VMware Cloud Environment Enterprise level virtual datacentre: providing highly redundant, fast and scalable solutions. An eukhost Technical White Paper. Page 1
Introduction... 3 Traditional physical solutions... 3 Issues with master/slave and clustered configurations... 3 Virtualisation... 3 How VMware handles redundancy.... 3 Why virtualisation is better for your solution.... 4 Are there any limitations to virtualisation?... 4 How will my virtual server perform?... 4 Is my data safe?... 4 Does virtualization offer any other features?... 5 Flexibility... 5 Easy upgrades and downgrades... 5 Live storage migrations... 5 Private internal networking... 5 Technical diagrams... 6 Storage network... 6 Internet access... 7 Page 2
Introduction Virtualization has been slowly revolutionising computing for over 10 years now. When we undertook the challenge of building a new VMware environment, we decided that it should encompass the best that virtualisation had to offer whilst rivalling the performance of traditional physical server-based solutions. To help overcome this challenge, we looked to VMware, who are arguably the leaders in the virtualisation market. Traditional physical solutions Physical servers are flexible and allow us to create some excellent solutions to various IT challenges. However, all dedicated solutions suffer from the same drawback: hardware failure. The only way to negate hardware failure is to use redundant hardware. This can be done in master/slave configurations or, more commonly these days, by clustering services on multiple hardware platforms. Issues with master/slave and clustered configurations Unfortunately, more hardware means two things: a more costly solution and a more complex solution. A master/slave setup offers N+1 redundancy. If you require more than this then you will need to look at complex clustered solutions. What all this means in real terms is that you end up paying out good money for hardware that, if you re lucky, you will never use. These factors are the main driver behind the development of virtualisation technology. Virtualisation In its simplest terms, virtualisation is a way of taking a physical server and partitioning it into many virtual servers. Thanks to Hypervisor-based virtualisation technology (VMware), each VM (virtual machine) has its own distinct set of resources that is accessed at a hardware level. VMs are completely unaware of each other and do not contend for each other s resources. From your perspective a VM will look and behave exactly like a physical dedicated server. How VMware handles redundancy. Virtual hosts are still physical servers, suffering from the same issues (such as hardware failure) as a traditional physical server environment. These hardware failures are dealt with in exactly the same way as in physical environments. Multiple components such as power supplies are standard across our VMware cloud environment but it is clustering that really brings this product into its own. Our cloud VMware environment is actually a large cluster of VMware ESXi servers, all managed by a product called vcenter. vcenter monitors the health of all the ESXi hosts. Your VM exists on one of these ESXi hosts but any of the ESXi hosts are capable of running your VM. If vcenter detects an issue with any of the ESXi hosts, your VM is seamlessly moved from the host with the issue to one without. From your VM s perspective, there has been no change at all. Your VM will just continue to run as normal. If the ESXi host that is running your machine has a total failure, vcenter will detect this and simply restart your VM on an ESXi host without issues. In this instance you will see nothing more than a reboot. Page 3
Why virtualisation is better for your solution. Our VMware cloud environment has at least N+1 redundancy on every single component in the cluster. This includes internet connections, storage, storage networks and power. Most components are actually N+2. Because our VMware environment is clustered and protected against hardware failure in this way, your applications and services don t need to be. You will no longer need to spend money on redundant hardware that you will never need, as the environment already has this built in. Are there any limitations to virtualisation? How will my virtual server perform? In its early iterations, the overhead of virtualisation made it unsuitable for certain applications but these days are long past and major tech companies such as Microsoft and Oracle support virtual implementations for resource-hungry and complex packages such as SQL, Active directory and Exchange as standard. This does not mean there are no performance differences. Typically, a virtual machine will have a reduction in performance of about 5% in comparison with a dedicated machine of exactly the same specification. Is my data safe? Many people have concerns regarding the safety and security of cloud solutions, and the concern for a lot of people is: Is my data secure? A simple answer to this question is:- Yes, your data is as safe on our VMware cloud platform as on any dedicated server. In a VMware clustered environment, data is not stored on the ESXi host but on a central storage platform and accessed via a storage network. However, this doesn t mean that someone could simply gain access to the storage platform and access your data. There are many systems, both physical and virtual, that prevent this:- Your data is contained within a virtual hard disk; it is not just files in a folder. The only way to access the data on this disk is to mount it into a physical/virtual machine, in the same way that the only way to access a physical hard disk is to mount it into a server. To add an extra level of security, you can also encrypt a virtual hard disk, again using the same processes you would use for a physical one. There is no access to the storage platform from any virtual machine. In fact they are completely unaware of its existence. As far as the operating system of the VM is concerned, the hard disk is attached via a SCSI card. It has no concept that its own hard disk is virtual, let alone that of other servers. There is no physical connection between the storage platform and the internet. Our 10Gbe storage network exists only on a private internal range, and in order to access that range you need to be physically connected to our private management range. Our entire cluster is housed in a Tier 4 facility. This facility has 24-hour security and no one can gain access without official photographic ID (passport or driving licence) and at least 24- hours prior arrangement with the datacentre team. As you can see, your data is as secure in a VM as it is on any dedicated server. Page 4
Does virtualization offer any other features? Virtualisation allows us to approach the various challenges around hardware in brand new ways that would not be easy, or even possible, within a physical environment. Flexibility Easy upgrades and downgrades Scaling hardware requirements is difficult, particularly in a physical environment, and it requires the physical changing of components in the servers. This usually involves a lot of downtime. In a virtual environment, the hardware specification is defined by a configuration file, which can be edited extremely quickly. Adding more RAM and CPUs can be done in a matter of minutes and committed with a simple reboot of the operating system. Additional hard disk space doesn t even require a reboot and can be done on the fly (depending on your operating system). Live storage migrations VMs in our VMware cloud environment are housed on an Enterprise-level storage solution from EMC. We have 3 tiers of storage, each with its own features which better suit it to certain workflows, and each with its own costs. If your needs should change at any time, for whatever reason, we can easily move your VM between these tiers. This will change the performance characteristics of your VM instantly. This is done without the need for any downtime at all. It doesn t even require a restart. Private internal networking As well as creating virtual servers in the VMware cloud, we can also create all manner of virtual devices such as switches, firewalls and routers. Page 5
Technical Diagrams The following diagrams are to illustrate the architecture of our VMware cloud environment. They are designed to give an indication of the technologies used to create this solution. They are not, however, 100% accurate. Some devices/configurations have been purposely left out for security reasons. Storage network Key Points All of our backup links are 10Gbe. Each storage cluster has multiple 10Gbe links to the main storage core. Each server has multiple 10Gbe links to the storage core. Every component here has at least N+2 redundancy. Page 6
Internet access Key Points Every ESXi host has multiple links to the internet. Hardware redundancy is N+1. There are multiple paths to the internet. High capacity links to reduce the impact of DDOS attacks. Page 7