Trying to update BIOS on Dell PowerEdge server running CentOS Linux may fail to complete with no further explanation even if all software requirement has been met do do the upgrade from the OS.
This is because Dell does not recognize CentOS (which is a 100% RedHat binary compatible) as a supported OS (such as Red Hat Enterprise Linux).
The workaround is to fake the OS name to pretend to be RedHat. To do so, just edit the following file :
/etc/redhat-release
And modify the line (ex : CentOS release 5.7 (Final)) to be :
Red Hat Enterprise Linux Server release 5.7 (Final)
Then, run the BIOS update script and it should work.