code: private void readFileHeader()
      {
          if (tc.isEntryEnabled())
              Tr.entry(tc, "readFileHeader", this);
  
          // Reset the current header information. Once reset has executed, the header
          // is marked as invalid and will only become valid again once a correctly 
          // formatted header has been read from the disk.
          _logFileHeader.reset();
  
          // Read the header, ignoring any failures. Failures will be detected later
          // when _logFileHeader.status() method returns STATUS_INVALID.
          try
          {
              // Ensure that there is sufficient capacity to read the integer header
              // size field before proceeding. If there is not then exit directly. This
              // header will remain marked as inactive.
              if (_fileBuffer.capacity() >= RLSUtils.INT_SIZE)
              {
                  _logFileHeader.read(_fileBuffer);
              }
          } catch (Throwable exc)
          {
              FFDCFilter.processException(exc, "com.ibm.ws.recoverylog.spi.LogFileHandle.readFileHeader", "863", this);
              if (tc.isEventEnabled())
                  Tr.event(tc, "The log header could not be read from the disk due to an unexpected exception");
              // There in incomplete or invalid header. No action is required here as the log header is still
              // marked as invalid.
          }
  
          if (tc.isEntryEnabled())
              Tr.exit(tc, "readFileHeader");
      }
docs: Read the header data from the file managed by this LogFileHandle instance. Any
  failure that occurs will result in the log file header ('_logFileHeader')
  being marked as invalid. This can then be tested later by calling the
  _logFileHeader.status() method and comparing for STATUS_INVALID.