When disks are connected through such a controller, the Linux kernel does not see the individual physical drives. Instead, it only sees the , the RAID volume presented as /dev/sda , /dev/sdb , etc. When you run smartctl -i /dev/sda , the command is essentially trying to query that virtual drive, which doesn't have a SMART interface to report, triggering the error:
The RAID controller does not expose the physical disks through the standard SCSI layer. This is common with entry‑level RAID cards or those operating in a “simple” RAID mode.
: Run sudo smartctl --scan to see a list of detected physical drives and their specific megaraid identifiers.
To effectively manage your drives behind a Dell PERC or MegaRAID controller, keep these best practices in mind: When disks are connected through such a controller,
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.
Older versions of smartmontools do not support the Dell PERC/MegaRAID ioctl commands. Ensure you are running smartmontools version 6.0 or higher.
The operating system detects a singular storage repository mapped to a standard block node like /dev/sda . S.M.A.R.T. commands issued directly to /dev/sda attempt to read health metrics from this virtual container rather than the underlying hardware, triggering an instant generic terminal failure. This is common with entry‑level RAID cards or
Or:
To bypass this and query the physical disks directly, you must use the -d megaraid,N option. This flag uses the MegaRAID , a specific interface in the Linux kernel that allows tools like smartctl to send commands directly to the physical drives behind the RAID controller.
Assuming you want to monitor a disk with a PD number of 2, the smartctl command would be: To the operating system, these volumes look like
For example:
# Try N=0, then N=1, etc. smartctl -i -d megaraid,0 /dev/sda smartctl -i -d megaraid,1 /dev/sda