Do you know the exact or MegaRAID controller model ? Are you using SATA or SAS drives? Share public link
Enterprise storage controllers, such as the series (H710, H730, H740p, etc.), isolate physical storage drives from the operating system kernel.
If you are managing Dell PowerEdge servers, you have likely encountered the frustrating smartctl open device /dev/sda failed: Dell or MegaRAID controller, please try adding '-d megaraid,N' . This error occurs because smartctl tries to access the hard drive directly, but the Dell PERC (PowerEdge RAID Controller), which is based on LSI MegaRAID technology, masks the physical drives behind a logical RAID abstraction layer.
smartctl -a -d megaraid,N /dev/sdX
The smartctl open device failed: DELL or MegaRaid controller error is a gateway, not a barrier. Understanding the "why" behind it is the first step to mastering hardware RAID monitoring. With the -d megaraid,N flag, you unlock the ability to keep a granular, proactive eye on the health of every physical disk in your array. Do you know the exact or MegaRAID controller model
(Note: Replace storcli with perccli on older or proprietary Dell installations).
The command reaches the virtual device exposed to the operating system.
EID:Slt DID State DG Size Intf Med 252:0 7 Onln 0 465.25 GB SATA HDD 252:1 6 Onln 1 465.25 GB SATA HDD 252:2 5 Onln 2 74.0 GB SATA SSD 252:3 4 Onln 2 74.0 GB SATA SSD
True SAS enterprise drives utilize a slightly different command topology. While -d megaraid,N typically auto-detects the transport protocol, you may occasionally need to enforce SCSI translation explicitly if the output looks corrupted: smartctl -a -d scsi /dev/sda Use code with caution. If you are managing Dell PowerEdge servers, you
Open the configuration file (usually located at /etc/smartmontools/smartd.conf or /etc/smartd.conf ): nano /etc/smartmontools/smartd.conf Use code with caution. Comment out any default scanning lines like DEVICESCAN .
What (Ubuntu, RHEL, Proxmox, etc.) is the server running?
Smartctl open device: /dev/sda failed: DELL or MegaRaid controller, please try adding '-d megaraid,N'
This error occurs when the RAID controller’s firmware does not fully understand the S.M.A.R.T. response from the disk. It is most frequently seen with consumer SATA SSDs (e.g., Samsung 870 EVO) attached to older PERC controllers like the H730 Mini. The controller can identify the disk and confirm that SMART is enabled, but it cannot translate the actual S.M.A.R.T. data payload. Understanding the "why" behind it is the first
/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
The solution involves adding the -d megaraid,N option to the smartctl command. Here's how:
For example, to check the very first physical disk on the controller, try running: smartctl -a -d megaraid,0 /dev/sda Use code with caution.