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A look into oracle redo, part 7: adaptive log file sync

This is the seventh part of a blog series about oracle redo.

Adaptive log file sync is a feature that probably came with Oracle version 11.2. Probably means I looked at the undocumented parameters of Oracle version 11.1 and do not see any of the ‘_adaptive_log_file_sync*’ parameters. It was actually turned off by default with versions and, and was turned on by default since version

Linux timing and scheduling granularity

During investigating how Oracle works with regards to waiting, I discovered an oddity. I was researching for my redo blog posts, and found that in a certain case, Oracle uses the ‘nanosleep’ system call. As the name of this system call suggests, this call allows you to let a process sleep with nanosecond precision.

The oddity that I found, was the following:

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 the world.

A look into Oracle redo, part 6: oracle post-wait commit and the on disk SCN

This is the sixth part in a blog series about Oracle database redo. The previous posts provided information about the log writer writing, this post is about the process that is waiting after issuing commit for the log writer to write it’s redo from the public redo strand. When the database is using post/wait for process commits, the committing process follows the following (simplified) procedure:

Can You DIG It?

As I dig deeper into Linux for the SQL Server DBAs and for Oracle HotSos, I’m digging into DIG.  Yeah, I went there with that first sentence….

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

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 cycle) it can be seen that when a session posts the log writer, it returns from the semaphore related functions, and calls ‘kcrfw_redo_write_driver’ directly, which otherwise is called inside ksbcti.

Inside the kcrfw_redo_write_driver function, the first thing of interest is executed only when the logwriter is posted, and the kcrfw_redo_write_driver function is called directly after returning from ksarcv and ksl_exit_main_loop_wait:

A look into into Oracle redo, part 4: the log writer null write

This is the fourth blogpost on a series of blogposts about how the Oracle database handles redo. The previous blogpost talked about the work cycle of the log writer: This posts is looking into the execution of the kcrfw_redo_write_driver function executed in the ksbcti.

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 on my 2 node RAC system in the lab, and found out that this is partially true :) You may or may not encounter this issue in your environment, see below.

Docker and Windows 10 1709 Patch, The End

So if you read my last post on my challenges with Docker containers running on Windows 10 after the 1709 patch, I thought I was close to solving it once I was granted the admin password to disable and uninstall Sophos Endpoint.

Once I uninstalled Sophos, I noted I ended up with a different line number error.  The question was, has the problem shifted from Sophos to a new issue or is it more complex than just the one application?  We’d already seen that it was complicated, including the Hyper-V with the 1709 patch that was part of the problem.

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 I am very happy that we now get TFA as part of the standard installation. Running it in daemon mode provides some great insights, and even if you did not upgrade the installation to “MOS-TFA”, you have a very fine tool for Oracle troubleshooting at your disposal.

Summary of the environment

My environment is largely the same as last time, except the machine name changed to server4 and I have additional storage for use with ASM.