3com database adapter module for networker nsr-ora v3.2 User Manual

System Administrator’s Guide

U42252-J-Z915-1-76

Introduction

these redolog files had already been saved on the backup medium by the 
archiving monitor and then automatically deleted, they will be read in again and 
reapplied until the database is up to date. The database is then opened and is 
again ready for normal operation. The recovery is triggered by the ora_recut and 
nsrora_rec

 commands and proceeds automatically; a knowledge of ORACLE is 

not necessarily required for this (see also chapter 

).

Physical faults that bring normal database operation to a halt basically fall into 
the following four categories:

●

loss of a (all) control file(s)

●

loss of a current online redolog file

●

loss of files containing system data

●

loss of files containing user data.

As a rule, the loss of a control file does not pose major problems because the 
control file can be mirrored at the software level using the control_files parameter 
in the ORACLE parameter file init<ORACLE_SID>.ora. ORACLE strongly 
recommends saving at least two copies of the control file on different disks. We 
agree with this recommendation.

The loss of a current online redolog file is also precluded almost completely by 
mirroring (at the software level by ORACLE or at the hardware level by mirror 
disks). 

   For this reason, neither of these fault categories (loss of the control file 

and loss of current online redolog files) is taken into account during an 
automatic

 recovery of the database. Only in recovery until time with 

 is the relevant control file also recovered. Nor is NSR-ORA in a 

position to recognize or correct logical database errors (for instance, if 
incorrect files are loaded into the database).

The ORACLE Administrator Guide explains what you can do if you should lose 
the control file and/or a number of redolog files. You can also refer to the chapter 

 of this manual, which describes the restrictions that apply to 

automatic recovery for ORACLE Parallel Server (OPS) systems.

In the other two cases (loss of files containing system or user data), NSR-ORA 
offers various ways of recovering the data: fully automatic or manual recovery 
or restore of a specific database level (recovery until time).