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티베로 – The AWR-like “Tibero Performance Repository”

By Franck Pachot

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In a previous post I introduced Tibero as The most compatible alternative to Oracle Database. Compatibility is one thing but one day you will want to compare the performance. I’ll not do any benchmark here but show you how you we can look at the performance with TPR – the Tibero Performance Repository – as an equivalent of AWR – the Oracle Automatic Workload Repository. And, as I needed to run some workload, I attempted to run something that has been written with Oracle Database in mind: the Kevin Closson SLOB – Silly Little Oracle Benchmark. The challenge is to make it run on Tibero and get a TPR report.

SLOB

I’ve downloaded SLOB from:

SLOB Chewed Up All My File System Space and Spit It Out. But, Why?

This is a quick blog post in response to a recent interaction with a SLOB user. The user reached out to me to lament that all her file system space was consumed as the result of a SLOB execution (runit.sh). I reminded her that runit.sh will alert to possible derelict mpstat/iostat/vmstat processes from an aborted SLOB test. If these processes exist they will be spooling their output to unlinked files.

The following screen shot shows what to expect if a SLOB test detects potential “deadwood” processes. If you see this sort of output from runit.sh, it’s best to investigate whether in fact they remain from an aborted test or whether there are other users on the system that left these processes behind.

 

Which Bitnami service to choose in the Oracle Cloud Infrastructure?

By Franck Pachot

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In the Oracle Cloud PaaS you have a marketplace where you can choose your service. Some are packaged from Bitnami and available on multiple OS. My first idea is that in PaaS you do not care about the OS. But Oracle Cloud has this very nice feature where you still have full access to the OS, as root, even in PaaS. Then, you choose the Linux distribution of your preference. Except if performance is different. They run on different Linux kernels. Is Oracle Linux Unbreakable Kernel more efficient?

Postgres, the fsync() issue, and ‘pgio’ (the SLOB method for PostgreSQL)

By Franck Pachot

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That’s a long blog post title, which is actually just a good pretext to play with Kevin Closson SLOB method for PostgreSQL: pgio
I use the beta version of pgio here. If you want to read more about it, you can start on https://kevinclosson.net/2018/05/22/sneak-preview-of-pgio-the-slob-method-for-postgressql-part-i-the-beta-pgio-readme-file/. If you are used to the SLOB for Oracle (https://kevinclosson.net/slob/) you will quickly understand the ‘why’ and ‘how’ of pgio.

Spectre and Meltdown on Oracle Public Cloud UEK – LIO

In the last post I published the strange results I had when testing physical I/O with the latest Spectre and Meltdown patches. There is the logical I/O with SLOB cached reads.

Spectre/Meltdown on Oracle Public Cloud UEK – PIO

The Spectre and Meltdown is now in the latest Oracle UEK kernel, after updating it with ‘yum update':

[opc@PTI ~]$ rpm -q --changelog kernel-uek
| awk '/CVE-2017-5715|CVE-2017-5753|CVE-2017-5754/{print $NF}' | sort | uniq -c
43 {CVE-2017-5715}
16 {CVE-2017-5753}
71 {CVE-2017-5754}

As I did on the previous post on AWS, I’ve run quick tests on the Oracle Public Cloud.

Physical reads

I’ve run some SLOB I/O reads with the patches, as well sit KPTI disabled, and with KPTI, IBRS and IBPB disabled.

And I was quite surprised by the result:

Spectre and Meltdown, Oracle Database, AWS, SLOB

Last year, I measured the CPU performance for an Oracle Database on several types of AWS instances. Just by curiosity, I’ve run the same test (SLOB cached reads) now that Amazon has applied all Spectre and Meltdown mitigation patches.

I must admit that I wanted to test this on the Oracle Cloud first. I’ve updated a IaaS instance to the latest kernel but the Oracle Unbreakable Enterprise Kernel does not include the Meltdown fix yet, and booting on the Red Hat Compatible Kernel quickly goes to a kernel panic not finding the root LVM.

Google Cloud Platform instances and Oracle Database

When it comes to choose a cloud instance to run Oracle Database, you want to be able to run your workload on the minimum CPU cores. This is why in a previous post I measured how many logical reads per seconds can be achieved with a SLOB workload, on AWS which is often the first considered, and will probably do it on Azure in the future. I did the same on the Oracle Cloud which is the only one where Oracle make it easy to run an license the Oracle Database.

SLOB 2.3 Data Loading Failed? Here’s a Quick Diagnosis Tip.

The upcoming SLOB 2.4 release will bring improved data loading error handling. While still using SLOB 2.3, users can suffer data loading failures that may appear–on the surface–to be difficult to diagnose.

Before I continue, I should point out that the most common data loading failure with SLOB in pre-2.4 releases is the concurrent data loading phase suffering lack of sort space in TEMP. To that end, here is an example of a SLOB 2.3 data loading failure due to shortage of TEMP space. Please notice the grep command (in Figure 2 below) one should use to begin diagnosis of any SLOB data loading failure:

Is SLOB AWR Generation Really, Really, Really Slow on Oracle Database 11.2.0.4? Yes, Unless…

If you are testing SLOB against 11.2.0.4 and find that the AWR report generation phase of runit.sh is taking an inordinate amount of time (e.g., more than 10 seconds) then please be aware that, in the SLOB/awr subdirectory, there is a remedy script rightly called 11204-awr-stall-fix.sql.

Simply execute this script when connected to the instance with sysdba privilege and the problem will be solved.