storage ICT
SAN to an array, had a faulty cable and faulty HBA that was causing the excess latency. A few hundred Euros spent on the problem would have averted the entire need for the new array.
Optimise the infrastructure Thirdly, the SAN is made up of may components, often many thousand, and each one of these has the potential to cause a problem. By far the best way to manage this complexity is to ‘ring fence’ an application and monitor it in real-time. For example you may have an SAP based application that is running your supply chain, this application can be isolated so you know what virtual and physical machines, switch ports, storage ports, etc. it is using. A performance threshold can then be set for this application and a window in a console created with a simple traffic light visual to show how it is performing.
This graphical view can be customised to show each department involved in supporting the application what is going on. Switch port utilisation is typically less than 10% so savings can be quickly made by load balancing traffic across them and deferring buying additional capacity until it is really needed. The main reason business critical applications are not virtualised is because performance and availability SLAs can’t be set in an environment that has a large area of ‘SAN blindness’. By monitoring the application in real-time, end- to-end across the SAN, cost efficiencies of virtualisation and private cloud technologies can be fully realised.
ensure this process goes smoothly. However it would be better to be able to model what is going to happen with an application before the migration or consolidation, particularly when virtualisation is involved. For example, you are consolidating 5 physical machines down to one and supporting 50 or more virtual machines - it is a good idea to see if it will work before you commit to moving the live application. Also, by monitoring in real time you can see everything that is going on across the SAN and alleviate any potential or real bottlenecks that cause application latency.
A typical recent example is a company (who shall remain nameless) that bought a million Euro array to improve the latency performance of their data warehouse by a couple of milliseconds. While they were waiting for delivery, they added monitoring to their infrastructure and discovered that the data warehouse, which was still attached via the
On-going performance monitoring Finally, staff managing elements of the SAN can sometimes forget why they are there – to keep the critical applications that are running the business available and performing well. When there is latency in an application there are instances of the server people blaming the switch people, the network people blaming the application owner, and everybody blaming the storage staff. Being able to improve the ‘mean time to innocence’ (or guilt) of the component or department that is causing the latency is key – and this can only be done quickly with a real-time end-to-end view.
On-going real-time monitoring of the SAN will confirm problems before they impact the users, alert you to inefficiency in capacity or I/O throughput, and allow a far better understanding of the SAN so future consolidations and migrations are performed on the elements that need improvement. Many large enterprises across the globe are now adopting real time, end-to-end application and infrastructure performance monitoring to improve their competitive advantage. Organisations that stay with a ‘black hole’ in their SAN and an ‘overprovision and hope’ policy will become less competitive on the market as their IT systems cost more and are far less efficient than their competitors.
March 2012 I
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