CompTIA Linux+ (XK0-006)TroubleshootingMedium
An administrator runs `iostat -x 2` and observes the following for /dev/sda: r/s: 120 w/s: 340 await: 85.00 %util: 98.50 What does the %util value indicate about this disk?
- AThe disk is nearly saturated and is the likely I/O bottleneck
- BThe disk controller firmware is outdated and needs a driver update
- CThe value indicates CPU utilization, not disk activity
- D98.50% represents free disk space remaining
Show answer & explanationAnswer & explanation
Correct answer: A. The disk is nearly saturated and is the likely I/O bottleneck
%util in iostat -x shows the percentage of time the device was busy servicing I/O requests. A value near 100% combined with high await time (85ms) confirms the disk is saturated and is the bottleneck for the system's performance.
Why the other options are wrong
- B. %util has nothing to do with firmware versions.
- C. iostat -x reports disk statistics, not CPU utilization.
- D. %util measures busy time, not free space.
iostat %util
%util in iostat -x shows the percentage of time a block device was busy processing I/O requests; values near 100% indicate saturation.
- High %util + high await = disk bottleneck
- await measures average I/O request wait time in ms
- iostat -x <interval> gives extended per-device stats
Memory trick: %util near 100 = the disk has no idle time left, like a maxed-out cashier