Techblog

Normally I do not link to other articles, but today I came accross this article and thought it was a critical piece of information for so many organizations planning for VMWare Clustering.

http://virtualfuture.info/2010/02/vsphere-cluster-max-4-esx-hosts-per-location-because-of-ha-limitations/

Here is a copy of the information incase the link dies.

vSphere cluster: max 4 ESX hosts per “location” because of HA limitations?
posted by Matthijs Haverink February 3, 2010Not a lot of info is found when you Google for manually selecting/fixing the primary HA nodes in a VMware VI or vSphere environment. Of course Duncan Epping has a couple of extremely interesting posts on Yellow-Bricks.com concerning HA even when it comes down to selecting or promoting the HA status of ESX nodes (a must read!), but I want more …

Let’s start with what I assume to know about HA:

- HA works with primary and secondary HA nodes
- The primary nodes are aware of the states and configs of all nodes in an HA cluster
- The secondary nodes depend on the primary nodes
- There is an supported limit of 5 primary HA nodes per cluster
- The first 5 ESX hosts that are added in a HA cluster are initially defined as primary HA nodes
- All the other hosts that are added to the HA cluster are configured as secondary HA nodes
- There’s a way to configure a HA node as primary or secondary, however it’s not possible to configure an ESX host as a “fixed” primary HA node:

/opt/vmware/aam/bin/Cli
AAM> promotenode (Configure host as a primary HA node)

/opt/vmware/aam/bin/Cli
AAM> demotenode (Configure host as a secondary HA node)

- One primary HA node is the Active Primary HA node; this node coordinates the restarts of the VM’s that went down with “crashed” host.
- When the Active Primary HA node goes down, another primary is (s)elected as Active Primary HA node” and takes over the coordinating role.
- A new primary is chosen when another primary is disconnected from the cluster in one of these situations:

(Re)configuring HA on a host
Disconnecting a host from the cluster (manually or by failure)
Removing a host from the cluster
In case of a HA failure
Putting a host into maintenance mode
Especially when you read the last bullet we can establish that HA roles are really dynamic in a VI/vSphere environment. This means that you have no control over the physical location of the primary and secondary roles.

And this is what my post is about:

This situation freaks me out because when you have a larger environment with a couple of possible failure domains as I’d like to call them (represented by any physically separated group of hosts within an HA cluster like different blade chassis or different server rooms) you want to have control over the placement of these HA roles.

And as I stated earlier Duncan Epping has some interesting articles like the HA deep dive and the Primary and Secondary nodes, pick one! which describe how to select a role for a host but this selection is not static; whenever a primary host is disconnected (Maintenance mode, Reconfigure HA and so on) there is a reelection and you lose control over the role placement.

So what if all 5 primaries HA nodes are on the same “possible failure domain” (say blade chassis) and that goes down? Well you just lost all your HA nodes that know what to do in case of a host-failure, so HA won’t work!

We’ll have to nuance the drama a bit: if 5 hosts of a “10 ESX host cluster” go down, you have a major issue anyway, if HA works or not, because you lost half of your capacity.

But you do have to realize that if HA is configured correctly, the 5 remaining hosts have some resources available, you have your primaries separated over the 2 locations and you have defined the start-up rules for the most important VM’s, these important VM’s will be booted up.

If you have the same situation as above but with all 5 primary HA nodes down because they were physically grouped, HA won’t work and none of the crashed VM’s will be booted up automatically!

During VMworld 2009 Marc Sevigny from VMware explained that they were looking into an option which would enable you to pick your primary hosts.This would solve the problem but until then the only solution is to keep your clusters limited to a total of 8 ESX hosts , 4 ESX hosts per “possible failure domain”.

I’m curious if I’m the only one running into this challenge; please let me know!

P.S. Special kudo’s go to Remon Lam from vminfo.nl who discovered this “feature” and reviewed the article .

Oracle, since acquiring Sun Systems, has been closing many of the open source projects that Sun once operated. This now includes OpenSolaris. You can see the end of life cycle announcement here:

http://www.sun.com/service/eosl/eosl_opensolaris.html

I am still shocked when an organization tells me that they do not have a complete asset management solution.  Often the reason provided is cost and while OCS lacks “fancy pants” it is my product of choice for organizations trying to reduce software cost. 

OCS supports all the major Windows and Linux, including MacOS X, operating systems.  The OCS Inventory NG Server only works on server based OS, but the agent is compatible with workstation and server OS.  Windows agents can even be deployed thru GPO.

OCS is released under the GNU Public License.  Which means the product is 100% free to use.

You can see all of the information you need, and the download, here:

http://www.ocsinventory-ng.org

Blackberry (RIS) is releasing a “FREE” version of the Blackberry Enterprise Server. The express version, as it is being called, can be found here: http://na.blackberry.com/eng/services/business/server/express/

It is basically a full version. Very little is held back and most of those features are geared toward large organizations.

LinkedIN and Microsoft are teamed up on the new outlook 2010 feature called the “social connector”. Showing that social networking has finally main stremed enough to enter the buisness place as part of one of the standards in business software.

You can read more about the Social Connector here:
http://blogs.msdn.com/outlook/archive/2009/11/18/announcing-the-outlook-social-connector.aspx

For those of you who are not apart of a controlled update system you may have experienced issues with the patches. If you are you should go to:
http://social.answers.microsoft.com/Forums/en-US/vistawu/thread/73cea559-ebbd-4274-96bc-e292b69f2fd1

It appears that only 32bit systems are effected.

10 years ago wireless technology was popping up everywhere.  Most of those technologies were found extremely unsecure and were updated or replaced and much of the credit goes to organizations like Wireless Ethernet Compatibility Alliance (WECA).  They gave us the 1st Wired Equivalent Privacy (WEP) solution.  It wasn’t very long before reports came out that WEP wasn’t very secure at all and many new technologies have emerged to prevent the largest problem, Stream Cipher Attacks.

First we need to discuss the 2 primary wireless security methods.  WEP spawned WEP2, WEP+, and Dynamic-WEP.  There other method is Wi-Fi Protected Access (WPA) which spawned WPA2.  All of these are based on the cryptograph RC4.

NOTE: RC4 is also used for SSL

Out of all of these the only two that should be used today is WPA2 and Dynamic-WEP, and here is why.

With the previous versions the “master” key is static and as a result a person could use a wireless packet sniffer to retrieve the information being sent to any user on a pre-dynamic key system.  Everything you sent out or requested from the wireless connection will be viewable as clear as day and all it requires is a wireless NIC card and a packet sniffer.  Much like the way that a brute force attack occurs the ‘hacker’ will scan the air traffic and then the packet sniffer will pattern match the bits.  This eventually yields the ‘master’ key which can then be used to reverse the encryption and will give the hacker everything sent/received.  Anyone can do this and if you’re not using WPA2 or Dynamic-WEP then you’re subjecting your users to tech theft of the highest degree.  Their email, passwords, usernames, and if they are truly being malicious they can use public security programs, like a Cisco VPN client, to access the network as you. 

This is also very important to remember as many people live exclusively on a wireless connection in hotels, remote work locations, and at home.  Everyday people find that their personal information has been stolen and billions are lost every year from cyber threats that often will originate from issues like this.  Sadly most hotels do not use dynamic encryption models and home equipment is rarely equipped or configured to use the more secure methods.  Standard WEP only needs a “password” and most people believe this to be secure.  

NOTE: Most network and IT service providers are unaware of the differences in WEP and WPA versions and technologies.  This is one of the primary ways hackers target SMB and because of SMB business practices this is an area that they are particularly vulnerable.  If you are currently using a “shared-key” I recommend that you change to a dynamic-key solution as quickly as possible.  For most SMB I recommend a WPA2-Radius configuration because users are able to login with their domain credentials and it is infinately more secure than any shared-key solution.  This solution is also easily available from most wireless connection devices.  You will also need to install and configure an additional component for AD/LDAP, but overall the setup is quick and easy.