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EX2200/EX3200 may experience low memory warnings

  [TSB16779] Show Article Properties


Alert Type:
PSN - Product Support Notification
Product Affected:
EX2200, EX3200 families of products
Alert Description:

Low available memory warnings (if less than 20% by default) may be logged on EX2200 and EX3200 switches.  Example:
Jul 4 13:05:43 switch /kernel: Percentage memory available(19)less than threshold(20 %)- 3
Jul 4 13:32:43 switch /kernel: Percentage memory available(19)less than threshold(20 %)- 4
Jul 4 14:20:33 switch /kernel: Percentage memory available(19)less than threshold(20 %)- 5
Jul 8 15:05:39 switch /kernel: Percentage memory available(18)less than threshold(20 %)- 11
The probability of this happening increases with newer versions of Junos, which require more memory in operation, particularly versions 12.3 and later.

EX2200 and EX3200 switches have 512MB of total memory, whereas other switches have 1GB or more.

There is no immediate service impact to the switch as a result of these messages, and can be safely ignored.  Memory utilization should be monitored.  If the available memory drops below 10%, then investigate the possibility of disabling features, reducing routing table sizes, etc.

At the 5% threshold, critical memory messages may be logged:

/kernel: KERNEL_MEMORY_CRITICAL: System low on free memory, notifying init (#1).
rpd[1255]: Processing low memory signal

At this point, automatic corrective actions can take place.  Service impact is expected.

As long as free memory does not fall below the 5% threshold, the switch operates normally.

This issue is tracked by PR900030



Solution:

Here are some steps one can undertake on the EX2200/EX3200:
  1. Monitoring memory utilization to not going below 5%
  2. Disable unneeded features.  Examples could include Web-management
  3. In order to reduce switch memory usage, we can limit the number of concurrent telnet/ssh users.  Each session uses additional memory
  4. Open TAC case if memory warnings still show up after above actions are tried

Implementation:

1. Unconfigure features which are not mission critical.  Reduce routing/switching table sizes if possible.  It may help to reboot the system.

2. Limit the number of concurrent users on the switch.  Suggested limit is 1 or 2.

connection-limit



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