Understanding CacheFlow Restarts

Products

• CacheFlow Appliance Software

Issue/Introduction

There may be times when the CacheFlow appliance needs to be restarted. Restarts are required when upgrading software, during some hardware maintenance or, occasionally, to assist in troubleshooting a problem. This document describes the different types of restarts and their purposes. 

Questions answered:

• What is the difference between cold and warm restart?
• What is ‘restart abrupt’ and under what circumstances should it be used?

Resolution

There are five types of restart: regular (hardware or software), upgrade (hardware only) and abrupt (hardware or software).

A hardware restart shuts down the appliance and gives control to the BIOS. It is a complete hardware reset equivalent to power-cycling the appliance. During a hardware restart, the user is given the option to select an image to boot. A hardware restart is also called a cold boot.

A software restart is done completely in CacheFlow software and is much quicker than a hardware restart. Because the software is not halted, a new image cannot be loaded. A software restart is also called a warm boot.

By default, CacheFlow appliances will employ a software restart:

Blue Coat CacheFlow 5000 Series>show restart 
Restart settings
 Restart:     software only
 Core image: context only
 Compression: disabled

 

Hardware or software restart can be chosen in the restart menu at the config prompt: 

Blue Coat CacheFlow 5000 Series#(config)restart mode ?
 hardware                     Set for hardware restart
 software                     Set for software only restart

 

This setting only affects the restart regular or restart abrupt commands. Restart upgrade is always a hardware restart and cannot be modified.

 

Restart regular is the typical restart. To issue a restart regular, execute the command from the enable prompt: 

Blue Coat CacheFlow 5000 Series#restart regular
 restart regular initiated ...
Initiating a software only restart
Waiting for disk activity to cease

 

 

The other types of restarts can be invoked in the same way: 

Blue Coat CacheFlow 5000 Series#restart ?
 abrupt                       Reboot system abruptly, according to restart settings
 regular                      Reboot system according to restart settings
 upgrade                      Reboot system to start running new image

 

Restart upgrade is typically executed after a ‘load upgrade’ command, which loads a new software image and pre-selects it as the default.

 

Restart abrupt sends an interrupt to shutdown the appliance immediately. It does not wait for disk activity to end. A restart abrupt will perform a hardware or software restart depending on what the restart mode is set to. Restart abrupt essentially mimics a crash, and writes out important diagnostic information; for this reason, Blue Coat support may sometimes request a restart abrupt in order to obtain valuable information about a support case.

 

From the serial console only, the command sequence ctrl-X ctrl-C  will cause an immediate abrupt hardware restart; This sequence should only be used if other CLI sessions become non-responsive.

After a restart, the type can be determined by the message on startup. For example, a software restart:

 

 

A hardware restart will go through a full bootup including a BIOS check and an option list of available systems. Afterwards, the system restart message will be displayed:

 

These messages are also logged to syslog and can be viewed in the GUI: