A look into oracle redo, part 11: log writer worker processes

Starting from Oracle 12, in a default configured database, there are more log writer processes than the well known ‘LGWR’ process itself, which are the ‘LGnn’ processes:

$ ps -ef | grep test | grep lg
oracle   18048     1  0 12:50 ?        00:00:13 ora_lgwr_test
oracle   18052     1  0 12:50 ?        00:00:06 ora_lg00_test
oracle   18056     1  0 12:50 ?        00:00:00 ora_lg01_test

These are the log writer worker processes, for which the minimal amount is equal to the amount public (more...)

Ubuntu: Upgrade from 17.10 to 18.04


Last week ubuntu release 18.10 and i upgraded my notebook to the latest version.
I was running 17.10 with wayland:

$ lsb_release  -a
No LSB modules are available.
Distributor ID:    Ubuntu
Description:    Ubuntu 17.10
Release:    17.10
Codename:    artful

# do-release-upgrade -d
Neue Veröffentlichungen von Ubuntu werden gesucht
Holen:1 Signatur der Aktualisierungsanwendung [819 B]                                                                                                                                                                                  
Holen:2 Aktualisierungsanwendung [1.257 kB]                                                                                                                                                                                            
Es wurden 1.258 kB in 0 s geholt (0 B/s)                                                                                                                                                                                               
»bionic. (more...)

Fedora User Manager

As one of my students pointed out, Fedora doesn’t install a GUI user management tool installed by default. That’s true. It’s easy to install. You can install it as the root user, like:

yum install -y system-config-users

It should generate a screen console output like this when successfully installed:

Loaded plugins: langpacks, refresh-packagekit
http://yum.postgresql.org/9.3/fedora/fedora-20-x86_64/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
Trying other mirror.
Resolving Dependencies
--> Running transaction check
 (more...)

Oracle Linux 7 Update 5 is out: time to create a new Vagrant Base Box

It's been busy, so unfortunately it's already been almost two weeks I wrote my introductory story on Vagrant. Today I happen to have an afternoon off, and I noticed that Oracle Linux 7 Update 5 is out. I based my first boxes on 7.4, so nice moment to start with creating a new Base Box.

De essentials on creating a Vagrant base box can be read here. But I'm going to guide you trough (more...)

Fedora Install unixODBC

Encountered a problem while running the RODBC library from the R prompt as the root user, as follows:

> install.packages('RODBC')

It failed with the following library dependency:

checking for unistd.h... yes
checking sql.h usability... no
checking sql.h presence... no
checking for sql.h... no
checking sqlext.h usability... no
checking sqlext.h presence... no
checking for sqlext.h... no
configure: error: "ODBC headers sql.h and sqlext.h not found"
ERROR:  (more...)

A look into oracle redo: index and overview

I gotten some requests to provide an overview of the redo series of blogposts I am currently running. Here it is:

https://fritshoogland.wordpress.com/2018/01/29/a-look-into-oracle-redo-part-1-redo-allocation-latches/
https://fritshoogland.wordpress.com/2018/02/05/a-look-into-oracle-redo-part-2-the-discovery-of-the-kcrfa-structure/
https://fritshoogland.wordpress.com/2018/02/12/a-look-into-oracle-redo-part-3-the-log-writer-work-cycle-overview/
https://fritshoogland.wordpress.com/2018/02/20/a-look-into-into-oracle-redo-part-4-the-log-writer-null-write/
https://fritshoogland.wordpress.com/2018/02/27/a-look-into-oracle-redo-part-5-the-log-writer-writing/
https://fritshoogland.wordpress.com/2018/03/05/a-look-into-oracle-redo-part-6-oracle-post-wait-commit-and-the-on-disk-scn/
https://fritshoogland.wordpress.com/2018/03/19/a-look-into-oracle-redo-part-7-adaptive-log-file-sync/
https://fritshoogland.wordpress.com/2018/03/26/a-look-into-oracle-redo-part-8-generate-redo/
https://fritshoogland.wordpress.com/2018/04/03/a-look-into-oracle-redo-part-9-commit/
https://fritshoogland.wordpress.com/2018/04/09/a-look-into-oracle-redo-part-9a-commit-concurrency-considerations/
https://fritshoogland.wordpress.com/2018/04/16/a-look-into-oracle-redo-part-10-commit_wait-and-commit_logging/

New option for configuring multipathing in Oracle Linux 7

Teaching is and remains the best way for picking up new things :) While updating notes for a class I came across an interesting change in the way the device-mapper multipath works in Oracle Linux 7.4.

In the past, everyone including me used scsi_id to get the WWID of a LUN for use with dm-multipath. This is still the way Oracle documents it for Oracle Linux 7.

The utility was specified as an argument (more...)

A look into oracle redo, part 9a: commit – concurrency considerations

During the investigations of my previous blogpost about what happens during a commit and when the data becomes available, I used breaks in gdb (GNU debugger) at various places of the execution of an insert and a commit to see what is visible for other sessions during the various stages of execution of the commit.

However, I did find something else, which is very logical, but is easily overlooked: at certain moments access to (more...)

Ubuntu: unmet dependencies gparted (libparted-fs-resize0 (>= 3.1))

After a new ubuntu installation i got the following error:
root@pc:/etc/apt/sources.list.d# apt install   gparted
Paketlisten werden gelesen... Fertig
Abhängigkeitsbaum wird aufgebaut.   
Statusinformationen werden eingelesen.... Fertig
Einige Pakete konnten nicht installiert werden. Das kann bedeuten, dass
Sie eine unmögliche Situation angefordert haben oder, wenn Sie die
Unstable-Distribution verwenden, dass einige erforderliche Pakete noch
nicht erstellt wurden oder Incoming noch nicht verlassen haben.
Die folgenden Informationen helfen Ihnen vielleicht, die Situation zu lösen:
(more...)

A look into oracle redo, part 9: commit

The previous blogpost talked about a simple insert, this blogpost investigates what happens when the DML is committed. Of course this is done with regular commit settings, which means means they are not touched, which means commit_logging is set to immediate and commit_wait is set to wait as far as I know. The documentation says there is no default value, and the settings are empty in all parameter views. In my humble opinion, if you (more...)

A look into oracle redo, part 8: generate redo

This blogpost looks at the very start of oracle redo: the generation of it. In order to do that, I start off with a very simple table, and look at the redo generation part. I guess the regular readers of this blogpost series understand that redo generation is closely connected with making changes made to blocks. This post therefore is not only about redo generation, but also about how the technical implementation of block changes.

(more...)

Stop password for user accounts expiring on Exadata

Depending on how the Oracle Exadata Machine was setup, the password for user accounts can expire thus requiring the password to be changed.

This has the knock on effect of the crontab not accessible and more importantly jobs do not run:

[oracle@v1ex1dbadm01 ~]$ crontab -l

Authentication token is no longer valid; new one required
You (oracle) are not allowed to access to (crontab) because of pam configuration.
[oracle@v1ex1dbadm01 ~]$

You can (more...)

Method R Profiler on x86_64 Linux with HiDPI


For a new installed Linux Laptop I tried to install Method R Profiler (and Tools).
But it was not as smooth as expected.

mrprop_wrapper failed with

/opt/mrprof/mrprof_wrapper: line 45: /opt/mrprof-7.1.1.3-linux32/bin/mrprof.exe: No such file or directory
But the file is there, and it's executable.
So the Error is slightly misleading.
Also strace showed a similar error:
execve("/opt/mrprof-7.1.1.3-linux32/bin/mrprof.exe", ["/opt/mrprof-7.1.1.3-linux32/bin/"...], [/* 62 vars */]) = -1  (more...)

Where in the World Has Goth Geek Girl Been

I’m on track to fly home tomorrow, March 11th after nine days and three events.  I’m pretty exhausted and just ready to go home and catch up on some sleep…:)

I started out last weekend in Victoria BC and was thrilled to be on this emerald island of the Pacific Northwest.  British Columbia is gorgeous as it is, but Victoria is a special place that quickly became one of my favorite places in (more...)

Playing with Google Authenticator and Oracle Cloud – Securing SSH to Oracle account with two factor authentication

The Requirement Increase security when connecting via SSH to the Oracle OS account at Oracle Cloud by implementing two factor authentication (TFA or 2FA). The Environment Oracle Cloud Instance OS: Oracle Linux 6.9 The Implementation For this exercise we will

A look into Oracle redo, part 5: the log writer writing

| Feb 27, 2018

This the the fifth blog in a series of blogposts about Oracle database redo. The previous blog looked into the ‘null write’ (kcrfw_do_null_write actually) function inside kcrfw_redo_write_driver, which does housekeeping like updating SCNs and posting processes if needed, this blog looks into what happens when the log writer is actually posted by a process or if public redo strand buffers have been written into. In part 3 of this blog series (the log writer working (more…)

You may still need gcc when patching Oracle Database 12.2

I have previously written about changes in the Oracle 12.2 preinstall RPM and how gcc is no longer part of the dependencies list. As was pointed out to me, this shouldn’t be necessary anymore, according to the 12.2 Linux Database Installation Guide. Check the blue note for a statement indicating that gcc and gcc-c++ aren’t needed for Grid Infrastructure, nor for the RDBMS software.

I have applied patch 27100009 (January 2018 Release Update (more...)

OSWatcher, Tracefile Analyzer, and Oracle Restart 12.2

You are about to read the second part of this mini-series on TFA and Oracle 12.2. In the previous article I wrote about TFA and Oracle 12.2 single instance. In this short article I am going to have a look at TFA in a 12.2 Oracle Restart environment before rounding it up with an investigation into a full-blown RAC installation in part 3.

Summarising the first part I can only say that (more...)

Extending a Logical Volume Group

Introduction

Today I ran into the situation where I needed to extend a logical volume group so I could complete an installation. I’d already installed the Grid Infrastructure, but there wasn’t enough room remaining to install the Oracle kernel on the same device. This is for a test environment which was being built on a VM that had just been created, and performance is not the issue we’re looking at here, so installing the Grid (more...)

OSWatcher, Tracefile Analyzer, and Oracle 12.2 single instance

I have previously written about TFA, OSWatcher et all for Oracle 12.1. Since then, a lot of things have happened and I had an update for 12.2 on my to-do list for far too long. Experience teaches me that references to support notes and official documentation get out of date rather quickly, so as always, if you find anything that changed please let me know via the comments section and I’ll update the (more...)