fritshoogland's picture

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:

dbakevlar's picture

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….

fritshoogland's picture

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:

fritshoogland's picture

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.

martin.bach's picture

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.

dbakevlar's picture

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.

martin.bach's picture

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.

pete.sharman's picture

Extending a Logical Volume Group


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 Infrastructure and RDBMS on the same device is not a concern for me. I’ve been around the Oracle database for way too many years, but my sysadmin skills leave a lot to be desired, so I did what anyone in this situation would do – I googled “resize volume linux” and followed someone else’s instructions.

fritshoogland's picture

A look into Oracle redo, part 2: the discovery of the KCRFA structure

This is the second post in a series of blogposts on Oracle database redo internals. If you landed on this blogpost without having read the first blogpost, here is a link to the first blogpost: The first blogpost contains all the versions used and a synopsis on what the purpose of this series of blogposts is.

In the first part, I showed how the principal access to the public redo strands is controlled by redo allocation latches, and showed a snippet of trace information of memory accesses of a foreground session when using the first public redo strand:

martin.bach's picture

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 post.

This is going to be a 3 part mini-series to save you having to go over 42 pages of text … In this first part I’m going to have a look at single instance Oracle. In part 2 I’ll have a look at Oracle Restart environments, and finally in part 3 I’ll finish the series by looking at a 12.2 RAC system.

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