4.1.2. Troubleshooting Storage (Drives and RAID)

💡 First Principle: To diagnose storage failures, you must interpret OS errors (e.g., "Bootable device not found"), listen for physical cues (clicking), and check status indicators (S.M.A.R.T., RAID controller) to determine if the issue is logical or physical.

Scenario: A user reports their computer is extremely slow to boot and open files. You hear a faint, repetitive clicking sound coming from the case. You immediately form the theory that the mechanical hard drive is physically failing.

Technician's Diagnostic Path:

1. Primary Action: Inform the user to stop using the computer to prevent further damage. Your immediate priority is data preservation, not repair.
2. Plan for Data Recovery:
   • Action: Connect the failing drive to a different computer as a secondary drive (e.g., via a USB-to-SATA adapter).
   • Action: Attempt to copy the user's critical data to a new, healthy drive.
3. Plan for Repair:
   • Action: Replace the failing HDD with a new SSD for a significant performance improvement.
   • Action: Perform a clean installation of the operating system on the new SSD and restore the user's backed-up data.

⚠️ Common Pitfall: Attempting to "fix" a physically failing hard drive with software tools. If a drive is making physical noises, the priority is to back up the data before it fails completely, not to run disk checkers.

Key Trade-Offs:

• Data Recovery Software vs. Professional Service: For critical data on a failed drive, professional data recovery services have specialized tools and clean rooms but are very expensive. Software tools are a last resort and can sometimes make the problem worse.

Reflection Question: In a RAID 5 array, one drive fails. What is the status of the array, what is the immediate risk, and what is the first step you should take?