CompTIA Linux+ XK0-006 (V8) Practice Question

The correct answer is smartctl -a /dev/sda. The dmesg output showing 'I/O error, dev sda' points to a hardware issue with the /dev/sda device. The smartctl utility is used to control and monitor the Self-Monitoring, Analysis, and Reporting Technology (SMART) system built into modern hard drives. Using the -a option displays all SMART information for the device, including health status, error logs, and attributes that can predict drive failure, such as Reallocated_Sector_Ct and Current_Pending_Sector. This is the most direct and appropriate first step to assess the physical health of the drive.

• fsck /dev/sda1 is incorrect because fsck is used to check and repair a filesystem on a partition (e.g., sda1), not the physical drive (sda). While I/O errors can lead to filesystem corruption, fsck addresses the filesystem's integrity, not the underlying cause of the physical device failure.
• badblocks -v /dev/sda is incorrect for this initial step. While badblocks can scan a device for bad sectors, it is a time-consuming and potentially destructive (in write mode) test. The smartctl command is a much faster, non-intrusive way to get the drive's own self-reported health status first.
• iostat -x /dev/sda is incorrect because iostat is a tool for monitoring I/O statistics, such as throughput and wait times. While it would likely show poor performance metrics for a failing drive, it does not provide the detailed diagnostic health report from the drive's SMART data needed to confirm a device failure.