Myths
Myths about Virtualising Exchange, Citrix and SQL on VMware ESX
Overview
You may have heard about the potential problems with virtualising Microsoft Exchange, Microsoft SQL and Citrix Presentation servers. Is it all true? Or misinformed information from the uninformed?
One thing we should always remember about any deployment is planning. The need to follow best practices on deployment of Exchange, SQL and Citrix don’t go away when you deploy these applications into a virtual machine. The proper placement of logs and databases are always important and should be planned out before you do the deployment.
Microsoft Exchange Server
Today’s multi-core and high memory capacity servers can cope perfectly with hosting multiple machines on a single host. Exchange Server solutions are typically constructed with a number of server computers performing differing roles, for example transport servers, access servers, mailbox servers etc. Each server role will have a resource workload profile, e.g. the workload profile of a mailbox server will have significant disk IOPS requirements, whereas a transport server would likely have a higher peak CPU requirement and less disk IOPS. Virtualising Exchange is about understanding workloads and provisioning the correct resources for the workload. Taupo examine workloads and right-size virtual machines. Further, we construct a virtual infrastructure cluster of VMware hosts to provide high availability and the opportunity to load balance and ensure VMs receive the resources they are entitled to. Exchange Server has been proven to run with 16,000 mailboxes on 1 server, a feat that could not have been achieved without using virtualisation. Maximise your availability without the complexity of Microsoft clustering using VMware technologies such as DRS and HA. As with all our projects, Taupo take the time to understand Exchange workloads and their resource (CPU, memory, disk & network) consumption patterns, designing the most appropriate virtual infrastructure to match the workload. Microsoft SQL Server Understanding workloads is critical when understanding virtualisation using any vendors product. Taupo have successfully virtualised SQL in a large number of clients worldwide, by following a mature robust process to ensure we understand the SQL workload. In the majority of cases, the database workload can be virtualised perfectly using a design methodology that ensures disk workload separation and guarantees of resource to meet SLA. There are situations where SQL has not been virtualised due to conflicting design goals, e.g. an OLTP cluster delivering essential in-line processing for a website whilst simultaneously achieving the highest level of VM/host density possible. SQL Server on VMware technology makes it possible to ensure high levels of availability for SQL Server without the cost of identical clustered servers. Microsoft clustering maintenance brings complexity when hardware or software components are patched or upgraded. The SQL in a VM approach gives you a viable alternative to expensive 3rd-party failover and clustering solutions. But what about Microsoft clusters? What if you still need to use them? Well, VMware ESX can handle Microsoft clustering too! Within a well constructed VM environment, Taupo can deploy Microsoft Clusters in VMs, where each node of the cluster exists as a VM on disparate ESX hosts. Citrix Firstly, it should be stated that Citrix Presentation Server (XenApp) can be deployed as a virtual machine on VMware ESX Server! Where confusion over this product has arisen is around how best to run Citrix in a VM. A presentation server in the physical world traditionally has been a server that we throw RAM and CPU resource at to scale to support more users. In the virtual world, there is a better way to support such workloads, based upon scaling out and not up, in other words, a Citrix farm of 4 physical servers, could be virtualised as say 6 Citrix VMs. The Citrix workload can be virtualised in several ways and over a number of ESX hosts, thereby allowing them to benefit from VM load balancing where we can proactively move workloads off a host to a less busy host to enable Citrix to get the most from the hardware. Such optimisations yield incredible performance gains. This again highlights that having virtualisation experience and understanding of workload is key to the success of your project. This is why we do not simply perform P2V operations; we use our experience of workloads to best size and deploy the VMs which will work for your organisation. For further information please call 0845 094 3366 or click here.