WiSM crash with no crash log

Question

Guys,
I have many WiSM WLC's running 7.0.116.0. One WLC was rebooted few days ago but there was no crash file and nothing in logs say why this issue happened.
There was a power problem at the same time the WLC rebooted (some switches and PE's was rebooted as well) but if it is a power issue why only one WLC inside the WiSM rebooted and the other WLC is still working fine with no reboot?
I have 5 WiSM modules connected to the same 6500 box, only one WLC was rebooted which indicates a crash but no crash file registered for it.
Is there anyway I can find the reason why that WLC was rebooted?
Could it be a power issue over all? if yes what about my concerns above?
Thanks.
Amjad

Answer 1

Amjad,
What is the power supply model you have in your 6500?
Do you have 1 power supply or 2?
If 2, are you running them in combined mode or redundant mode?
These questions are specific to the behavior of the 6500 in the event of a partial power loss, such as a failing power supply or loss of current from the mains.
The following is an excerpt from the 6500 Operational Best Practices guide:
2.10 Power Shutdown Sequence
The previous section highlighted the recommendation for running in redundant mode. Should there be a requirement to run in combined mode, an extra precaution needs to be taken. In the event of a failing power supply that leaves the system without enough power to
drive the total configuration, inline devices and line cards will be shut down by the power management software to fall within operating power capabilities.
In order for the user to recognize the event and its consequences, the shutdown sequence logic should be known and understood: in particular, the Catalyst 6500 control software will first start to power down inline devices from the highest numbered port to the lowest numbered port, then from the bottom slot up. If after powering down all inline devices there is still insufficient power, the system will start to power down line cards from the bottom slot up with the exception of the supervisor module and of the services modules (that is, firewall module, VPN module, IDS module, and so on). Supervisor and services modules are the last modules left operating. For this reason, important hosts should be plugged into ports on the top-most modules (that is, slots 1, 2, 3, and so on) and from the lower numbered ports up. It is worth noting that the order of shutdown is fixed by the system and cannot be changed.
While this exceprt specifically says that SUPs and service modules are the last operating modules in a low power condition, I am curious if you had a condition wherein the 6500 made the decision to power down one of your wisms because power was too low to support all 5 plus the Sup(s).
Justin