How to Diagnose Linux Server Issues in the First 60 Seconds with 10 Essential Commands

When a Linux server shows performance problems, the first minute is critical. Netflix's performance engineering team shares ten standard command‑line tools that reveal system health, resource saturation and errors.

1. uptime

uptime

The command shows the system load averages for the past 1, 5 and 15 minutes, indicating how many tasks are waiting to run.

2. dmesg | tail

dmesg | tail

Displays the latest kernel messages, useful for spotting OOM kills or network errors.

3. vmstat 1

vmstat 1

Shows virtual memory, CPU and I/O statistics every second; key fields include r (runnable tasks), free memory, si/so (swap activity) and us/sy/id/wa.

4. mpstat -P ALL 1

mpstat -P ALL 1

Prints per‑CPU utilization, helping to identify single‑threaded bottlenecks.

5. pidstat 1

pidstat 1

Reports CPU usage per process at regular intervals, allowing you to spot processes that consume many CPUs.

6. iostat -xz 1

iostat -xz 1

Provides detailed block‑device statistics such as r/s, w/s, await and %util to detect disk saturation.

7. free -m

free -m

Shows total, used and free memory, buffers and cache; the “-/+ buffers/cache” line gives a more accurate view of usable memory.

8. sar -n DEV 1

sar -n DEV 1

Monitors network interface throughput (rxkB/s, txkB/s) and interface utilization.

9. sar -n TCP,ETCP 1

sar -n TCP,ETCP 1

Summarizes TCP activity: active/passive connections, retransmissions and packet errors.

10. top

top

Combines many of the above metrics in a dynamic view; useful for a quick sanity check but may miss intermittent spikes.

By following the USE (Utilization, Saturation, Errors) methodology and checking these metrics in order, you can quickly narrow down the root cause of performance degradation.