A systems administrator is investigating reports of intermittent, slow I/O performance on a Linux server's primary data volume. The volume is hosted on a hardware RAID 5 array. The server's performance monitoring tools show high disk latency (%iowait) but no corresponding CPU or memory pressure. No configuration changes have been made recently. Which of the following actions is the most effective next step to diagnose the root cause of the storage problem?
Use a disk performance benchmarking tool, such as fio or iostat, to measure the array's read/write speeds.
Schedule and run a filesystem check utility, such as fsck, on the affected volume.
Review system logs, such as dmesg or /var/log/syslog, for I/O errors or RAID controller messages.
Access the hardware RAID controller's management utility to verify the array's health status.
The correct answer is to review system logs. In a Linux environment, kernel-level messages, including I/O errors from storage devices and RAID controller status updates, are sent to the kernel ring buffer and typically logged to files like /var/log/syslog or are viewable with commands such as dmesg and journalctl. These logs are the most direct source for identifying hardware issues like a degrading disk, which is a common cause of intermittent slowness and high I/O wait times in a RAID array.
Accessing the RAID controller's management utility is a valid and useful step, but system logs often capture the same hardware alerts as well as OS-level context, making them a more comprehensive initial diagnostic tool. Running a performance benchmark would only confirm the reported slowness, not diagnose its cause. Running a filesystem check (fsck) is used to fix filesystem corruption, which is less likely to cause intermittent performance issues than a failing drive, and it typically requires taking the volume offline, making it a disruptive and less appropriate initial step.