Archive for January 2012

Virtual vCenter – Pros and Cons

January 19, 2012 vCenter No comments

Over the years there have been some controversy over this topic. Should vCenter Server be a physical or a virtual machine?

The most important aspect is that both solutions are supported by VMware.

http://www.vmware.com/pdf/vi3_vc_in_vm.pdf

Physical Solution Pro’s

  • More scalable
  • Hardware upgrades can be carried out
  • It is not susceptible to a potential VI outage

Physical Solution Cons

  • A dedicated physical server is required
  • Extra Power usage
  • Extra cooling considerations
  • UPS considerations
  • Backup must be done using tradition tools
  • DR may be more difficult

Virtual Solution Pro’s

  • You do not need a dedicated physical server (a way to reach a greater consolidation)
  • Server Consolidation: instead of dedicating an entire physical server to VirtualCenter, you can run it in a virtual machine along with others on the same ESX Server host.
  • Mobility: by encapsulating the VirtualCenter server in a virtual machine, you can transfer it from one host to another, enabling maintenance and other activities.
  • Each backup solution that works for a VM work also in this case
  • Snapshots: A snapshot of the VirtualCenter virtual machine can be used for backup,
    archiving, and other similar purposes.
  • Availability: using VMware HA, you can provide high availability for the VirtualCenter server
  • You can via DRS rules place the vCenter on certain hosts so you know where it is.

Virtual Solution Con’s

  • It is susceptible to a potential VI outage
  • No cold migration
  • No cloning
  • It must contend for resources along with other VMs
  • If you wish to modify the hardware properties for the VirtualCenter virtual machine, you will need to schedule downtime for VirtualCenter. Then, you will need to connect to the ESX Server host directly with the VI Client, shut down the VirtualCenter virtual machine, and make the modifications.
  • Careful consideration and design thinking needs to built into a vSphere environment where a vDS will be used – See below

Virtual vCenter and vDS

VMware specifically state about running vCenter within a distributed switch and they said point blank, “it is not supported”. They said “Because vCenter governs the distributed switch environment, you can’t have vCenter within the distributed switch.”

If you lose your Virtual Center you will have no way in moving virtual machines between different port groups on the vNetwork Distributed Switch. In addition, you will not be able to get a virtual machine from the traditional virtual switch to a port group on the vNetwork Distributed Switch. Extra to that, you can’t move a VM to another VMware vNetwork Distributed Switch. So that means if you are using VMware vSphere vNetwork Distributed Switches & you lose virtual center you are almost disabled on the networking part. If you lose connectivity on the classic virtual switch & your adapter on the distributed switch are OK you still can’t move your virtual machines to that distributed switch till Virtual Center is back.”

Does this mean a virtual infrastructure design should keep a vSS around? I would say “yes!”. Perhaps it’s now more important to dedicate 2 of the ESX host’s pNICs for the ESX Service Console / ESXi Management VMKernel isolated as a vSS. The 2 pNICs are not only for redundancy anymore, but also to support one or more standby VM portgroups in case they’re needed as a recovery network for VMs normally using the vDS. Of course, that means creating the appropriate trunking, and VLANs ahead of time. Have everything ready for a quick and easy change of critical VMs when needed.

Therefore, a hybrid design using both a vSS and a vDS is a smart “safety net” to have. Especially when an admin has to point the vSphere client directly at an ESX/ESXi host. The “safety net” vSS portgroups will be available from each host and the VMs can be easily switched via the vSphere Client GUI.

See this useful article by Duncan Epping

http://www.yellow-bricks.com/2012/02/08/distributed-vswitches-and-vcenter-outage-whats-the-deal/

In the event that the worst happens and you lose connectivity

VMware has provided a KB Article 1010555 which will allow an admin to create a vSS and move the vCenter VM on to this switch

KB1010555

iPad2 and Kindle App

January 19, 2012 Technology No comments

In typical Apple fashion, the iPad 2 isn’t a massive overhaul but a refinement, leaving much of the original intact. It looks very similar, the screen is the same 9.7in, 1,024 x 768 IPS unit as before, and even where significant new features have been added (the cameras, for instance), there’s plenty of room for improvement.

To start with, the new iPad is smaller and lighter than before: it weighs just a whisker over 600g and measures a mere 186 x 9 x 241mm. Its slenderness is striking. The new iPad is actually half a millimetre slimmer than the iPhone 4, and 4.6mm thinner than the original iPad. That’s some feat of engineering, and with its lighter weight and flat back the iPad 2 feels significantly more comfortable in the hand than the original.

The controls have been left alone, though: the home button remains at bottom-centre, with the volume and hold switch on the right edge at the top. The power switch remains on the top edge on the right-hand side, with the 3.5mm headphone/microphone socket opposite it along the same edge, and the Apple USB interface stays on the bottom edge.

Apple has built magnets into the left edge of the iPad 2, allowing the new optional cover to snap satisfyingly into place. Expected to cost about £25, the cover is divided into four segments with a hinged spine that snaps neatly over the iPad’s magnetic edge. It not only protects the screen, but can be used as a stand for typing or watching movies. This cover is absolutely brilliant for travelling.

There are more changes under the hood, with an updated CPU, a new GPU and a doubling of the original iPad’s 256MB RAM. The CPU is the most interesting update, replacing the single-core 1GHz Apple A4 processor with the dual-core A5. In real-world use it’s immediately obvious that the iPad 2 is a much faster and more responsive device than its predecessor

Amazingly, the iPad 2’s stamina easily surpasses that of its predecessor. In tests the first iPad lasted 13hrs 44mins and in further tests even more impressive battery life produced 16hrs 49mins of use

iPad 2 UK pricing starts at £399 for the 16GB Wi-Fi only model, and jumps up to £659 for the 64GB Wi-Fi + 3G edition.

Other models are priced as follows: 32GB Wi-Fi only at £479, 64GB Wi-Fi only at £559, 16GB Wi-Fi + 3G at £499 and 32GB Wi-Fi + 3G at £579

The Kindle app is optimized for the iPad, iPhone, and iPod touch, giving users the ability to read Kindle books, newspapers, magazines and PDFs on a beautiful, easy-to-use interface. You’ll have access to over 900,000* books in the Kindle Store. Amazon Whispersync automatically syncs your last page read, bookmarks, notes, and highlights across devices (including Kindle), so you can pick up your book where you left off on another device.

Email documents to your new Send-to-Kindle e-mail address and Amazon deliver them to your device. The documents are automatically archived in the Amazon Cloud and available for re-download on your iOS or supported Kindle devices.

Electric Monk?

January 19, 2012 Personal No comments

Why Electric Monk?

The Electric Monk can be found in one of my favourite books – Dirk Gently’s Holistic Detective Agency. The Book is a humorous fantasy detective novel by Douglas Adams, first published in 1987. It is described by “the author” on its cover as a “thumping good detective-ghost-horror-who dunnit-time travel-romantic-musical-comedy-epic”.

The central motif of Dirk Gently’s Holistic Detective Agency is the fundamental interconnectedness of all things which is in part how much of IT works. You can’t have virtualisation without networking and storage, you get the gist

Dirk Gently‘s plot is non-linear, partly because time travel is one of the main elements of the story

Electric monks are coincidentally humanoid robots designed to practice religion in their owners’ stead. This particular monk had accidentally been connected to a video recorder and, in attempting to believe everything on the TV, had malfunctioned and begun to believe “all kinds of things, more or less at random”, including things like tables being hermaphrodites and God wanting a lot of money sent to a certain address. Since it was cheaper to replace the Monk than to repair it, the Monk was cast out in the wilderness to believe whatever it liked. The Monk also owns a somewhat cynical horse, which he was allowed to keep because “horses were so cheap to make”. Upon his arrival on Earth, the Monk has several humorous misadventures.

Four billion years in Earth’s past, a group of Salaxalans attempts to populate the earth; however, a mistake caused by their engineer – who used an Electric Monk to irrationally believe the proposed fix would work – causes their landing craft to explode, killing the Salaxalans and generating the spark of energy needed to start the process of life on Earth. The ghost of the Salaxalan engineer roams the earth waiting to undo his mistake, watching human life develop and waiting to find a soul that it can possess. The ghost finds it can only possess individuals that fundamentally want to do the same task it is trying to accomplish itself. Otherwise, it is only able to influence the individual in subtle ways