Chapter 1
System Management
Course: Comptia Linux Xk0 006
Subject: Comptia Linux Xk0 006
Chapter: Troubleshooting
Storage issues in Linux can manifest in various forms such as performance degradation, unresponsiveness, or data corruption. Effective troubleshooting involves examining latency, throughput, IOPS, and underlying device or configuration problems using tools like iostat, iotop, vmstat, smartctl, and dmesg.
1. High latency
High latency refers to delays in completing read or write operations on a storage device. It often leads to sluggish system performance, especially under I/O-heavy workloads like databases, file servers, or backup systems.
Symptoms:
- Slow file reads or writes
- Applications becoming unresponsive
- Noticeable delays in data retrieval
- High await value when using tools like iostat
Diagnosis:
bash
iostat -xz 1
Focus on these columns:
- await: Total average time per I/O request
- svctm: Time spent servicing requests by the device
If await is significantly greater than svctm, it means I/O requests are spending a long time waiting in the queue before they are handled by the disk, which indicates latency issues.