As of today, our book “vSphere 4.1 HA and DRS Technical Deepdive” can be ordered via ComputerCollectief. Computercollectief is a dutch computer book and software reseller and ships to most European countries. Using Computercollectief, we hope to evade the long shipping times and accompanying costs.
Go check it out. http://www.comcol.nl/detail/73133.htm
Comcol expect to be able to deliver at the end of this month.
Dutch vBeers
Simon Long of The SLOG is introducing vBeers to Holland. I’ve copied the text from his vBeers blog article.
Every month Simon Seagrave and I try organise a social get together of like-minded Virtualization enthusiasts held in a pub in central London (and Amsterdam). We like to call it vBeers. Before I go on, I would just like to state, although it’s called vBeers, you do NOT have to drink beer or any other alcohol for that matter. This isn’t just an excuse to get blind drunk.
We came up with idea whilst on the Gestalt IT Tech Field Day back in April. We were chatting and we both recognised that we don’t get together enough to catch-up, mostly do to busy work schedules and private lives. We felt that if we had a set date each month, the likely hood of us actually making that date would be higher than previous attempts. So the idea of vBeers was born.
The first Amsterdam vBeers will be held on Thursday 16th of December starting at 6:30pm in ‘Herengracht Cafe’ which is placed close to Leidseplein and Dam Square. This venue serves a fine of selection of beers along with soft drinks and bar food.
Drinks will not be paid for, there will not be a tab. When you buy a drink please pay for it as no one else will be paying for your drinks.
* Location: The ‘Herengracht Cafe‘ Amsterdam
* Address: Herengracht 435, Herengracht/Leidsestraat
* Nearest Tram Station: Koningsplein – Lijn 1,2,5
* Time: 6:30pm
* Location: Map
HA and DRS Technical deepdive available
After spending almost a year on writing, drawing and editing, the moment Duncan and I waited for finally arrived… Our new book, the vSphere 4.1 HA and DRS technical deepdive is available on CreateSpace and Amazon.com.
Early this year Duncan approached me and asked me if I was interested in writing a book together on HA and DRS, without hesitation I accepted the honor. Before discussing the contents of the book I would like take the opportunity to thank our technical reviewers for their time, their wisdom and their input: Anne Holler (VMware DRS Engineering), Craig Risinger (VMware PSO), Marc Sevigny (VMware HA Engineering) and Bouke Groenescheij (Jume.nl). And a very special thanks to Scott Herold for writing the foreword!
But most of all I would like to thank Duncan for giving me this opportunity to work together with him on creating this book. The in-depth discussions we had are without a doubt the most difficult I have ever experienced and were very interesting, both most of all fun! Thanks!
Now let’s take a look at the book.Please note that we are still working on an electronic version of the book and we expect to finish this early 2011. This is the description of the book that is up on CreateSpace:
About the authors:
Duncan Epping (VCDX 007) is a Consulting Architect working for VMware as part of the Cloud Practice. Duncan works primarily with Service Providers and large Enterprise customers. He is focused on designing Public Cloud Infrastructures and specializes in bc-dr, vCloud Director and VMware HA. Duncan is the owner of Yellow-Bricks.com, the leading VMware blog.
Frank Denneman (VCDX 029) is a Consulting Architect working for VMware as part of the Professional Services Organization. Frank works primarily with large Enterprise customers and Service Providers. He specializes in Resource Management, DRS and storage. Frank is the owner of frankdenneman.nl which has recently been voted number 6 worldwide on vsphere-land.com
VMware vSphere 4.1 HA and DRS Technical Deepdive zooms in on two key components of every VMware based infrastructure and is by no means a “how to” guide. It covers the basic steps needed to create a VMware HA and DRS cluster, but even more important explains the concepts and mechanisms behind HA and DRS which will enable you to make well educated decisions. This book will take you in to the trenches of HA and DRS and will give you the tools to understand and implement e.g. HA admission control policies, DRS resource pools and host affinity rules. On top of that each section contains basic design principles that can be used for designing, implementing or improving VMware infrastructures.
Coverage includes:
• HA node types
• HA isolation detection and response
• HA admission control
• VM Monitoring
• HA and DRS integration
• DRS imbalance algorithm
• Resource Pools
• Impact of reservations and limits
• CPU Resource Scheduling
• Memory Scheduler
• DPM
We hope you will enjoy reading it as much as we did writing it. Thanks,
Eric Sloof received a proof copy of the book and shot a video about it.
Should or Must VM-Host affinity rules?
VMware vSphere 4.1 introduces a new affinity rule, called “Virtual Machines to Hosts” (VM-Host), which I described in the article “VM to Host affinity rule”. A short recap: VM-Host affinity rules are available in two flavors:
- Must run rules (Mandatory)
- Should run rules (Preferential)
By providing these two options a new problem arises for the administrator\architect, when will the need occur for using the mandatory rule and when is it desired to use preferential rules?
I think it all depends on the risk and limitations introduced by each rule. Let’s review difference between the rules, the behavior of each rule and the impact they have on cluster services and maintenance mode.
What is the difference between a mandatory and a preferential rule?
- A mandatory rule limits HA, DRS and the user in such a way that a virtual machine may not be powered on or moved to a ESX host that does not belong to the associated DRS host group.
- A preferential rule defines a preference to DRS to run virtual machine on the host specified in the associated DRS host group.
How does HA treat preferential rules?
VMware High Availability respects mandatory rules and obey mandatory rules when placing virtual machines after a host failover. It can only place virtual machines on the ESX hosts that are specified in the DRS host group. DRS does not communicate the existence of preferential rules to HA, therefore HA is not aware of these rules. HA cannot prevent placing the virtual machine on a ESX host that is not a part of the DRS host group, thereby violating the affinity rule. DRS will correct this violation during the next invocation.
How does DRS treat preferential rules?
During a DRS invocation, DRS runs the algorithm with preferential rules as mandatory rules and will evaluate the result. If the result contains violations of cluster constraints; such as over-reserving a host or over-utilizing a host leading to 100% CPU or Memory utilization, the preferential rules will be dropped and the algorithm is run again.
Limitations
In essence a VM-Host affinity rule restricts the number of hosts on which the virtual machines may be powered-on or to which virtual machines may migrate. Setting VM-Host affinity rules can limit load-balancing and evacuation for maintenance mode.
Load-balancing limitations
A certain level of risk is introduced when Mandatory VM-Host affinity rules are used. As a result of the restrictive behavior by only allowing virtual machines to start on ESX host associated in the DRS host group, it impacts HA’s ability to select a compatible ESX host to place the virtual machine.
In addition, using mandatory VM-Host affinity rules reduce the virtual machine placement options used by DRS when defragmenting the cluster. When using the HA “Percentage based” admission control resource fragmentation could occur.
During a failover a defragmentation will be requested by HA from DRS. DRS tries to migrate virtual machines to regain enough unfragmented resources to fit and start all virtual machines. Because DRS is allowed to use “multi-hop” migrations, DRS calculations usually creates “chain” of migrations during defragmentation of a host. For example: VM-A migrates to host 2 and VM-B migrates from host 2 to host 3. Mandatory rules narrow the playing field, allowing VM to only move around in associated DRS host group, reducing the overall options to transport virtual machines around the cluster, regardless of association with VM-host affinity rules.
Maintenance mode
DRS will not violate CPU and memory reservation to obey mandatory VM-Host affinity rules and it will not violate mandatory rules to allow reservations to be honored. During placement both requirements must be met and therefore DRS will only place a virtual machine if its reservation and the mandatory rule can be satisfied. This behavior will impact the ability of DRS to select a suitable compatible host to the place virtual machines during maintenance mode automated evacuations.
Conclusion
Well, it’s up to you to decide which rule is appropriate to use for separating workloads across the ESX hosts in the cluster. By knowing the impact and limitations introduced by mandatory rules, one might be able to make an informed decision.
Disallowing multiple vm console sessions
Currently I’m involved in a high-secure virtual infrastructure design and we are required to reduce the number of entry points to the virtual infrastructure. One of the requirements is to allow only a single session to the virtual machine console. Due to the increasing awareness \ demand of security in virtual infrastructure more organizations might want to apply this security setting.
1. Turn of the virtual machine.
2. Open Configuration parameters of the VM to edit the advanced configuration settings
3. Add Remote.Display.maxConnections with a value of 1
4. Power on virtual machine
Update: Arne Fokkema created a Power-CLI function to automate configuring this setting throughout your virtual infrastructure. You can find the power-cli function on ICT-freak.nl.