MegaRAID Storage Manager software enables you to easily upgrade the controller firmware. To avoid data loss because of dirty cache on the controller, the utility forces the virtual disks into Write through mode after a firmware upgrade. It is in this mode until the server reboots. In Write through mode, the controller sends a data transfer completion signal to the host when the disk subsystem has received all the data in a transaction. This way, in case of a power outage, the controller does not discard the dirty cache.
MegaRAID Storage Manager software displays the version of the existing firmware and the version of the new firmware file. MegaRAID Storage Manager software does not allow you to overwrite a newer version of the firmware with an older version.