Symantec NetBackup Appliance 5230 cannot launch jviewer for ipmi

You need JRE. Please download and install.

http://www.oracle.com/technetwork/java/javase/downloads/jre7-downloads-1880261.html

If it is already installed then you need to check the Java security settings.

Some of other requirements - 

You can use a Web browser to access the NetBackup Appliance Web Console or
the IPMI console. The following requirements and recommendations should be
considered for the Web browser:
■ The NetBackup Appliance Web Console and the IPMI console use pop-up
menus. If you use pop-up blockers with your Web browser, some of these menus
may not display properly. You must disable pop-up blocking or add the Appliance
Web address to the list of acceptable sites in your browser.
■ The Web browser should have active scripting (ActiveX and JavaScript) enabled.
■ On some server-class systems, an enhanced security configuration can cause
some pages to not display properly in Internet Explorer. If you encounter this
issue, add the Appliance Web Console to the Trusted-sites list and lower the
security setting. To resolve this issue, open Internet Explorer and select Tools
> Internet Options > Security to configure the Trusted-sites list and lower the
security level.
■ If you use Internet Explorer 9.0 or above to access the Appliance Web console,
security certificate warnings appear when you access a pop-up menu. Select
Continue to this web site (not recommended) to log on to the appliance.
Once you select this option, the security certificate warnings do not appear on
the pop-up menus.
■ The NetBackup Appliance Web Console is best viewed with 1280 * 1024 or a
higher screen resolution.