub
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. The error message "Smartctl open device: /dev/sda failed:
(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
Here’s a bash one-liner to check all physical disks on the first controller:
for pd in 0..15; do smartctl -H -d megaraid,$pd /dev/sda &>/dev/null; if [ $? -eq 0 ]; then echo "PD $pd OK"; else echo "PD $pd missing or error"; fi; done
smartctl --scanSometimes helpful for direct-attached drives, but less so behind RAID. Try:
smartctl --scan
It may show /dev/sda -d megaraid,0 if previously detected, but not guaranteed. the generic -d megaraid
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
megaraid,0 → First virtual disk’s physical drive 0/dev/sda → The controller device node (not the raw disk)💡 Pro tip: Use
-d megaraid,NwhereNis the physical disk index behind the controller (0,1,2...). Runsmartctl --scanto find available devices.
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
When using on a Dell server equipped with a MegaRAID (PERC) controller, you may encounter the following error:
Smartctl open device: /dev/sda failed: DELL or MegaRaid controller, please try adding '-d megaraid,N'
This happens because the operating system only sees the "virtual" RAID volume (e.g.,
), while the physical disks are hidden behind the controller. To access a physical drive's SMART data, you must tell which specific physical disk index ( ) to query. Thomas-Krenn.AG How to Resolve the Error To successfully query your drives, follow these steps: Identify the Physical Disk Index ( You need the (DID) of the physical disk. Use one of the following tools:
/opt/MegaRAID/MegaCli/MegaCli64 -pdlist -aALL | grep 'Device Id' to see the IDs for all disks. storcli /c0 /eall /sall show and look for the Smartctl Scan : You can also try smartctl --scan
to see if the utility can automatically detect the correct mapping for you. Run the Correct Smartctl Command Once you have the index (for example, ), use the (device type) flag: For SAS/SCSI Drives smartctl -a -d megaraid,11 /dev/sda For SATA Drives sat+megaraid smartctl -a -d sat+megaraid,11 /dev/sda www.couyon.net Summary Table: Syntax by Drive Type Drive Type Syntax Command smartctl -a -d megaraid,N /dev/sda smartctl -a -d sat+megaraid,N /dev/sda Troubleshooting Tips Error with smartctl on Dell/Megaraid · Issue #660 - GitHub
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. N flag is the correct interface.
Here’s a breakdown of good content you can use—whether for a knowledge base article, a forum post, or internal documentation.
Dell’s PERC cards (especially Series 7, 8, 9, 10, and 11) are rebranded LSI MegaRAID controllers. Therefore, the generic -d megaraid,N flag is the correct interface.