ISG (Internet Services Group) has for the last six years been managing Esri UK's hosting and web services both for internal and external clients. This was supported through internal and third party hosting suppliers.
The cloud offered a number of differences (I would not use the term 'advantages') over traditional on-premise hosting.
The on-going debate between on-premise and cloud solutions comes down to specific details and requirements within each organisation. The decision to go with one or the other solution should be made only after reviewing each organisation’s unique situation. Cloud computing offers a lot but it should not be regarded as the magic bullet.
ISG started off with an on-premise model but over time migrated towards a cloud-computing infrastructure as provided by Amazon Web Services (AWS) and taking advantage of the utility pricing model where one only pays for what one uses. When a server or resource is not required, it is turned off saving money both in terms of management and power. There is no need to pay for excessive capacity.
AWS had been working with Esri Inc to create ArcGIS Server Amazon Machines Images (AMI) - which are pre-created ArcGIS Server 10.0 virtual machines running on the AWS cloud. ISG have been using these AMIs, editing and reconfiguring them for our specific requirements and commissioning them for use. For ISG, the cloud has meant that managing hardware and software with a small team, isn't such a time consuming task anymore. Gone are the days where one needs to travel down to our hosting centre to change disks. The headache of hardware upgrades are now a thing of the past as AWS continues to add and maintain the underlying hardware.
For Esri UK the PROS and CONS of a Cloud model of service provisioning include:
•Lower Total Cost of Ownership (TCO) - certainly, the cost to the business of setting up a hosted service has dropped dramatically. In the past, even before the first user - a hosted solution would have cost upwards of £1,000s to setup. Now, a few days of work and the service is usually ready.
•Scalable performance to fit business’s needs. If a service has seasonal peaks (i.e. an online conveyancing service or a charity web site) then the ability for the resources to expand in terms of size and power as usage demands it becomes a big plus for us. Resources can be added almost instantly. In the past, one had to purchase extra hardware which would become redundant after the initial peak requirement. The cloud grows as big and as quickly as demand requires or conversely, can shrink down to a minimum. Saving in cost all round.
•Reduce upfront costs on hardware and software means that ISG does not need to spend days working up estimates on hardware costs and maintenance payments.
•Higher server availability and recovery. If one server fails, it is automatically picked up on another server assuming a copy of it was made. Usually, this new server can be online within minutes. Even higher availability can be provided if the solution involves clustering and load balancing.
•Utility based. With a cloud solution we will only pay for the amount of server resource we need and pay for them on a monthly basis, like electricity.
•Bandwidth costs could potentially be very high if user numbers prove incorrect from estimates.
•Not all software programs can be moved into the cloud.
•Depending on the size of the client, it may not be a great price difference between cloud and on-premise.
•Security can be a concern. If a service or a client has specific security requirements, it may not be able to move to a cloud-based solution.
•Downtime. One is completely dependent on the Internet and service provider. If the Internet is down, service could be offline. The risk is of failure is there but it is borne by Amazon Web Services[i] rather than ourselves.
•Continuous cost, after the initial pain of capital expenditure - the cost of running an on-premise recedes to a background cost of staff salary and core infrastructure costs (power and light); it becomes an asset that depreciates in value. With the cloud, one can have a variable and continuous cost that may be difficult to predict. This can cause issues with budget forecasts and estimates for the business.
•Even for simple demonstrations, testing etc - one still has to pay. One doesn't have an 'old' machine handy to load up a test environment.
Since there are several PROS and CONS to hosted models and on-premise models, ISG has found a compromise in a hybrid solution. A hybrid solution for ISG means that some of our resources are still on-premise (a combination of physical, virtual and internal cloud resources) these are used for testing, demonstrations and for specific clients. Our production/live services are now cloud-based giving us the best of both worlds.
A lot of other areas need to be discussed such as the relevant performance of disk I/O between cloud resources as opposed to a physical on-premise resource. Security is another large area of concern as well as the necessary changes in one's working habits.
I guess that's for another time.