Issue Observed: High Memory utilization found at Juniper Routers.
We have found the memory utilization of routers have been increased to 65% during normal course of uses in network. This increase in memory utilization may or may not be normal and needs to be diagnosed.
Troubleshooting: We have checked the things at router, get RSI(request support Information Logs) and found all the system database and memory utilization normal. After doing more troubleshooting, even 95% memory utilization is normal.
We have found the memory utilization of routers have been increased to 65% during normal course of uses in network. This increase in memory utilization may or may not be normal and needs to be diagnosed.
Troubleshooting: We have checked the things at router, get RSI(request support Information Logs) and found all the system database and memory utilization normal. After doing more troubleshooting, even 95% memory utilization is normal.
Note: The memory utilization of 95 percent is not worrying, as
there is enough Inactive memory (1284M Inact); which can be made available by
the pageout daemon.”
Also find Explanation of Pageout Process - “When the system is under memory pressure,
the pageout process reuses memory from the free, cache, inact and, if
necessary, activepages.When thepageoutprocess runs, it scansmemory tosee
whichpages are good candidates to be unmapped and freedup. Thus, the
distinction between Active and Inactmemory is only usedby thepageout process to
determine which pool of pages to free first at thetime of a memory shortage”
Formula for Percentage Memory Utilisation is:
user@router> show system processes extensive
last pid: 6217; load averages: 0.00, 0.00, 0.00 up 179+19:53:13 09:22:58
67 processes: 1 running, 66 sleeping
Mem: 484M Active, 1284M Inact, 132M Wired, 58M Cache, 69M Buf, 50M Free
Swap: 2048M Total, 2048M Free
< ... >
Using the values in this example, we can calculate:
Memory utilization = (2048M - 50M - 58M)/2048M = 94.72%
This result is consistent with the output from show chassis routing-engine:
user@router> show chassis routing-engine
Routing Engine status:
Slot 0:
Current state Master
Election priority Master (default)
Temperature 30 degrees C / 86 degrees F
CPU temperature 29 degrees C / 84 degrees F
DRAM 2048 MB
Memory utilization 95 percent
< ... >
Note:, In the above example the memory utilization of 95 percent is not worrying, as there is enough Inactive memory
(1284M Inact); which can be made available by the pageout daemon.
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