Smartctl Open Device Dev Sda Failed Dell Or Megaraid Controller Please Try Adding 39d Megaraid N 39 Extra Quality [updated] Jun 2026

"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.

Resolving "smartctl open device dev/sda failed" on Dell & MegaRAID Controllers: A Complete Guide to the -d megaraid,N Parameter Introduction If you manage servers with hardware RAID controllers—especially Dell PowerEdge servers with PERC (PowerEdge RAID Controller) or any system using a Broadcom (formerly LSI) MegaRAID controller—you have likely encountered a frustrating error when trying to check disk health with smartctl : smartctl open device: /dev/sda failed: DELL or MegaRAID controller, please try adding -d megaraid,N

This message appears because smartctl (part of the smartmontools package) expects to communicate directly with a physical disk. However, a RAID controller presents a virtual drive (e.g., /dev/sda , /dev/sdb ) to the operating system. The OS sees only the logical array, not the individual physical disks behind the controller. To get S.M.A.R.T. data from each physical drive, you must bypass this virtualization using the -d megaraid,N flag. In this article, we will explain:

Why this error occurs How to correctly use the -d megaraid,N option How to identify physical disk numbers ( N ) How to monitor all drives in a RAID array Script examples for automation Common pitfalls and solutions "smartctl open device dev sda failed dell or

Understanding the Error What is smartctl ? smartctl is a command-line tool used to control and query S.M.A.R.T. (Self-Monitoring, Analysis, and Reporting Technology) data from hard drives and SSDs. It helps predict drive failures by reporting attributes like Reallocated Sectors, Reported Uncorrectable Errors, Temperature, and more. Why does the error appear? Hardware RAID controllers (like Dell PERC H330, H730, H740, or LSI MegaRAID 9260, 9361) create RAID volumes (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. Thus, the error message is actually helpful : it tells you exactly what to do—add the -d megaraid,N option.

The Solution: -d megaraid,N Syntax smartctl -a -d megaraid,N /dev/sda

-a : Display all S.M.A.R.T. information (or use -i for identity, -H for health, -A for attributes) -d megaraid,N : Disk type and physical drive number /dev/sda : The logical device corresponding to the RAID array containing that physical disk The OS sees only the logical array, not

What is N ? N is the physical disk number (or “drive ID”) as reported by the RAID controller , not the OS device name. It typically ranges from 0 to the number of physical drives minus one. Example: If your RAID array has 4 physical disks, N could be 0 , 1 , 2 , 3 . First step: find physical disk numbers Before using smartctl , you need to map logical drives to physical disk IDs. Method 1: megacli (Broadcom/LSI) or storcli 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. Method 2: smartctl --scan Sometimes helpful for direct-attached drives, but less so behind RAID. Try: smartctl --scan In this article, we will explain: Why this

It may show /dev/sda -d megaraid,0 if previously detected, but not guaranteed. Method 3: Inference by size or model (less reliable) If you know disk sizes differ, you can try: smartctl -i -d megaraid,0 /dev/sda smartctl -i -d megaraid,1 /dev/sda

One will fail (non-existent drive) or return info for the correct disk.