LOG_ARCHIVE_FORMAT is applicable only if you are using the redo log in ARCHIVELOG mode.
Use a text string and variables to specify the default filename format when archiving redo log files. The string generated from this format is appended to the string specified in the LOG_ARCHIVE_DEST parameter.
The following variables can be used in the format:
%s log sequence number
%S log sequence number, zero filled
%t thread number
%T thread number, zero filled
%a activation ID
%d database ID
%r resetlogs ID that ensures unique names are constructed for the archived log files across multiple incarnations of the database
Using uppercase letters for the variables (for example, %S) causes the value to be fixed length and padded to the left with zeros. An example of specifying the archive redo log filename format follows:
LOG_ARCHIVE_FORMAT = 'log%t_%s_%r.arc'
Neither LOG_ARCHIVE_DEST nor LOG_ARCHIVE_FORMAT have to be complete file or directory specifiers themselves;
they only need to form. a valid file path after the variables are substituted into LOG_ARCHIVE_FORMAT and the two parameters are concatenated together.
