3Com VCX V7000 Maintenance Manual page 311

how to determine if a new operating system version was installed and if
so, how to revert to the previous version.
The examples in this step use the assumption that upgrading from version
7.1.x to 7.1.y changed the operating system version from 4.2.0 to 4.2.1.
a Log in as root.
b To determine which operating system versions are available, enter this
command:
vcx-os-query
The output from this command appears:
OS Version
A 4.2.0
B 4.2.1
The operating system versions that you see may vary from the example
shown.
The order of the A and B versions may be reversed depending on the
upgrade history of the system.
When you are downgrading, use the earlier of the two operating system
versions in this command:
vcx-os-switch 4.2.0
To confirm that you have selected the operating system version that you
want, repeat the
"selected" appears in the Status column for the version that you want.
Example:
OS Version
A 4.2.0
B 4.2.1
4 Reboot the system using this command:
reboot
When the system reboots, it starts VCX 7.1.x services.
Partition
/dev/hda2
/dev/hda3
command. Verify that the word
vcx-os-query
Partition
/dev/hda2
/dev/hda3
Downgrading from 7.1.y to 7.1.x
Label
/A
/B
Label
/A
/B
311
Status
active
Status
selected
active