No of primary log files is the logfiles which will be allocated during the db activation and the secondary logs are when a transaction requires beyond the no of primary logs secondary logs will be allocated on by one on need basis. the limit to no of logs is logprimary + log secondary. Each log file will be of the file size mentioned in the log file size parameter. Changing teh value of logsecond is dynamic where as logprimary needs a db restart. the max logprimary+log second can be is 256. Let me know if ur doubts are still not clarified.