Q:
An AP can crash due to various reasons and when the AP crashes due to kernel panic, we generate a kernel panic file from AP which is sent to the dump server configured in the controller after the AP is rebooted. Before the system reboots, AP will generate files relating ro crash such as stack back traces, register dumps and printk log messages and stores them on the flash. However the AP doesn't collect the panic-dump file which is important to understand the cause of the kernel panic crash.
A: Starting with 802.11AX AP's (AP-555 and 535), a new feature has been implemented called "KDump" which will extract the full system memory in two steps. This full system memory will contain the "panic dump" file which contains crucial information relating to the reason for the kernel panic crash.
In order to achieve this, we have to configure, dump-server-profile with transport mode set to SCP. Before we go ahead and configure the "dump-server-profile", we must ensure the below prerequisites are taken care of.
Prerequisites:
- Setup SCP in the laptop (Preferably Linux based) where the AP sends the dump when the AP crashes
- Ensure the AP has reachability to the laptop by doing a ping or copying a file from controller to the laptop using SCP
- SCP is the only transport mode protocol used by the "KDump" feature.
- Ensure that "transport-mode" SCP is configured when "System-Dump" is enabled
- Due to memory limitations restricted to 32MB, transport mode "TFTP" won't be able to copy all the files such as System Dump
- "Server path" is your absolute path. Please start with a "/".
Controller Configuration CLI:
(LAB-Primary-MM) [11ax-Cluster] (config) #dump-collection-profile 11ax
(LAB-Primary-MM) ^[11ax-Cluster] (Dump collection profile "11ax") #dump-collection-profile 11ax
(LAB-Primary-MM) ^[11ax-Cluster] (Dump collection profile "11ax") #transfer-mode scp
Warning: SCP Transfer Mode is only supported on AP-5xx
(LAB-Primary-MM) ^[11ax-Cluster] (Dump collection profile "11ax") #transfer-mode scp
(LAB-Primary-MM) ^[11ax-Cluster] (Dump collection profile "11ax") #server-ip 10.28.10.116
(LAB-Primary-MM) ^[11ax-Cluster] (Dump collection profile "11ax") #server-username test
(LAB-Primary-MM) ^[11ax-Cluster] (Dump collection profile "11ax") #server-password aruba123
(LAB-Primary-MM) ^[11ax-Cluster] (Dump collection profile "11ax") #server-path /users/test/SCP
(LAB-Primary-MM) ^[11ax-Cluster] (Dump collection profile "11ax") #system-dump-enable
(LAB-Primary-MM) ^[11ax-Cluster] (Dump collection profile "11ax") #write memory
Saving Configuration...
Configuration Saved.
Execute the below command to verify the profile is configured:
(LAB-Cluster-1) [MDC] #show dump-collection-profile 11ax
Dump collection profile "11ax"
------------------------------
Parameter Value
--------- -----
Transfer Mode SCP
Server IP 10.28.10.116
Server Port 22
Server Username test
Server Password ********
Server Path /users/test/SCP
System Dump Enabled
(LAB-Cluster-1) [MDC] #
Controller Configuration: webUI
Post configuring, in the event of AP reboot due to kernel panic, AP will generate 5 files as seen below and send it to the SCP server before it's rebooted.
Once the AP comes back up after reboot, it will generate 'panic-dump' file which is the crucial part of the "KDumo" feature and will send it to the SCP server.
