Archived Redo File Conventions in RAC
| Variable | Description | Example |
|---|---|---|
| %t | Thread number, not padded | log_1 |
| %T | Thread number, left-zero-padded | log_0001 |
| %s | Log sequence number, not padded | log_251 |
| %S | Log sequence number, left-zero-padded | log_0000000251 |
| %r | Resetlogs identifier | log_23452345 |
| %R | Padded resetlogs identifier | log_0023452345 |
| %t_%s_%r | Using multiple variables | log_1_251_23452345 |
For any archived redo log configuration, uniquely identify the archived redo logs with the LOG_ARCHIVE_FORMAT parameter. The format of this parameter is operating system specific and it can include text strings, one or more variables, and a file name extension.
All of the thread parameters, in either uppercase or lowercase, are mandatory for RAC. This enables the Oracle database to create unique names for archive logs across the incarnation. This requirement is in effect when the COMPATIBLE parameter is set to 10.0 or greater. Use the %R or %r parameter to include the resetlogs identifier to avoid overwriting the logs from a previous incarnation. If you do not specify a log format, the default is operating system specific and includes %t, %s, and %r.
As an example, if the instance associated with redo thread number 1 sets LOG_ARCHIVE_FORMAT to log_%t_%s_%r.arc, then its archived redo log files are named as:
log_1_1000_23435343.arc log_1_1001_23452345.arc log_1_1002_23452345.arc ...