Archive for category TOI
When using the Data Guard Broker, you don’t need to set any LOG_ARCHIVE_* parameter for the databases that are part of your Data Guard configuration. The broker is doing that for you. Forget about what you may have heard about VALID_FOR – you don’t need that with the broker. Actually, setting any of the LOG_ARCHIVE_* parameters with an enabled broker configuration might even confuse the broker and lead to warning or error messages. Let’s look at a typical example about the redo log transport mode. There is a broker configuration enabled with one primary database prima and one physical standby physt. The broker config files are mirrored on each site and spfiles are in use that the broker (the DMON background process, to be precise) can access:
When connecting to the broker, you should always connect to a DMON running on the primary site. The only exception from this rule is when you want to do a failover: That must be done connected to the standby site. I will now change the redo log transport mode to sync for the standby database. It helps when you think of the log transport mode as an attribute (respectively a property) of a certain database in your configuration, because that is how the broker sees it also.
[oracle@uhesse1 ~]$ dgmgrl sys/oracle@prima DGMGRL for Linux: Version 126.96.36.199.0 - 64bit Production Copyright (c) 2000, 2009, Oracle. All rights reserved. Welcome to DGMGRL, type "help" for information. Connected. DGMGRL> edit database physt set property logxptmode=sync; Property "logxptmode" updated
In this case, physt is a standby database that is receiving redo from primary database prima, which is why the LOG_ARCHIVE_DEST_2 parameter of that primary was changed accordingly:
[oracle@uhesse1 ~]$ sqlplus sys/oracle@prima as sysdba SQL*Plus: Release 188.8.131.52.0 Production on Tue Sep 30 17:21:41 2014 Copyright (c) 1982, 2011, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 184.108.40.206.0 - 64bit Production With the Partitioning, OLAP and Data Mining options SQL> show parameter log_archive_dest_2 NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ log_archive_dest_2 string service="physt", LGWR SYNC AFF IRM delay=0 optional compressi on=disable max_failure=0 max_c onnections=1 reopen=300 db_uni que_name="physt" net_timeout=3 0, valid_for=(all_logfiles,pri mary_role)
The mirrored broker configuration files on all involved database servers contain that logxptmode property now. There is no new entry in the spfile of physt required. The present configuration allows now to raise the protection mode:
DGMGRL> edit configuration set protection mode as maxavailability; Succeeded.
The next broker command is done to support a switchover later on while keeping the higher protection mode:
DGMGRL> edit database prima set property logxptmode=sync; Property "logxptmode" updated
Notice that this doesn’t lead to any spfile entry; only the broker config files store that new property. In case of a switchover, prima will then receive redo with sync.
DGMGRL> show configuration; Configuration - myconf Protection Mode: MaxAvailability Databases: prima - Primary database physt - Physical standby database Fast-Start Failover: DISABLED Configuration Status: SUCCESS DGMGRL> switchover to physt; Performing switchover NOW, please wait... New primary database "physt" is opening... Operation requires shutdown of instance "prima" on database "prima" Shutting down instance "prima"... ORACLE instance shut down. Operation requires startup of instance "prima" on database "prima" Starting instance "prima"... ORACLE instance started. Database mounted. Switchover succeeded, new primary is "physt"
All I did was the switchover command, and without me specifying any LOG_ARCHIVE* parameter, the broker did it all like this picture shows:
[oracle@uhesse2 ~]$ sqlplus sys/oracle@physt as sysdba SQL*Plus: Release 220.127.116.11.0 Production on Tue Oct 14 15:43:41 2014 Copyright (c) 1982, 2011, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 18.104.22.168.0 - 64bit Production With the Partitioning, OLAP and Data Mining options SQL> show parameter log_archive_dest_2 NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ log_archive_dest_2 string service="prima", LGWR SYNC AFF IRM delay=0 optional compressi on=disable max_failure=0 max_c onnections=1 reopen=300 db_uni que_name="prima" net_timeout=3 0, valid_for=(all_logfiles,pri mary_role)
Not only is it not necessary to specify any of the LOG_ARCHIVE* parameters, it is actually a bad idea to do so. The guideline here is: Let the broker control them! Else it will at least complain about it with warning messages. So as an example what you should not do:
[oracle@uhesse1 ~]$ sqlplus sys/oracle@prima as sysdba SQL*Plus: Release 22.214.171.124.0 Production on Tue Oct 14 15:57:11 2014 Copyright (c) 1982, 2011, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 126.96.36.199.0 - 64bit Production With the Partitioning, OLAP and Data Mining options SQL> alter system set log_archive_trace=4096; System altered.
Although that is the correct syntax, the broker now gets confused, because that parameter setting is not in line with what is in the broker config files. Accordingly that triggers a warning:
DGMGRL> show configuration; Configuration - myconf Protection Mode: MaxAvailability Databases: physt - Primary database prima - Physical standby database Warning: ORA-16792: configurable property value is inconsistent with database setting Fast-Start Failover: DISABLED Configuration Status: WARNING DGMGRL> show database prima statusreport; STATUS REPORT INSTANCE_NAME SEVERITY ERROR_TEXT prima WARNING ORA-16714: the value of property LogArchiveTrace is inconsistent with the database setting
In order to resolve that inconsistency, I will do it also with a broker command – which is what I should have done instead of the alter system command in the first place:
DGMGRL> edit database prima set property LogArchiveTrace=4096; Property "logarchivetrace" updated DGMGRL> show configuration; Configuration - myconf Protection Mode: MaxAvailability Databases: physt - Primary database prima - Physical standby database Fast-Start Failover: DISABLED Configuration Status: SUCCESS
Thanks to a question from Noons (I really appreciate comments!), let me add the complete list of initialization parameters that the broker is supposed to control. Most but not all is LOG_ARCHIVE*
The single most important factor for successful digital learning is the attitude both of the instructor as well as of the attendees towards the course format. Delivery of countless Live Virtual Classes (LVCs) for Oracle University made me realize that. There are technical prerequisites of course: A reliable and fast network connection and the usage of a good headset is mandatory, else the participant is doomed from the start. Other prerequisites are the same as for traditional courses: Good course material, working lab environment for hands on practices and last not least knowledgeable instructors. For that part notice that we have the very same courseware, lab environments and instructors like for our classroom courses at Oracle University education centers also for LVCs. The major difference is in your head :-)
Delivering my first couple of LVCs, I felt quite uncomfortable with that new format. Accordingly, my performance was not as good as usual. Meanwhile, I consider the LVC format as totally adequate for my courses and that attitude enables me to deliver them with the same performance as my classroom courses. Actually, they are even better to some degree: I always struggle producing clean sketches with readable handwriting on the whiteboard. Now look at this MS paint sketch from one of my Data Guard LVCs:
Attendees get all my sketches per email if they like afterwards.
In short: Because I’m happy delivering through LVC today, I’m now able to do it with high quality. The attitude defines the outcome.
Did you ever have a teacher in school that you just disliked for some reason? It was hard to learn anything from that teacher, right? Even if that person was competent.
So this is also true on the side of the attendee: The attitude defines the outcome. If you take an LVC thinking “This cannot work!”, chances are that you are right just because of your mindset. When you attend an LVC with an open mind – even after some initial trouble because you need to familiarize yourself with the learning platform and the way things are presented there – it is much more likely that you will benefit from it. You may even like it better than classroom courses because you can attend from home without the time and expenses it takes to travel :-)
Some common objections against LVC I have heard from customers and my usual responses:
An LVC doesn’t deliver the same amount of interaction like a classroom course!
That is not necessarily so: You are in a small group (mostly less than 10) that is constantly in an audio conference. Unmute yourself and say anything you like, just like in a classroom. Additionally, you have a chatbox available. This is sometimes extremely helpful, especially with non-native speakers in the class :-) You can easily exchange email addresses using the chatbox as well and stay in touch even after the LVC.
I have no appropriate working place to attend an LVC!
You have no appropriate working place at all, then, for something that requires a certain amount of concentration. Talk to your manager about it – maybe there is something like a quiet room available during the LVC.
I cannot keep up the attention when starring the whole day on the computer screen!
Of course not, that is why we have breaks and practices in between the lessons.
Finally, I would love to hear about your thoughts and experiences with online courses! What is your attitude towards Digital Learning?
On Thursday, 2nd October, 12:30 CET I will be doing a Live Webcast with many demonstrations about Data Guard Real-Time Query.
The shown features all work with 11g already.