Recently one of my customers got a complaint from their DNS administrators, our Exadata’s are doing 40.000 DNS requests per minute. We like our DNS admins so we had a look into these request and what was causing them. I started with just firing up a tcpdump on one of the bonded client interfaces on a random compute node:
Recently I was asked to look at a virtual (linux) system which needed to be moved to a new datacenter. If you want to determine if you are on VM Ware, you can use either lspci or dmidecode. A little searching on the internet revealed it’s reasonably easy to determine the version of VMWare ESX using the BIOS Information:
The other day I was wrestling with the new SharePoint 2013 App framework. I created a SharePoint 2013 SharePoint Hosted App. Besides full screen mode (which pops up when you press F5 in Visual Studio 2012), I also wanted to add an AppPart in order to make the app available on my host website. The problem I was facing is that my App Part is just an IFrame loading the main page of my App. This includes the Chrome and Navigation of the App default.aspx page. This makes my App Part look like this:
In my previous post I touched the topic of a “new” codepath (codepath means “way of utilising the operating system”) for of full segment scans. Full segment scan means scanning a segment (I use “segment” because it could be a partition of a table or index) which is visible commonly visible in an explain plan (but not restricted to) as the rowsources “TABLE ACCESS FULL”, “FAST FULL INDEX SCAN” and “BITMAP FULL SCAN”.
I was bored during the holidays and decided to brush up on my python skills. I have created a small python program to list the topology of a Gluster volume, called lsgvt (LiSt Gluster Volume Topology). It’s at github. To give you a small example of it’s output:
Recently I was discussing some IO related waits with some friends. The wait I was discussing was ‘kfk: async disk IO’. This wait was always visible in Oracle version 18.104.22.168 and seems to be gone in version 22.214.171.124 and above. Here is the result of some investigation into that.
I guess the first question which comes to mind when reading this title is ‘Why’? For a database, but I guess for any IO depended application, we want IO’s to be faster, not throttle them, alias make them slower. Well, the ‘why’ is: if you want to investigate IO’s, you sometimes want them to slow down, so it’s easier to see them. Also, (not so) recent improvements in the Oracle database made great progress in being able to use the available bandwidth by doing IO in parallel, which could strip away much of the ability to see them in Oracle’s popular SQL trace.
In Windows 2012 it’s possible to add a source path to the Add-WindowsFeature and Install-WindowsFeature cmdlet. This may be necessary when the source files needed to install a feature are not locally cached on your server. In the example below, I tried to install NET-Non-HTTP-Activ, required for my SQL/SCCM installation
Met toast notificaties kan je de aandacht van de gebruiker krijgt terwijl je app niet draait. Wat er zo uit kan zien: