About Long Fat Networks and TCP tuning


Recently I came about a data communications subject that was pretty unknown to me, known as the Bandwidth-delay product. Knowledge about this can help you to recognize certain network issues and ways to resolve them. It is all about two Linux hosts, a source and a destination host, communicating with each other over a high capacity network link. The question is how can you, given this scenario, reach maximum throughput over the network?


The first step is to determine the Bandwidth-delay product for this network. Bandwidth-delay product (BDP) is defined as the product of a data link’s capacity (in bits per second) and its round-trip delay time (in seconds). The result, the amount of data (in bits or bytes), is the maximum amount of data on the network at any given time, that is data that has been transmitted but not yet acknowledged.
Why is this important? The TCP protocol is designed for reliable transmission of data, acknowledgements are an essential part of the protocol. A high BDP value has impact on the efficiency of TCP, because the protocol can only achieve optimum throughput if a sender sends a sufficiently large quantity of data before being required to stop and wait until a confirming message (acknowledgement) is received from the receiver, acknowledging successful receipt of that data.

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Check_MK and vSphere – vCenter Server


This post is the third part in a series about Check_MK and vSphere. In the second part, I showed you the options for monitoring an ESXi host without using vCenter Server. In this post we will explore the options for monitoring a vCenter Server on Windows and also the vCenter Server Appliance (VCSA).

vCenter Server Windows

For this POC we have a vCenter Server 6.0 U2 (build 3634793) on a Windows Server 2012 R2. As this is a normal Windows server, I installed the Check_MK agent for Windows and added the host to Check_MK. For the property Agent type, select “Check_MK Agent (Server)”.

2016-08-21_01Figure 1

By default the Check_MK Windows Agents presents – without further tweaking – a lot of information; CPU and Memory utilization, Disk I/O, status of the filesystems, status of the Network interfaces and many more.

Now it’s time to reveal the vSphere options. We follow the same procedure as we did for the ESXi host. In the WATO configuration go to Host & Service Parameters \ Datasource Programs and select Check state of VMware ESX via vSphere. Now create a second rule for the vCenter Server, start with providing a descriptive name.

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Check_MK and vSphere – ESXi


This post is the second part in a series about Check_MK monitor and vSphere. In the first part Check_MK was introduced and some basic Installation and Configuration was explained.

According to the documentation, for monitoring VMware ESXi and vCenter Server, Check_MK has implemented a plugin that uses the vSphere API for retrieving information. This plugin is much more efficient than versions based on the Perl API.

So let’s start and see what can be revealed. To get a clear understanding of the various options, I will perform a step-by-step configuration instead of ticking all options at once.

The first step is to go into WATO and add an ESXi host. Under WATO, choose, Hosts and New Host.

2016-08-10-01Figure 1

You must at least enter the Hostname and an IP address, the Alias is optional. Under Agent Type place a tick and select “No Agent”.

At this time, the result is not very exciting; the ESXi host will be pinged.

2016-08-10-02Figure 2

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Check_MK and vSphere – Introduction



Infrastructure monitoring is essential to carry out proper System Administration. Infrastructure consists of many components, starting with the basics such as server hardware, network components, storage, uninterruptible power supplies, backup equipment, but also environmental factors such as temperature and air humidity in server rooms. Apart from understanding the hardware, software is the next layer. Starting with Operating Systems; monitoring of resources such as CPU, memory, storage, network, state of essential services etc. Next level is applications and chained applications. Examples, monitoring mail queues of a mail server or databases from a SQL Server and so on.

Today, many monitoring products are available; many of these are tailored to special purposes and don’t cover all aspects of an Infrastructure.
I have noticed in recent years that many organizations are searching for a single product that can be used for monitoring as many components. Because nowadays most organizations run workloads on virtualized infrastructure, this means an extra challenge for the monitoring software.

Years ago, when I worked as a Sysadmin and virtualization was in a very early stage, my favorite monitoring software was a combination of the following products Nagios, Cacti and an advanced Syslog server.
Nagios has its origins as an Open Source product. Due to its open source nature, there are many products derived from Nagios, examples; OP5, Opsview, Groundwork, Check_MK and many more.

Some time ago Check_MK caught my attention, mainly because of its versatility and its ability to monitor diverse infrastructure including VMware vSphere.

In this and subsequent blog posts, I will investigate the potential of Check_MK, in particular the possibilities to monitor vSphere and other VMware products. Since there are already many excellent articles written about the installation and configuration I will not repeat these steps. Where needed, I will include references to articles that I used to build my Proof-of-Concept and issues that I encountered.

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vOPS Server Explorer 6.3 release


Today, Dell released the latest version of the vOPS Server Explorer, version 6.3 to be more precise. Last year, Dell acquired vKernel and with that, its flagship product vOPS Server Standard.

vOPS Server Explorer is a freeware suite, this version adds two new utilities, Storage Explorer and Change Explorer, plus adds improvements to Environment Explorer. So there are now a total of five utilities in the vOPS free VM tool.

  • Environment Explorer
  • vScope Explorer
  • Search VM Explorer
  • Storage Explorer
  • Change Explorer

vOPS Server Explorer uses the same analytics and advisory engine from the paid vOPS Server Standard product, all five of these utilities provide virtual administrators with a rapid assessment of the state of their environment.

vOPS Explorer-01

Figure 1 – Storage Explorer (provided by Dell)

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VMware vCenter Operations Standard – Part 2: First look


In my previous post about vCenter Operations Standard (from now on vCOPS), I showed you how to install vCOPS and do some initial configuration.

After completion it is time to discover the features of this tool. My first action was to configure SMTP. As a regular user of tools like Nagios, I like to receive notifications in case of trouble. Unfortunately, after filling in the required fields, there is no button to Test your email configuration!

So let us go back to vCOPS, the first thing to notice, is the complete different look and feel of what we are used to in vCenter and other Solutions and Applications. VMware Update Manager and VMware Data Recovery, seamlessly integrate in vCenter.

vCOPS can completely run in a browser, that gives the opportunity to easily switch between vCOPS and vCenter

After my first tour, I was a bit confused and lost. So I returned to the “Installation and Administration Guide” which contains a section about the main concepts of vCOPS. So I learned about Workloads, Health, Capacity, attributes, metrics, dynamic- and hard thresholds, key performance indicators and probable causes, but still fuzzy…

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VMware vCenter Operations Standard- Part I: Install and Configure


Last week the launch of the VMware vSphere Client for iPad received a lot of attention. But VMware also released another interesting product: vCenter Operations.

According to VMware “vCenter Operations Standard is for vCenter administrators who want to better understand the performance of their virtual infrastructure, and to diagnose and correct performance problems easily and quickly.”

A comprehensive overview about the product and its origin can be found here on Virtualization.info.

vCenter Operations provides performance, capacity and configuration analytics for management of highly virtual infrastructures and cloud infrastructures. It does so by analyzing and correlating data across the monitored IT infrastructure in a pretty unique way: for each tracked resource, it can identify the normal behavior of every metric (which implies a dynamic adjustment of thresholds) and then automatically recognize an anomaly.

So it seems VMware is entering a market with a lot of competitors. Not only the big boys, but also with specialists like VKernel and they do not seem to be very happy, according to this post.

Enough said, let’s start. At this time vCenter Operations is available here and comes in two flavors:

  • Standard, the actual VMware vCenter Operations Standard 1.0;
  • Advanced, as Standard plus VMware vCenter CapacityIQ 1.5.1.

After downloading, you also receive a license which entitles you to play around with the products for 60 days. It is also a good idea to download the documentation, most important document is the “VMware vCenter Operations Standard Installation and Administration Guide”.

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