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Posted in TOI on December 7, 2018
During the Data Guard round table of the excellent UKOUG Tech18 conference I got aware of this topic that I’d like to share with the Oracle community:
What is the locking behavior for user accounts in an environment where users may connect to the primary as well as to the standby database?
User gets locked on the primary
SQL> alter profile default limit failed_login_attempts 2; Profile altered. SQL> create user adam identified by adam; User created. SQL> grant create session to adam; Grant succeeded. SQL> connect adam/wrong@prima ERROR: ORA-01017: invalid username/password; logon denied Warning: You are no longer connected to ORACLE. SQL> connect adam/wrong@prima ERROR: ORA-01017: invalid username/password; logon denied SQL> connect adam/wrong@prima ERROR: ORA-28000: The account is locked.
I changed the default profile so the account lock happens faster. The change of the default profile reaches the standby via redo apply. The same goes for account locks that happened on the primary like above.
Standby inherits the locked accounts from primary
SQL> connect adam/wrong@physt ERROR: ORA-28000: The account is locked.
This inherited lock cannot be unlocked on the standby:
SQL> connect sys/oracle@physt as sysdba Connected. SQL> alter user adam account unlock; alter user adam account unlock * ERROR at line 1: ORA-28015: account unlock attempted on read-only database but a conflicting account lockout on the primary exists
The account can only be unlocked on the primary and that implictly unlocks it on the standby too:
SQL> connect sys/oracle@prima as sysdba Connected. SQL> alter user adam account unlock; User altered. SQL> connect adam/adam@prima Connected. SQL> connect adam/adam@physt Connected.
Account gets locked on the standby only
SQL> connect adam/wrong@physt ERROR: ORA-01017: invalid username/password; logon denied Warning: You are no longer connected to ORACLE. SQL> connect adam/wrong@physt ERROR: ORA-01017: invalid username/password; logon denied SQL> connect adam/wrong@physt ERROR: ORA-28000: The account is locked.
This lock at the standby is kept there in memory only and doesn’t impact the primary:
SQL> connect adam/adam@prima Connected.
It can be unlocked on the standby:
SQL> connect sys/oracle@physt as sysdba Connected. SQL> alter user adam account unlock; User altered. SQL> connect adam/adam@physt Connected.
Standby locks are kept in memory
After a restart, the lock is gone:
SQL> connect adam/wrong@physt ERROR: ORA-01017: invalid username/password; logon denied Warning: You are no longer connected to ORACLE. SQL> connect adam/wrong@physt ERROR: ORA-01017: invalid username/password; logon denied SQL> connect adam/wrong@physt ERROR: ORA-28000: The account is locked. SQL> connect sys/oracle@physt as sysdba Connected. SQL> shutdown immediate Database closed. Database dismounted. ORACLE instance shut down. SQL> startup ORACLE instance started. Total System Global Area 629143384 bytes Fixed Size 8660824 bytes Variable Size 180355072 bytes Database Buffers 436207616 bytes Redo Buffers 3919872 bytes Database mounted. Database opened. SQL> connect adam/adam@physt Connected.
Role change involving a restart of the standby
That will also lose the previous locks that have been done at the standby only:
SQL> connect adam/wrong@physt ERROR: ORA-01017: invalid username/password; logon denied Warning: You are no longer connected to ORACLE. SQL> connect adam/wrong@physt ERROR: ORA-01017: invalid username/password; logon denied SQL> connect adam/wrong@physt ERROR: ORA-28000: The account is locked. SQL> exit [oracle@uhesse ~]$ dgmgrl sys/oracle@prima DGMGRL for Linux: Release 220.127.116.11.0 - Production on Fri Dec 7 08:28:59 2018 Version 18.104.22.168.0 Copyright (c) 1982, 2018, Oracle and/or its affiliates. All rights reserved. Welcome to DGMGRL, type "help" for information. Connected to "prima" Connected as SYSDBA. DGMGRL> switchover to physt; Performing switchover NOW, please wait... Operation requires a connection to database "physt" Connecting ... Connected to "physt" Connected as SYSDBA. New primary database "physt" is opening... Operation requires start up of instance "prima" on database "prima" Starting instance "prima"... Connected to an idle instance. ORACLE instance started. Database mounted. Database opened. Connected to "prima" Switchover succeeded, new primary is "physt" DGMGRL> show configuration; Configuration - myconf Protection Mode: MaxPerformance Members: physt - Primary database prima - Physical standby database Fast-Start Failover: DISABLED Configuration Status: SUCCESS (status updated 18 seconds ago) DGMGRL> exit [oracle@uhesse ~]$ sqlplus /nolog SQL*Plus: Release 22.214.171.124.0 - Production on Fri Dec 7 08:31:16 2018 Version 126.96.36.199.0 Copyright (c) 1982, 2018, Oracle. All rights reserved. SQL> connect adam/adam@prima Connected. SQL> connect adam/adam@physt Connected.
I did the tests on 18c but I don’t think this is a new feature. I just didn’t have that topic on the radar before. Which is one reason why we go to conferences, right? 🙂
Posted in TOI on November 23, 2018
As every year in November, the database circus moved to Nuremberg on behalf of the annual DOAG conference. As you may know, this conference has very high standards in terms of turnout and top-notch speakers and it reached them once again: It was a great event!
It started with the welcome keynote where Stefan Kinnen told us that the conference attracted over 2000 attendees and more than 400 speakers from all over the world. That should make it the largest database conference in Europe, I suppose!
I went on to attend Tirthankar Lahiri who presented about the In-Memory column store:
To me, the In-Memory expressions and In-Memory external tables sounded particular useful here.
Next talk was done by Martin Widlake about Performance Tuning:
I liked his statement that in order to solve performance problems, the key skill you need is not technical in the first place, but more of a social nature: You need to thoroughly understand the problem and listen carefully. Secondly, some technical expertise is helpful, of course 🙂
Afterwards I did my own talk about Flashback in the same room to approximately 150 attendees – some less than Martin had, though:
The talk was well received, I finished my live demos in time while being able to answer some questions also – all good 🙂
Then came The Basics of Machine Learning by Heli Helskyaho (the pic I took is too bad to put it here, unfortunately) whose talk was so successful that she had to repeat it on the next day. Great job!
I went on attending Markus Michalewicz presenting about The Smartest HA Features in Oracle’s Autonomous Database:
Here I liked the new concept of “Recovery Buddies” in RAC that leads to a shorter freeze time of the Global Resource Directory if one instance fails in particular.
Then came a talk How to run a user group delivered by three (!) presidents:
Martin emphasized that you need to have (at least) one guy who is passionate about the topic and one (often another guy) who gets things organized. Apart from that, size doesn’t matter that much: You can start a user group with three persons. Kamil and Luiza told us their story about how they started the POUG user group in Poland while Stefan gave us some insights into the quite extensive DOAG internal organization.
Continued with RAC Performance Internals by Anil Nair who attracted a substantial audience in the largest room:
One takeaway here was for me that on Exadata, Oracle RAC uses ExaFusion to achieve 3 times faster block transfers over the interconnect compared to non-Exadata platforms – which is one more reason why Oracle uses Exadata as the platform for their autonomous database offers.
Then I was really shocked by the outcome of the DOAG support survey: Two thirds of the 270 customers interviewed said they are not satisfied with Oracle Support! That was even worse than two years ago when that survey reported over 50 % discontent. The room Singapur was full – but unfortunately filled with frustrated people who gave the Oracle officials present a hard time. I felt bad for them, it was a bitter moment, being for so long with Oracle myself in the past.
Went on to attend The battle between Oracle vs. PostgreSQL:
Frankly, my impression was that Daniel came up with the better arguments but Jan scored many sympathy points – nonetheless because many people wanted Postgres to win over Oracle. I think Oracle has to watch out here in order not to alienate from their customer base further. Otherwise, Postgres might continue to take away market share.
Next talk was from Paolo Kreth about Open Source Databases:
His message was that DBAs cannot ignore the usage of open source tools but have to be approachable and try to assist the internal customers with these tools. Otherwise they may just become less relevant.
Another interesting presentation was The changing role of the DBA by Valentin Leonard Tabacaru:
Especially in the light of Oracle’s new autonomous databases, his prediction is that maintenance tasks like patching will disappear while areas like data modelling, security or application tuning should become more important for DBAs.
Another very good talk was about the TimesTen In-Memory database by Doug Hood:
He showed some convincing facts to back his claim that TimesTen is the fastest In-Memory database regarding OLTP workloads while also providing fault-tolerance and scalability.
All in all, the DOAG annual conference rocked again, kudos to the DOAG members who helped organizing and running it again so smoothly!
Posted in TOI on October 12, 2018
After having installed the latest VirtualBox version, an ISO file with the latest Exasol version has to be downloaded. The machine hosting VirtualBox should have at least 16 GB RAM and 80 GB free disk space in order to run a 2+1 Cluster with 3 data nodes and one license server. I’m doing it on my Windows 10 notebook.
1.5 GB RAM is sufficient for the License Server and it needs only one disk
Insert the ISO file as a virtual CD
Make sure the License Server boots from CD first
Configure the private Network for the License Server
Configure the public network for the License Server
Now power on the virtual machine just created and configured. It should come up with this screen and you type in install
Tab to OK and press return
Tab to OK and press return
Tab to OK and press return
Choose a password. I used exasol12
Enter the public IP of the License Server. My VirtualBox Host-Only Ethernet Adapter is configured with 192.168.43.1 – therefore I use 192.168.43.10. It should also work with the VirtualBox Standard setting, in this case use 192.168.56.10. When in doubt, call ipconfig from the command shell.
Tab to OK and press return
The installation started from the last screen took me about 5 Minutes. Now type local and wait for the License Server to boot from disk. You may remove the virtual CD from it afterwards.
Do yourself a favor and pause for 5 Minutes after the machine booted from disk before you try to connect to EXAoperation. I’m using Chrome because it didn’t work well with FireFox:
The default password of the user admin is admin
Congratulation when you see the below screen! This was already the hardest part 🙂
Now add a log service to monitor the following
This helps to follow what happens under the covers for the next steps
Now the first data node is created as a VM first with 3 GB RAM
It gets two disks:
Same two network cards as the License Server and make sure it boots from network only:
Do not yet power on the new data node! Now it’s configured in EXAoperation. Go to Nodes and click Add:
You get the MAC addresses from here:
Now click on the new node to configure it further:
And so forth for the other three storage partitions so that it looks at the end like this:
Pay attention to the sizes and devices before you power on the new VM for the first data node. Then watch the log service. It should look like this:
While that is ongoing, create the VM for the second data node in the same manner as the first before. It should look like this in the end:
Click on the existing node in EXAoperation:
Change the numbers to 12 and the MAC addresses according to their values in the VirtualBox VM
Then after clicking Copy Node power on the VM. After you see it installing in the log service, do the same accordingly for the third data node. Eventually it will then look like this
Now select all nodes and execute the action set active flag
The state changes to Running Active for the three data nodes. Now click Startup Storage Service:
Now click Add Unused Disks after selecting the three data nodes:
Now click Add Volume:
Assign n11 and n12 for the new data volume with redundancy 2:
Add a new database:
Now click on the link underneath the added new database:
From the actions menu, select create
Then click startup. Change to the EXASolution main page. It should look like this:
Now you have a 2+1 Cluster running on VirtualBox – have fun with it 🙂