Use LOG_ARCHIVE_FORMAT to specify the default filename format when archiving redo log files.

Property Description

Parameter type




Default value

Operating system-dependent



Modifiable in a PDB


Range of values

Any string that resolves to a valid filename



Oracle RAC

Multiple instances can have different values, but identical values are recommended.

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'

Archive log file names must contain each of the elements %s (sequence), %t (thread), and %r (resetlogs ID) to ensure that all archive log file names are unique. If the LOG_ARCHIVE_FORMAT initialization parameter is set in the parameter file, then make sure the parameter value contains the %s, %t, and %r elements. Otherwise, the following error is displayed at the time of instance startup:

ORA-19905: log_archive_format must contain %s, %t and %r

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.

LOG_ARCHIVE_FORMAT is ignored in these cases:

  • For archived log files that go to the fast recovery area

  • When LOG_ARCHIVE_DEST[_n] points to the root of an Oracle ASM disk group (for example, +DATA). The directory of a disk group (for example, +DATA/logs) must be specified for the parameter to be honored.

In these cases where LOG_ARCHIVE_FORMAT is ignored, an Oracle ASM file name is used. See Oracle Automatic Storage Management Administrator's Guide for more information on Oracle ASM file names.

See Also: