jump to navigation

The ESX Admins Group and how does the ESXi host know about it July 31, 2012

Posted by vbry21 in VMware blogs.
1 comment so far

On the VMware Install, Configure and Manage course and Fast Track course we talk about Role and we discuss the importance for delegated administration, In version 5 we have the ability to add our ESXi hosts to Active Directory.

The advantage of this is as follows.

We can allow the system administrators to login to the vSphere Client, the vMA and the Direct Console User Interface with an Active Directory account, this then removes the need to divulge the root user password.

One of the statements made on the courses is as follows.

Users who are in the Active Directory Group ESX Admins are automatically assigned to the Administrator Role.

But how does the ESXi hosts know about this group? Well it’s configurable.

Just click the graphic to show in full screen

As can be seen in the graphic,from the vSphere Client, select Hosts and Clusters view, then highlight the host, go to configuration, software and advanced, then select Config > HostAgent > Plugins > Hostsvc and the first option is to specify the AD group used for administration.

The second option, controls whether the group is used.


Supported databases for the linux VMware vCenter App July 30, 2012

Posted by vbry21 in VMware blogs.
add a comment

I was teaching an ICM 5 course today and one of the things the course states is that the new vCenter App (Linux vCenter Server), supports Oracle and IBM DB2 as external databases.

That’s not the case, but in defence the course is written pre release and any good instructor can point out the descrepancies.

We then continue through, I demonstrate the installation and we find no external IBM DB2 database.

The other thing mentioned in the course is that the embedded database is IBM DB2, it was with 5.0 but now with 5.0.1 the embedded database is PostgreSQL.

Below is an extract from the Admin guide for vCenter Virtual App

As an alternative to installing vCenter Server on a Windows machine, you can download the VMware vCenter Server Appliance. The vCenter Server Appliance is a preconfigured Linux-based virtual machine optimized for running vCenter Server and associated services.

The vCenter Server Appliance has the default user name root and password vmware.

Microsoft SQL Server and IBM DB2 are not supported for the vCenter Server Appliance.


Version 5.0.1 of the vCenter Server Appliance uses PostgreSQL for the embedded database instead of IBM DB2, which was used in vCenter Server Appliance 5.0.

The vCenter Server Appliance does not support Linked Mode configuration. The vCenter Server Appliance does not support IPv6.


The embedded database is not configured to manage an inventory that contains more than 5 hosts and 50 virtual machines. If you use the embedded database with the vCenter Server Appliance, exceeding these limits can cause numerous problems, including causing vCenter Server to stop responding.


Upgrading VMFS 3 to VMFS 5 July 25, 2012

Posted by vbry21 in VMware blogs.
add a comment

I had an interesting question about upgrading from vSphere Version 4 to Version 5.

Once the upgrade is finished the VMFS datastores will be VMFS version 3? The ESXi 5.0 operating system uses VMFS 5.0? Can I do an in place upgrade.

My answer was yes, select your datastore.

In Hosts and Clusters view

Select the Host > Configuration Tab > select the VMFS 3 datastore > click upgrade to VMFS 5 in the GUI.

Remember that VMFS 5 is only supported on hosts running ESXi 5.0 and later.

Also the VMs running on the datastore do not have to be moved or powered off.

But let’s say for example that the block size was 8MB on the original VMFS 3, which means it will be 8MB on the VMFS 5 datastore. The delegate wanted 1 MB blocks. With VMware there’s always a workaround.

This was going to cause an issue, however on analysis we found we had spare capacity across the datastores, so instead we decided on a storage vMotion of VMs to a different datastore, we then deleted and recreated the datastores as VMFS 5 1MB block and repeated until all datastores were now version 5.



VMware alarms, there;s two types, read on July 13, 2012

Posted by vbry21 in VMware blogs.
add a comment

I was asked a question about alarms in VMware, the question was.

“What is the difference between, event based alarms and condition based alarms?”

Here goes.

You configure alarm triggers to generate warnings and alerts when the specified triggers are met. Alarms have two types of triggers: condition, or state, triggers, and event triggers.

Condition or state triggers – Monitor the current condition or state of virtual machines, hosts, and datastores. Conditions or states include power states, connection states, and performance metrics such as CPU and disk usage.

Event triggers – Monitor events that occur in response to operations occurring with a managed object in the inventory or the vCenter Server system itself. For example, an event is recorded each time a virtual machine (which is a managed object) is cloned, created, deleted, deployed, and migrated.

On our Vsphere 5 ICM or Fastrack, there’s a lab that allows the delegates to create alarms.

The first alarm is a condition based alarm, we monitor for CPU usage within the VM, when the CPU utilisation exceeds the trigger value the alarm triggers and the VM suspends.

We then create a second alarm, this time an event based alarm, and the event we monitor for is a suspended VM, with this alarm we get an Alert to tell us the alarm has triggered.

To see a demo click this link

Memory overcommitment and techniques to allow this June 13, 2012

Posted by vbry21 in VMware blogs.
Tags: ,
add a comment

Memory Reclamation Techniques in ESXi

I’ve mentioned the four main memory reclamation techniques mentioned in the Resource Management Guide, but there’s also Host cache as well. The purpose of these techniques is to allow over commitment of  the ESXi hosts physical memory

Transparent Page Sharing

Transparent page sharing is a mechanism in which an ESX/ESXi host tries to conserve physical memory so that it will not have to resort to other memory management techniques. Transparent page sharing is enabled by default.

The VMkernel dynamically scans memory to look for duplicate pages. The VMkernel detects when different virtual machines have memory pages with identical content and arranges for those pages to be shared. That is, a single physical page is mapped into each virtual machine’s address space. If a virtual machine tries to modify a page that is shared, the VMkernel creates a new, private copy for that virtual machine and then maps that page into the address space of that virtual machine only. The other virtual machines continue to share the original copy.

When a virtual machine has been suspended and gets resumed, it does not immediately participate in the memory-sharing system. Its pages become shared over time. So if you intend to suspend and resume large batches of virtual machines, plan to have enough memory.

Balloon Driver

When a virtual machine must yield memory, the best thing is to let the guest operating system in the virtual machine select which pages of memory to give up. The virtual machine knows which pages have been least recently used and which pages can easily be refreshed from a backing store on disk.

The term “balloon driver” is an informal way of referring to the vmmemctl device driver, which is used to perform memory de-allocation or reallocation.

The balloon driver is installed when you install VMware Tools within the VM. The balloon driver’s function is to demand memory from the guest operating system and later to relinquish it, under the control of the VMkernel.

The guest operating system in the virtual machine is not aware of the communication taking place between the balloon driver and the VMkernel. The guest operating system is aware that the balloon driver is installed but is not aware of its purpose.

When a system is not under memory pressure, no virtual machine’s balloon is inflated. But when memory becomes scarce, the VMkernel chooses a virtual machine and inflates its balloon. That is, it tells the balloon driver in the virtual machine to demand memory from the guest operating system. The guest operating system complies by yielding memory, according to its own algorithms. The relinquished pages can be assigned by the VMkernel to other virtual machines.

Memory Compression

Memory compression can enable you to effectively use existing hardware and increase consolidation ratios by enabling greater virtual machine density per host. Memory compression is transparent to the guest operating system.

The process of compressing memory pages is much faster when compared to virtual machine paging operations because a normal page operation involves a disk I/O. The graphic illustrates how memory compression makes more host memory available in an attempt to prevent paging virtual machine memory out disk. For example, with memory compression, each memory page being considered for a swap operation is compressed and stored in a per-VM compression cache. In the example, memory pages A and B are compressed and stored as half-pages in the compression cache. Although both pages are removed from virtual machine guest memory, the actual reclaimed memory size is one page.


When a virtual machine is powered on, the system allocates a VMkernel swap file for it. The VMkernel swap file serves as a backing store for the virtual machine’s RAM contents. If a virtual machine cannot get enough memory through ballooning, the VMkernel forcibly reclaims memory from other virtual machines. The VMkernel copies the contents of the pages of these virtual machines to their corresponding swap files before giving the pages to the virtual machine that needs memory.

The size of the VMkernel swap file is determined by the difference between the virtual machine’s configured memory (or its memory limit) and its reservation.

Whenever VMkernel swap is being actively used, performance is not optimal. A good practice is to configure your hosts so that all normal running memory needs of the virtual machines (as determined by monitoring under load) can be accommodated using physical memory.

When the virtual machine is powered off, the VMkernel swap file of the virtual machine is deleted. When the virtual machine is powered back on, the VMkernel swap file for the virtual machine is re- created.

vSphere PowerCLI reference poster May 25, 2012

Posted by vbry21 in VMware blogs, VMware Training.
Tags: ,
add a comment

Yesterday I stuck a link for the vSphere 5.0 CLI reference poster onto the blog site, today as I’m still sitting on the optimise and scale course, I thought I’d be lazy and just give another link to another useful document that will come in very handy for anyone wanting to sit the vCAP-DCA 5, as according to the blue print for the exam there WILL BE POWERSHELL QUESTIONS.


I’ll be driving back to Newcastle upon Tyne today, so to quote Homer “Woo Hoo”, Homer Simpson not the Greek dude.


VMware Certified Advanced Professional Data Center Administrator v5 or vCAP-DCA 5 May 20, 2012

Posted by vbry21 in VMware Training.
Tags: ,
add a comment

The VMware Certified Advanced Professional – Data Center Administrator V5 (VCAP-DCA), it’s coming and so are the courses.

Today I’m heading off on a 300 mile-ish (new word I’ve just made up, it means about 300 miles or so) drive to Wokingham, “why” you may ask? “To sit on the train the trainer course for the new vSphere 5 Optimize and Scale course!”

This new course which is available as general release on 31st July 2012 is one of the recommended courses, along with the Fast Track or ICM course for the vCAP-DCA 5 certification.

So I’ll sit on the course and learn lots and lots of new stuff, which I’ll then hopefully pass onto lots of people sitting on my courses.

The link below will take you to the site with a datasheet listing all of the wonderful things covered on the course.


Now all I’ve got to do is pass the exam J