After upgrading Server OS from RHEL5.5 to RHEL6.0 nbvault service stopped working.
Which NBU version?
Did you reinstall NBU after upgrading OS?
Supporting Storage Foundation and VCS on Unix and Windows as well as NetBackup on Unix and Windows
Handy NBU Links
Check which license keys installed and wheter Vault feature is active using get_license_key command.
# /usr/openv/netbackup/bin/admincmd/get_license_key -L keys
Authorized Symantec Consultant(ASC) Data Protection in Tokyo, Japan
I agree with Yasuhisa, Need to check license key by using get_license_key .
I think license was expire