rom the editors Virtual Desk


Hi everyone and welcome to the first newsletter of 2011. After an awesome 2010 I am really pleased to be able to bring you the TAM newsletter in 2011 again and I will do my best to report on the major news and information in our industry.


You will notice that this newsletter is in a different format. I am trying out a new service which I hope will provide all of us with a better experience for the newsletter and allow you to have a much richer experience in receiving the newsletter via your subscription. This is a trial phase of course so expect some issues as we get this off the ground and of course if you find any issues with this service please let me know.


As far as this weeks newsletter goes I have tried to include news from the end of last year and the beginning of this year as a bit of a catch up so I hope you enjoy this bumper first edition and as always stay in touch.


I would also like to send our best wishes to all of the Queenslanders who were affected by the recent floods and wish every one of you a speedy recovery.


Warm Regards
Neil Isserow (Newsletter Editor) and Paul James

VMware TAM Team




Blogs and latest news articles from around the web


Dynamic Cluster Pooling

2vcps and a Truck 21/12/10 6:26 AM Jon Owings capacity performance powershell

Dynamic Cluster Pooling is an idea that Kevin Miller ( @captainstorage) and I came up with one day while we were just rapping out some ideas on the whiteboard. It is an incomplete idea, but may have the beginnings of something useful. The idea is that clusters can be dynamically sized depending on expected workload. Today a VMware Cluster is sized based on capacity estimates from something like VMware Capacity Planner. The problem is this method requires you apply a workload profile across all time periods or situations. What if only a couple days of the month require the full capacity of a cluster. Could those resources be used elsewhere the rest of the month?


A Quick Review of VPLEX Storage Objects 13/12/10 10:00 PM slowe Storage Virtualization EMC SAN VPLEX

Now that I’ve managed to get my VPLEX clusters up and running, I’m ready to start providing some posts on VPLEX and how it’s configured and used. To get things started, I want to first provide an overview of VPLEX storage objects and how they relate to each other.

<aside>The images shown in this post are being served from Dropbox. If your office blocks Dropbox (like EMC does), then these images might not appear. I apologize for the inconvenience.</aside>


Some EMC Product Updates 17/12/10 1:47 AM slowe Storage Virtualization EMC VMware

There have been a few important EMC product updates over the last few days that I thought I might highlight here real quick:

Replication Manager has been bumped up to version 5.3.1 (also referred to as 5.3 SP1), which adds several new features. One of the more notable features is the ability to do file-level restores from both VMFS and NFS datastores. Other new features include the ability to create SnapView snaps or clones from RecoverPoint targets and expanded host and application support.


Using VPLEX and Data Replication Together 20/12/10 10:00 PM slowe Storage EMC VPLEX

In my previous post on EMC VPLEX, I provided a review of the VPLEX storage objects. In that post, I discussed the difference between a storage volume, an extent, a device, and a virtual volume. If you are unclear on the distinctions between those terms, I suggest you go back and read that post again before proceeding.

The following diagram illustrates these various storage objects again:


Arkeia vStorage Virtual Appliance Review

ESX Virtualization 13/12/10 2:32 AM Vladan SEGET Specials Arkeia vStorage Virtual Appliance

My test of Arkeia backup solution with vStorage Appliance.

Arkeia has released a new vStorage Virtual Appliance for vSphere. The new product can backup vSphere 4.x but also Virtual Infrastructure 3. You can backup your VMs present through vCenter, ESX or ESXi servers. The vStorage Appliance has built in vStorage Backup Agent which interacts with vStorage API and permits backups to disk, to tape, and to disk and then to tape (D2D2T). Those data can be then replicated locally or over a WAN environments.


Book review: VMware vSphere 4.1 HA and DRS technical deepdive

Gabes Virtual World 7/01/11 5:49 AM Gabrie van Zanten VMware deepdive drs ha

Many of you probably already heard about the book written by Duncan Epping and Frank Denneman on the ins and outs of HA and DRS. In December I received my copy and I finally finished it and must say...


How to re-enable the copy-paste between VI client and VM in vSphere 4.1

ESX Virtualization 20/12/10 9:34 PM Vladan SEGET Server Virtualization copy paste enable on ESX 4.1 copy paste enable on VM ESX 4.1 vSphere 4.1 copy paste enable

Re-enable the clipboard copy and paste functionality in vSphere 4.1

The security has been tightened in vSphere 4.1, so that’s why by default if you install vSphere 4.1 or if you upgrade your vSphere 4.0 installation, you can’t copy paste between the VI client and the VMs running in your vSphere environment.  You can read more about why it was changed in vSphere 4.1 in ESX 4.1 configuration guide (page 213). To be able to copy and paste between the guest operating system and the remote console, you must enable the Copy and Paste option.


How to activate the PAC when you purchase VMware product through a partner

ESX Virtualization 22/12/10 2:00 AM Vladan SEGET Videos License VMware activation process Partner Activation Code VMware Explained Vmware PAC

Partner Activation Code – (PAC) activation procedure.

PAC stays for Partner Activation Code. When customer buys a VMware product through an OEM partner, he’ll need to activate the PAC first to be able to get the License Activation Code (LAC)/Serial number. If the customer has been registered with VMware in the past, he’ll needs to sign in. Otherwise, he’ll have to register first.

The PAC is for single use. After its registration, the PAC is not needed anymore, since you’ll be able to get a serial at the end of the registration process.  After the PAC is registered, you’ll have to look for an email with the product serial # or LAC.   Also during the registration process you have the possibility to add the e-mail of the person who is responsible to administer the license.


How to make sure that the correct ISO image is loaded when Installing VMware Tools

ESX Virtualization 24/12/10 1:59 AM Vladan SEGET Server Virtualization Auto install disabled VMware Tools Install VMware Tools installation VMware tools ISO image

Checking if the ISO is loaded.

Sometimes you have a Windows VM with autostart for a CD drive disabled. In this case the VMware tools installation does not start automatically.  You can run into 2 different situations.

Case 1: The Vmware tools installer does not start:

01 - Click Start > Run from the inside guest operating system.
02 - Type D:\setup.exe where D: is the first CD-ROM drive configured for your virtual machine.
03 – Click OK to start installing VMware Tools.
Case 2: The setup fails to start as the ISO was not mounted to the CD-ROM drive:
01 - Right-click the virtual machine you want to install VMware Tools on, in your inventory. Choose Edit Settings.
02 – Select CD/DVD Drive.
03 – Make sure that the the connected check box is selected.
04 – Choose Datastore ISO file > Browse > vmimages > tools-isoimages > windows.iso
05 – Type D:\setup.exe again to start the installation


Suspend Power Policy in VMware View. Should you use it? 14/12/10 6:39 PM Andre Leibovici tips vdi virtualization VDI View view4.5

One of my readers posted a comment on my VDI Calculator page mentioning that he would not see the VM storage consumption increasing when Suspend VM option was select at “Desktop State when Not in use”.  Suresh Thoppay thanks for the comment!

According to Suresh, “ESX suspend file, which has a .vmss extension, is created if you set the desktop pool policy to suspend on logoff. The size of this file is equal to the size of guest RAM.”

His explanation is spot on! So I diligently reviewed my formulas and not satisfied with the results I performed some tests in my lab. It turns out that the original formula was working, however it was taking into consideration the difference between the total number of VMs and concurrent VMs.



Get hold of VDI IOPs, Read/Write Ratios and Storage Tiering 29/12/10 11:34 AM Andre Leibovici storage tips vdi virtualization VDI view4.5

Getting the right storage requirements for VDI can be tricky in most situations. The reason for that is the lack of information about the workload that will be running in each one of the virtual desktops. It is possible to use some pre-trended numbers as baseline, however despite this would be an indication of what the workload would likely be, it could be a point out of the curve in many cases. In the nirvana scenario the customer would have been already running a pilot and that data could be collected and trended.


VMware View 4.5 Events Database Explained 3/01/11 7:49 PM Andre Leibovici tips vdi virtualization VDI view45 Vmware

For my first article of the year I have chosen a subject that has not been much discussed, however greatly empower VMware View administrators.

VMware View 4.5 allows administrators to configure an external Microsoft SQL Server or Oracle database to record all VMware View events. Prior to View 4.5 the events database was integrated with the local ADAM database, not allowing for external Business Intelligence software integration.


Latest fling from VMware Labs - IOBlazer

NTPRO.NL - Eric Sloof 11/01/11 3:42 AM (Eric Sloof) Tools

VMware Labs presents its latest fling IOBlazer - a multi-platform storage stack micro-benchmark tool. IOBlazer started as a minimalist MS SQL Server emulator which focused solely on IO component. It has now matured into a scalable application with multi-platform support, capable of generating highly customizable workload by configuring parameters like:


New vSphere Troubleshooting video training by David Davis

NTPRO.NL - Eric Sloof 7/01/11 5:12 AM (Eric Sloof) Online Training

Fellow vExpert David Davis over at Train Signal has released the new vSphere Troubleshooting video training. This course took him 3 months to create, it’s almost 14 hours, and it’s made up of 30 videos. Like all the other training courses from Train Signal, it’s available via streaming online video (iPad compatible) and in the DVD offline format. In this course, David will educate you on how to troubleshoot vSphere networking, storage, management processes (and much more), from the GUI but especially from the CLI.


Enterprise Java Applications on VMware - Best Practices Guide

NTPRO.NL - Eric Sloof 23/12/10 5:44 AM (Eric Sloof) vSphere

VMware has released the "Enterprise Java Applications on VMware - Best Practices Guide". This paper discusses best practices for running Enterprise Java Applications on VMware vSphere virtual machines. The guidelines will help you to get the best from your Java applications and application servers when you run them on VMware vSphere.


Justifying SSDs

Pivot Point 14/12/10 12:51 PM drummonds Uncategorized fast ssd storage

Ever since I saw the results of VMware’s first performance work on EMC’s Enterprise Flash Drives (EFDs) I knew the storage world was about to change.  Even though I love the idea of SSD, I still struggle with the justification of their purchase.  I have had trouble quantifying the value of an EFD and fearlessly committing customers’ money to their purchase.  In this article I want to offer a few thoughts on these devices as I formulate my own ideas as to when SSDs are needed and how we can all enjoy their benefits.


vCenter Custom Alarms: Instruction, Tips, Tools

Pivot Point 11/01/11 6:50 PM drummonds Uncategorized alarms vcenter vspecialists

Half a year ago the Asia Pacific vSpecialist team made a fantastic acquisition in one David “Two Screws” Lloyd. David previously worked for a wonderful VMware and EMC customer in the UK and moved back to Australia. That is when we jumped on the opportunity to snap him up. In working with him in the labs recently, I have come to realize that David has incredible depth and breadth in the space of virtual infrastructure management.


VMware View for Noobs (A Collection of Resources)

Professional VMware 14/12/10 1:40 AM bunchc VMware vSphere view resources


I had a friend ping me the other day with something along the lines of:

“OMG VDI with View is hard!”

For said friend, IT isn’t his day job, but alas, the business had a need and he needed an answer. Myself, I’m not as familiar with View as I could be, and thus reached out to the Twitter verse to see what the best resources for “Noobs” are:


Cloudy Thoughts

RTFM Education 15/12/10 1:51 AM Mike Laverick Cloud

I’ve been thinking about the cloud a lot in the last year – and speaking to both the sellers of cloudy software, as well as customers thinking of going down the cloud route. For sometime I’ve though the cloud might be more attractive to SMB customers – not so much the private cloud obviously, but the public cloud. After all if I’m small business or start-up why would want all the grief and hassle of managing my own physical or virtual infrastructure when I can have VMs outsourced to a third party. Well, any more of this theme on over on TechTarget’s site where I’ve written an article about this subject..


ISV Support – The biggest barrier to virtualization

RTFM Education 15/12/10 2:03 AM Mike Laverick Other

One of the things that is often discussed is what the biggest barriers are to virtualization – frequently this discussions focus on performance, internal politics and cost of licensing. But have you ever thought that one of the biggest barriers to virtualization – is the very software vendors? Quite often their support/EULA statements are rubbish, and they deliberately frame the licensing to make it cost prohibitive to virtualize. Often the motivation to do this – is to stick to one of their competitors. So much for the helping the customer over come their “challenges” huh. I wax lyrical about this – using Oracle as an example – over on TechTarget.


ESXi has a 32mb Memory footprint

Technodrone 29/12/10 9:00 PM Maish 4.1 VMware ESX4i vSphere

I was listening to an very interesting presentation this evening from Olivier Cremel, Principal Engineer
ESXi Internals: Better Understanding for Better Management and Troubleshooting

The ESXi Architecture document actually states that the memory footprint of the hypervisor is 32mb


Hyper-V [Not Exactly] Dynamic Memory

VCritical 21/12/10 8:29 AM Eric Gray Virtualizationism Hyper-V memory overcommit vSphere

Hyper-V is nearing the end of a long march to memory overcommit when they finally release Dynamic Memory early next year in Service Pack 1, but please do not call it “overcommit” when Microsoft Virtualization is around — it really riles them up.  Just think of this new Dynamic Memory feature as memory thin-provisioning; each VM has the potential to utilize more physical memory as demand grows, just as long as another VM doesn’t request it first.


vComeback Contest: Microsoft Cloud Power Billboard

VCritical 10/01/11 9:00 PM Eric Gray Virtualizationism cloud Microsoft

Microsoft recently plastered this giant attack ad on a key Silicon Valley passageway — Northbound Highway 101 in Mountain View:


Fun fact: The billboard on the opposite side is running an Apple iTunes ad.


Catchy, yet sophisticated and original.

Your witty comeback could win you a cool vSphere book!

Got a pithy response to this new Microsoft cloud marketing line?  Share it with the virtualization community by submitting a comment below for a chance to win a great prize.

The possibilities are endless.  Keep it clean.

For instance, you might reply:  “Yeah, I’d say the exact same thing if my virtualization was Hyper-V.”


Home Lab Setup : VLANs and Routing

vFAIL.NET 20/12/10 10:00 PM Sean Crookston VMware dd-wrt. vlan routing lab


A few months back I began thinking about doing a few things to my home lab setup to give it a little extra in terms of the capabilities it had. One thing near the top of my list was beefing up the network side of things a little bit.

Originally I had just the two hosts hooked up to a couple of 8 port gigabit switches. For the most part this was perfectly fine as I had full gigabit connectivity along with Jumbo frames. What was lacking though was manageability of the switch and VLANs.


vCenter 4.1 Upgrade – Error 1719 The Windows Installer Service Could Not Be Accessed

vFAIL.NET 3/01/11 11:00 PM Sean Crookston VMware vcenter 4.1 upgrade vsphere


Upon attempting to upgrade a vCenter server to 4.1 I was presented with and error like the below.

Error 1719 – The Windows Installer Service could not be accessed

My first thoughts were around how I would have to build a new vCenter server because the Windows Installer Service was completely hosed. After some initial troubleshooting I was still not able to get the install working, however a quick search for vcenter and error 1719 presented me with a solution that resolved a similar issue with VMware Tools installations on Windows 2008 x64 operating systems.

The issue was simply related to a registry key that when set only allows the Windows Installer service to handle 32 bit installers. Why it was set like this on the machine or that you’d event want this ‘capability’ I have no idea.


The solution as posted in the kb article here for VMware Tools is


VCAP-DCA/VCAP-DCD Blueprints Updated

vFAIL.NET 10/01/11 11:00 PM Sean Crookston VCAP-DCA VCAP-DCD VMware certification



A few days ago it looks like both the VCAP-DCA and VCAP-DCD blueprints were updated to reflect new information.


Being fairly familiar with the last couple versions of the blueprint I took a look at the new version (1.6) and see no real differences. I’m sure there is something but I could not find it so please comment if you see any of the differences.


It is now confirmed via the blueprint that the exam is 113 questions. These questions are a mixture of multiple-choice, drag-and-drop, and design items using an in-exam design tool. Like the VCAP-DCA update I don’t see any real differences here either, although I am less familiar with this blueprint at this time.


Understanding vSphere Disaster Recovery/Avoidance options

Virtual Geek 21/12/10 7:40 AM Chad Sakac

Wrapping up all the blog posts in one place, and including a webcast and powerpoint on the topic.

Phew – that was a lot of work, right in the middle of the 2011 planning cycle :-)

The blog series is: “Understanding vSphere Disaster Avoidance/Recovery” – discussing a broad topic: state of the union of vSphere non-disruptive disaster avoidance and disaster recovery solutions, and how they interact (because it ain’t easy to do both together when you dive in deep).

Read Post I: Discusses the 4 key solution categories in this space.  Read it here.

Read Post II: Discusses one of solution (stretched vSphere cluster and VPLEX) and gory failure scenarios in detail.  Read it here.

Read Post III: Discusses what’s going on in this space (and where EMC R&D efforts are centered).  Read it here.


Uptime: Helping you to install SRM!

VMware Blogs 17/12/10 8:23 AM

Hello everyone,

I have some resources to share with you to make it a little easier to install SRM, but I wanted to make sure first that everyone understands that making SRM work is just a small part of a DR project, and while sometimes a little complicated, it is generally the easist part of the DR project.  That is why I often recommand people involve outsiders in the form of professional services in a DR project as their experience can often help greatly to make a project successful.  Not just with SRM, but also in the rest of the project.


VROOM!: Performance Scaling of an Entry-Level Cluster

VMware Blogs 18/12/10 6:18 AM

Performance benchmarking is often conducted on top-of-the-line hardware, including hosts that typically have a large number of cores, maximum memory, and the fastest disks available. Hardware of this caliber is not always accessible to small or medium-sized businesses with modest IT budgets. As part of our ongoing investigation of different ways to benchmark the cloud using the newly released VMmark 2.0, we set out to determine whether a cluster of less powerful hosts could be a viable alternative for these businesses. We used VMmark 2.0 to see how a four-host cluster with a modest hardware configuration would scale under increasing load.


VMware Support Insider: Purpose-built guest OS datastores - Don't do it!

VMware Blogs 21/12/10 12:45 AM

Today we have a guest post from Duncan Armstrong, who is a Tech Support Engineer in our Canadian office who specializes in Fault and Storage issues. He’s currently focused on writing Knowledgebase articles as we want to capture as much real-world troubleshooting know-how as possible and share it with everyone. Today, he wants to give us some advice.


VMware vCloud Blog: Cloud Architecture Patterns: Service VM

VMware Blogs 21/12/10 11:14 AM

By Steve Jin, VMware R&D


Provide an easy way to provision new infrastructure and application services for a computing cloud




To run a large-scale computing infrastructure, you will need many different types of services, including compute, storage, and networking, among others. After virtualization has successfully detached compute from the physical hardware, it’s very easy to provision and scale compute. But compute requires storage and networking which are lagging behind. To maximize the benefits of virtualization and cloud computing, it’s natural to push the storage and networking in the same direction.

Looking beyond the infrastructure to consider applications, we need various types of services such as database, directory, messaging, and more. I’ve covered the App VM pattern that allows using IaaS for PaaS in a previous blog. While you can pack some of these services into an application VM, the problem is that it scales well but does not follow the aspectual centralization pattern.


VMware Support Insider: Changes to Snapshot Consolidation

VMware Blogs 24/12/10 6:25 AM

Another guest post today from Simon Todd, who is a Tech Support Engineer in our Cork, Ireland office who specializes in Storage issues.

Anyone using snapshots has probably run into this issue once, twice or many times:

When trying to perform an online consolidation there is not enough space on the Datastore to perform the consolidation.

This is mainly due to the way snapshots are consolidated. To illustrate this, let’s look at an example where we have a virtual machine residing on a 600Gb VMFS Datastore that has a 500Gb base disk, and that virtual machine has 8 levels of snapshots of the following sizes:


VMware ThinApp Blog: Locally installed applications and integration with virtualized Internet Explorer

VMware Blogs 4/01/11 12:14 AM

Perhaps one of the hottest use cases for ThinApp currently is virtualizing Internet Explorer 6. I have found a somewhat generic fix to make integration between virtualized IE6 and locally installed applications. The fix is discussed in a previous blog post ( but might not be that obvious.


VMTN Blog: EMC Solutions for VMware webcasts scheduled for January

VMware Blogs 4/01/11 5:56 AM

Happy New Year everyone! Hope you had a good time ringing in 2011.

Our friends at EMC have scheduled a number of new webcasts for January, covering solutions for using EMC technology with VMware. All January webcasts will be held at 11:00 a.m. on Thursdays.

The Value of VMware Integration
Thursday, January 6, 2011 - 8 am PT / 11 am ET / 16:00 GMT
Learn about the benefits of tight VMware integration, and find out how EMC's 60+ points of integration with VMware enhance the performance, scalability, security, and ease-of-management of virtual environments.

Deploying Virtual Desktop Infrastructure to Accelerate EHR Adoption
Thursday, January 13, 2011 - 8 am PT / 11 am ET / 16:00 GMT
Hear Columbia Memorial Hospital discuss how the EMC Virtual Desktop Infrastructure Solution for Healthcare helps solve the challenge of ever-increasing costs--while increasing clinical productivity, improving workflow, and securing patient information.

Automate Unified Recovery of VMware Hosts
Thursday, January 20, 2011 - 8 am PT / 11 am ET / 16:00 GMT
Learn about strategies for protecting data within a unified storage infrastructure. Discover how to define protection policies, identify protection gaps, and prove compliance, as well as instantly recover from data corruption with DVR-like rollback.

Simple, Efficient, Powerful - Optimizing Your Virtualized Applications
Thursday, January 27, 2011 - 8 am PT / 11 am ET / 16:00 GMT
Find out how our unified storage solutions can help you utilize resources to efficiently and dynamically embrace virtualization, and boost your infrastructure performance--with a 20% guarantee.


VROOM!: Experimenting with Cluster Scale-Out Utilizing VMmark 2

VMware Blogs 8/01/11 1:51 AM

The first article in our VMmark 2 series gave an in-depth introduction to the benchmark while also presenting results on the scaling performance of a cluster based on a matched pair of systems.  The goal of this article is to continue to characterize larger and more diverse cloud configurations by testing scale-out performance of an expanding vSphere cluster.  This blog explores an enterprise-class cluster’s performance as more servers are added and subsequently the amount of work being requested is increased. Determining the impact of adding hosts to a cluster is important because it enables the measurement of the total work being done as cluster capacity and workload demand increases within a controlled environment.  It also assists in identifying the efficiency with which a vSphere managed cluster can utilize an increasing number of hosts.


VMware ThinApp Blog: ThinAppTV Has Arrived!!

VMware Blogs 12/01/11 11:09 AM


Calling all ThinApp'ers. Oprah may have her "OWN" network, but we have ThinAppTV!!! So, sign up with Vimeo and start uploading your videos. The ThinApp team will start adding them to the channel so everyone can have a resource for all of the cool stuff in and around ThinApp in one place. In addition, the ThinApp team will also start uploading videos with the cool "tips and tricks" that you often see us talk about on the Blog.  Tune in at


Oracle RAC Performance on vSphere 4.1

VROOM! 17/12/10 6:21 AM Todd Muirhead



Oracle Real Application Clusters (RAC) is used to run critical databases with stringent performance requirements. A series of tests recently were run in the VMware performance lab to determine how an Oracle RAC database performs when running on vSphere. The test results showed that the application performed within 11 to 13 percent of physical when running in a virtualized environment.



HA Cluster Improvements

vSphere PowerCLI Blog 16/12/10 7:48 PM Vitali Baruh

PowerCLI 4.1.1 introduces three new improvements for HA clusters:

Ability to edit advanced HA cluster settings

Cmdlet that retrieves the primary nodes of HA cluster

Set of new properties that contain runtime HA information


The first of the new features is the ability to edit the advanced settings of HA clusters. There are four new cmdlets that allow you to customize HA settings - Get-AdvancedSetting, New-AdvancedSetting, Set-AdvancedSetting, and Remove-AdvancedSetting.


Shares set on Resource Pools

Yellow Bricks 15/12/10 12:32 AM Duncan Epping Server Various 4.0 4.1 drs resource pools VMware vSphere

During our session at the Dutch VMUG Frank was explaining Resource Pools and the impact of limits and reservations. As I had the feeling not everyone in the room was using resource pools I asked the following questions:


vCenter and Memory metrics

Yellow Bricks 21/12/10 12:43 AM Duncan Epping Server Various 4.1 vcenter vSphere

I received a question last week from a former colleague around some of the memory details in vCenter. There are a couple of places where memory details are shown on a “VM level” within the vCenter client. The first tab that we will discuss is the Summary tab. It shows “General” and “Resources”. It appears that there is a lot of confusion around this topic and that probably comes from the fact that some of the Performance Metrics are named similarly but don’t always refer to the same.


How cool is TPS?

Yellow Bricks 11/01/11 3:39 AM Duncan Epping Server 4.1 esxtop memory performance tps troubleshooting VMware vSphere zero

Frank and I have discussed this topic multiple times and it was briefly mentioned in Frank’s excellent series about over-sizing virtual machines; Zero Pages, TPS and the impact of a boot-storm. Pre-vSphere 4.1 we have seen it all happen, a host fails and multiple VMs need to be restarted. Temporary contention exists as it could take up to 60 minutes before TPS completes. Or of course when the memory pressure thresholds are reached the VMkernel requests TPS to scan memory and collapse pages if and where possible. However, this is usually already too late resulting in ballooning or compressing (if your lucky) and ultimately swapping. If it is an HA initiated “boot-storm” or for instance you VDI users all powering up those desktops at the same time, the impact is the same.