Iowait Monitoring - Cisco MCS-7825-H3-IPC1 Service Manual

Chapter 3 Managing and Monitoring the Health of Cisco Unified Communications Manager Systems
When a service crashes, the corresponding trace files may have been overwritten. Cisco TAC needs the
trace files to troubleshoot the crash. In the case of CoreDumpFileFound, CodeYellow, and
CriticalServiceDown, the Enable Trace Download option should be enabled to assist Cisco TAC.

% IOwait Monitoring

High %IOwait indicates high disk input/output (I/O) activities. Consider the following high IOwait
conditions:
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You can use RTMT to identify processes that are responsible for high %IOwait:
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Figure 3-4
Uninterruptible Disk Sleep state. The FTP process is in the Uninterruptible Disk Sleep state.
Figure 3-4
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Heavy memory swapping—Check %CPU Time for Swap Partition to see if there is high level of
memory swapping activity. One potential cause of high memory swapping is memory leak.
DB activity—Database accesses Active Partition. If %CPU Time for Active Partition is high, then
most likely there are a lot of DB activities.
Common (or Log) Partition in the trace and log files storage location—Check the following:
Trace Log Center to see if there is any trace collection activity going on. If call processing is
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impacted (ie, CodeYellow), then consider adjusting trace collection schedule. If zip option is
used, please turning it off.
Trace setting at the detailed level because Cisco Unified CM generates a lot of trace. If high
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%iowait and/or Cisco Unified CM is in CodeYellow state, and Cisco Unified CM service trace
setting is at Detailed, please chance trace setting to "Error" to reduce the trace writing.
If %IOwait is high enough to cause CPUPegging alert, check the alert message to check processes
waiting for disk IO.
Go to RTMT Process page, sort by Status. Check for processes in Uninterruptible Disk Sleep state
Download RIS Data Collector PerfMonLog file to examine the process status for longer period of
time.
shows an example of RTMT Process window sorted by Status. Check for processes in
FTP Process in Uninterruptible Disk Sleep State
RTMT Monitoring of Cisco Unified CM System Health
Cisco Unified Communications Manager Managed Services Guide
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