SAP Note 21568 - SAPDBA: Warning: only one member of online redo log

Symptom:

SAPDBA returns the following messages when started:
1. "SAPDBA: Warning - there is only one control file
specified in the init.ora!
For security reason you must mirror the control file!"

2. "SAPDBA: The combination of database log mode: archivelog
and automatic archival: disabled
will cause an archiver stuck ->
Please, change this situation by using:
Archive mode->toggle automatic archival"

3. "SAPDBA: Warning - there is only one member
of online redo log group !
For security reason you must mirror those groups
that have only one member."

Cause and prerequisites

If "init.dba" switch "check_initial_settings Y" is set in the sapdba profile, (default, to 2.2E is "N", not set, after this, the default is "Y"), the following are checked every time SAPDBA is started:

1. The existence of at least one mirrored copy of the control file,
2. Combination of "Database log mode" and "Automatic archiving",
3. The existence of at least one backup copy for each online redo log group (that is at least 2 members of each mirrored group).

SAPDBA returns a warning if one or more of the required conditions are not met. The initial menu first appears after entering .

Solution
The warnings do not affect the functionality of sapdba; they do, however, indicate possible security gaps in the database.

Re 1. and 3.:
You should perform a software mirror as soon as possible, esp. if you are not already using hardware mirroring. However, mirroring this special file is also recommended--even when hardware mirroring is already being done--because the files are not very large (esp. in #1). Harware mirroring does not protect against the accidental manual deletion of a file.

Re 2:
Ignoring this message can cause "Archiver Stuck", that is, the database goes into the wait state until it can execute a "Log switch" again.

It is possible to switch off the checks with "check_initial_settings N" in the profile.
As of version 3.0A, checks 1 and 3 can be activated or deactived individually with the following switches ("Y" or "N" performs the selection):
"check_controlfile_mirror" or "check_redolog_mirror"

Additional key words

control file redo log mirror