Performance Analysis for Oracle (PAO) is reporting very high Disk Utilization (way above the upper baseline), while the other metric values (reads, writes, CPU...) are all within the baseline.
OS Disk Utilization metric is not supported on Linux platforms
At the instance level, the metric OS Disk Utilization is not supported on Linux platforms. This metric is also seen in the Performance Analysis Home Page under the name Disk (% Busy). We have an open CR for this issue, CR0217996, also related CR0217995 (OS system logical reads and writes not supported on Linux).
These are to be fixed in a future version. These were in the 6.3 release notes, but for some reason did not make it into the 6.5 release notes. However, this isssue has not been resolved in PAO 6.5.