For this (more...)
For this (more...)
This is just another short post about one of the little things worth knowing. Assume you are on 18.104.22.168 for example and you want to know if parallel_degree_limit reliably keeps the degree of parallelism at bay, for all sessions and queries across the board. After all, every machine has finite CPU (and other) resources that shouldn’t be exhausted. Setting parallel_degree_limit of course only has an effect if you set parallel_degree_policy to limited, auto (more...)
If you’re reading this post, you most likely are trying to run the Oracle Database 11g or 12c
runInstaller program, and it’s failing a critical dependency check and displaying an error like the one below. If so, choose
n because if you choose
y it won’t launch the Oracle Installer.
Starting Oracle Universal Installer... Checking Temp space: must be greater than 500 MB. Actual 30824 MB Passed Checking swap space: must be greater than (more...)
In a previous article called ‘memory allocation on startup’ I touched on the subject of NUMA; Non Uniform Memory Access. This article is about how to configure NUMA, how to look into NUMA usage and a real life case of NUMA optimisation using in-memory parallel execution.
At this point in time (start of the summer of 2016) we see that the CPU speed competition has stagnated and settled at somewhere below maximally 4 gigahertz, and (more...)
Previous work and motivations
Tools for dynamic tracing are very useful for troubleshooting and internals investigations of Oracle workloads. Dynamic tracing probes on the OS/kernel, can be used to measure the details for I/O latency for example. Moreover probes on the Oracle (more...)
In my last post I wrote down some notes about my experience while experimenting with the ZFSSA simulator. A simulator is a great way to get familiar with the user interface and general usability of a product. What I wanted to find out using the ZFSSA simulator was the answer to the question: “what happens to a clone of a database when I roll the master copy forward?”
In the first part of the (more...)
Installing any Oracle database is tedious, but the installing the pre-requisites can be tedious. This post tries to simplify the process by creating a single
prereq.sh file for all the pre-requisite libraries. The file should contain the following:
yum install -y binutils \ compat-libstdc++-33 \ compat-libstdc++-33.i686 \ gcc \ gcc-c++ \ glibc \ glibc.i686 \ glibc-devel \ glibc-devel.i686 \ ksh \ libgcc \ libgcc.i686 \ libstdc++ \ libstdc++. (more...)
This is a small blogpost on using ‘perf’. I got an error message when I tried to run ‘perf top’ systemwide:
# perf top Too many events are opened. Try again after reducing the number of events
What actually is the case here, is actually described in the perf wiki:
Open file limits
The design of the perf_event kernel interface which is used by the perf tool, is such that it uses one file (more...)
This post shows you how to add the menu option and GUI to set users and groups. It’s quite a bit easier than mastering all the command-line syntax. It makes setting up the required user and group accounts for an Oracle Enterprise or MySQL database solution much easier.
You add the utility by calling the yum (Yellowdog Updater, Modified) utility like this:
yum installed -y system-config_users
You should see the following:
Loaded plugins: langpacks Usage: (more...)
Recently I have been presenting on what running on a large intel based NUMA system looks like (OTN EMEA tour in Düsseldorf and Milan, and I will be presenting about this at the Dutch AMIS 25th anniversary event in june). The investigation of this presentation is done on a SGI UV 300 machine with 24 terabyte of memory, 32 sockets (=NUMA nodes), 480 core’s and 960 threads.
Recently I have been given access to a (more...)
Occasionally, my students loose their network connection when copying their virtual machines. This article shows you how to rebuild your Internet connection.
The first step requires you to identify the port number on your host operating system, which is typically Windows OS or Mac OS X. You can find that by running the following search from a Mac OS X Terminal session or Windows OS Command session.
If you’re on the Mac OS X, you (more...)
The scripts help in installing the software and creating the Repository. I started to create a script for creating the domain, but haven't it working yet. A good starting poing would be this blog of Edwin Biemond for the (more...)
Recently I have been asked how the Copy-on-Write cloning works on the ZFS Storage Appliance. More specifically, the question was about the “master” copy: did it have to be static or could it be rolled forward? What better than a test to work out how it works. Unfortunately I don’t have an actual system available to me at home so I had to revert to the simulator, hoping that it represents the real appliance accurately.
Prompted by comments made by readers about my posts describing how to add a second SCAN in 12c Release 1 and problems regarding the listener_networks parameter I thought it was time to revisit the situation. I’m still running Oracle Linux 7.1/UEK3 (although that should not matter) but upgraded to 22.214.171.124.5. This is the release that is reportedly showing the odd behaviour. I don’t recall my exact version when I wrote (more...)
I’ve updated my install cookbooks page to include a new cookbook for installation of Oracle 126.96.36.199 Real Application Clusters on Oracle Linux 6.7.
This is also the first one I’ve published since I left the employment of Violin Memory to work for Kaminario, so this install uses a Kaminario K2 All Flash Array. However, it applies very well to any Oracle RAC installation which uses relatively capable storage.
SystemTap and dynamic tracing tools in general give administrators great control on their systems with the relatively little additional effort to learn the new tools. In this post you will see of how SystemTap that can be used to modify data on the fly at runtime. The outcome is a form of "live patching". Examples are provided on how to apply these ideas to Oracle SQL parsing functionality. This type of "guru mode" use (more...)
The Oracle Service Bus has built in features to poll an IMAP of POP3 mail account. There are loads of excellent blog posts that exactly describe how to do it. However, when the mail server happens to be a Microsoft Exchange server, things become shady. Exchange’s IMAP implementation tends to be not really that compatible, and the server log will fill up with stacktraces such as:
javax.mail.MessagingException: Connect failed; nested exception is: java. (more...)
I was setting up disk devices for ASM in Oracle Linux 7. I knew things have changed between Oracle Linux 6 and Oracle Linux 7, but only just a little bit.
First of all, let’s take a look at the current disk usage. To see what disk devices are visible and how they are used, use lsblk:
# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT fd0 2:0 1 4K 0 disk sda 8:0 0 (more...)
The intention of this blogpost is to show the Oracle wait time granularity and the Oracle database time measurement granularity. One of the reasons for doing this, is the Oracle database switched from using the function gettimeofday() up to version 11.2 to clock_gettime() to measure time.
This switch is understandable, as gettimeofday() is a best guess of the kernel of the wall clock time, while clock_gettime(CLOCK_MONOTONIC,…) is an monotonic increasing timer, which means it (more...)
This is the second blogpost on using PL/SQL inside SQL. If you landed on this page and have not read the first part, click this link and read that first. I gotten some reactions on the first article, of which one was: how does this look like with ‘pragma udf’ in the function?
Pragma udf is a way to speed up using PL/SQL functions in (user defined function), starting from version 12. If you want (more...)