Hardware RAID controllers present a single virtual drive to the operating system, which hides the raw SMART data of the individual physical disks. To bypass this, you must explicitly tell smartctl which physical disk on the controller you want to query using the -d megaraid,N flag. Step 1: Identify the Physical Device IDs
Implementation notes
To bypass the virtual layer, you must tell smartctl which specific physical disk you want to inspect by providing its (represented as 1. Find the Physical Device ID (
Fixing "smartctl open device /dev/sda failed: DELL or MegaRaid controller" Hardware RAID controllers present a single virtual drive
The smartctl open device failed error is a standard and expected response when querying a hardware RAID controller. It is not an error with the drives, but a notification that you are not using the proper syntax to access the physical devices behind the controller.
Even when using the correct megaraid,N syntax, you may still encounter issues:
Where:
List all physical disks in the RAID volume:
If this input was intended to be a search query or a ticket description, here is how it should be rewritten for clarity:
smartctl -a -d megaraid,E,S /dev/sda # Example: Enclosure 252, Slot 0 smartctl -a -d megaraid,252,0 /dev/sda Use code with caution. How to Find Your Physical Drive Slot IDs (N) Find the Physical Device ID ( Fixing "smartctl
megacli -ldinfo -lall
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
Because standard S.M.A.R.T. commands cannot pass straight through the RAID abstraction layer, smartctl fails unless you explicitly tell it how to bypass the controller and target a specific physical drive slot. How to Find Your Physical Drive Slot IDs
Hardware RAID controllers (like Dell PERC H330, H730, H740, or LSI MegaRAID 9260, 9361) create (logical drives). To the operating system, these volumes look like single block devices— /dev/sda , /dev/sdb , etc. But smartctl tries to send S.M.A.R.T. commands directly to that device file. The RAID controller intercepts those commands and does not pass them to individual physical drives unless explicitly instructed.