Central Inventory contains information relating to all Oracle products that are installed on a host. It contains an inventory file and a logs subfolder that contains OUI and OPatch logs.
In a Windows environment, Central Inventory is in System drive/program files/Oracle/inventory.
In a UNIX environment, the Central Inventory location is specified in the oraInst.loc file, which is generally in the /etc folder.
Central Inventory log files are generally saved in this format:
ActionTimestamp.log
For example, this log is recorded for an attachHome operation performed on May 17, 2010, at 6.45AM:
AttachHome2010-05-17_06-45-00AM.log