131
Performing an ISSU
Unless otherwise stated, the term "upgrade" refers to both software upgrade and downgrade in
ISSU.
Overview
The In-Service Software Upgrade (ISSU) feature upgrades software with a minimum amount of
downtime.
ISSU is implemented on the basis of the following design advantages:
•
Separation of service features from basic functions
—Device software is segmented into
boot, system, and feature images. The images can be upgraded individually.
•
Independence between service features
—Features run independently. One feature can be
added or upgraded without affecting the operation of the system or other features.
•
Support for hotfix
—Patch images are available to fix system bugs without a system reboot.
•
Hardware redundancy
—On a dual-MPU device or a multichassis IRF fabric, one MPU or
member device can be upgraded while other MPUs or member devices are providing services.
For more information about images, see "
."
ISSU methods
ISSU methods are automatically determined depending on the compatibility between software
versions.
ISSU supports the following upgrade types:
•
Compatible upgrade
—The running software version is compatible with the new software
version. This upgrade type supports the ISSU methods in
•
Incompatible upgrade
—The running software version is incompatible with the new software
version. The two versions cannot run concurrently.
This upgrade type supports only one upgrade method (also called incompatible upgrade). This
method requires a cold reboot to upgrade both control and data planes. Incompatible upgrade
disrupts service if hardware redundancy is not available.
For information about identifying the ISSU method, see "
Identifying the software image
command to display the software image
signature information. The signature of a software image might be HP, HP-US, or HPE.
Table 13 ISSU methods for compatible upgrade
ISSU method
Description
Incremental upgrade:
•
Service Upgrade
•
File Upgrade
Upgrades only user mode processes that have differences between the new and
old software versions. Backup processes and a main/backup process switchover
are required for service continuity.
•
Service upgrade
—Upgrades service features. The upgrade does not affect
the operation of the features that are not being upgraded.
•
File upgrade
—Upgrades hidden system program files. The system can
provide services during the upgrade.
Summary of Contents for FlexNetwork 10500 Series
Page 139: ...130 Sysname display version ...