Description

 This article describes the issue of the messages logs being filled up with CHASSISD_BLOWERS_SPEED_MEDIUM messages.

Symptoms

After upgrading from 10.4R6 to 10.4R9, The following log messages are generated in chassisd:

Logs from chassis after upgrading to 10.4R9 :

May 21 09:47:36 CHASSISD_BLOWERS_SPEED_MEDIUM: Fans and impellers being set to intermediate speed
May 21 09:51:36 CHASSISD_BLOWERS_SPEED_MEDIUM: Fans and impellers being set to intermediate speed
May 21 09:56:16 CHASSISD_BLOWERS_SPEED_MEDIUM: Fans and impellers being set to intermediate speed
May 21 10:00:56 CHASSISD_BLOWERS_SPEED_MEDIUM: Fans and impellers being set to intermediate speed
May 21 10:06:57 CHASSISD_BLOWERS_SPEED_MEDIUM: Fans and impellers being set to intermediate speed
Logs prior to upgrading (on 10.4R6) :
Oct 3 06:04:03 CHASSISD_BLOWERS_SPEED: Fans and impellers are now running at normal speed
Oct 3 07:12:27 CHASSISD_BLOWERS_SPEED: Fans and impellers are now running at normal speed
Oct 3 08:18:11 CHASSISD_BLOWERS_SPEED: Fans and impellers are now running at normal speed
Oct 3 09:25:35 CHASSISD_BLOWERS_SPEED: Fans and impellers are now running at normal speed

Solution

There have been some improvements made to the thermal management on SRX3000 series from 11.4R2, 12.1R1, 10.4R9, 11.1R7, and 11.2R4.

The chassis management daemon (chassisd) uses the temperature sensor readings to make decisions, as to when to change the fan speed. For all releases, prior to 11.4R2, 12.1R1, 10.4R9, 11.1R7, and 11.2R4, there were only 2 levels for the fan speed - normal and high.

From the 11.4R2, 12.1R1, 10.4R9, 11.1R7, and 11.2R4 releases, changes were made on the thermal management for SRX3000 series to increase the number of levels of fan speed from 2 to 3 levels; that is normal, intermediate, and high.

The fan speed will change from normal to intermediate, when the XLR temperature is above 60 degress celsius. For example:

root@B> show chassis environment | match XLR
   FPC 8 XLR                      OK         61 degrees C / 141 degrees F
   FPC 9 XLR                      OK         64 degrees C / 147 degrees F
 

The thresholds for temperature adjustment from this change are as follows:

Normal to Intermediate  : XLR heated to 60C
Intermediate to Full        : XLR heated to 75C
Full to Intermediate        : XLR cooled down to 65C
Intermediate to Normal  : XLR cooled down to 55C

However, based on feedback, the chassisd logs are now too verbose with the CHASSISD_BLOWERS_SPEED_MEDIUM messages filling up the log files.

From the 10.4R11, 11.4R5, and 12.1R3 releases, the following log message, which indicate the fan speed change from normal to intermediate, will be suppressed:
May 21 09:47:36 CHASSISD_BLOWERS_SPEED_MEDIUM: Fans and impellers being set to intermediate speed

Modification History

2020-07-23: Archived.