As we initially discussed two weeks ago, the private cloud can be a bit difficult to clearly define and differentiate from the traditional data centers. First of all, to make sure that we are not being 'cloud washed' (i.e. sold as cloud something that is not), let's review the key attributes we need to look for when analysing an private cloud offering.
Private Cloud - General Description
It is also called an internal cloud or enterprise cloud. It offers functionality "as a service". It is fully managed by a cloud provider but is deployed over a company intranet or hosted datacenter. It is meant to provide most of the benefits of a public cloud - scalability, ease of access and use - while improving security and availability from a speed and guaranteed up-time perspectives. In general, a private cloud shares few, if any, resources with other organizations.
Private Cloud - Key Attributes
1) Location - In principle, the servers and other infrastructure that make the private cloud can be located anywhere but, normally, it will be housed within the company's premises. This often makes managers more comfortable regarding security and compliance.
2) Resources - In general, the company itself will provide the hardware infrastructure (servers and connectivity) but it will be an external cloud service provider that will facilitate everything else - management of the infrastructure and the operating system, security, S/W updates... This model will allow a company to transfer many of the day-to-day responsibilities of its IT department to an external team, thus allowing it's own internal resources to focus on other types of development that can provide more value added to the company.
3) Linearly scalable - There should be no limit to the amount of capacity a company or user can access. This does not mean that the company will not have to worry about growing the infrastructure when the servers go over capacity - at the end of the day, the hardware infrastructure is its responsibility - but it does mean that this process will be totally transparent to the users and, in principle, will be done automatically by the service provider. So, for example, any server additions, server upgrades or data migrations should happen in the background, managed by the cloud provider and with no impact on daily activities.
4) Virtualization - A private cloud will mainly use two types of virtualization:
4.1) Storage virtualization - Pooling of physical storage from multiple network storage devices into what appears to be a single storage device that is managed from a central console.
4.2) Server virtualization - Pooling of infrastructure resources - such as physical servers, processors and operating systems - into what appears to be a single source of computing power. This reduces the level of complexity the user needs to deal with when interacting with the system while increasing the utilization of the infrastructure.
The creation of this virtual environment is what allows the scalability and transparency discussed in paragraph 3. Virtualization is key for all cloud types but it is very important to make sure that it is being used by the private cloud provider that you are using because, otherwise, you are not 'buying' a private cloud but rather a conventional data center.
5) Chargeback and Multi-Tenancy - These capabilities are not always required by the client but the provider should be able to provide the service.
5.1) Chargeback or Showback - This capability allows each department or division's transactions and storage use to be tracked so IT administrators can see where the bulk of the storage burden is. If fees are charged based on usage, this service is called chargeback, otherwise it is called showback.
5.2) Multi-Tenancy - It is required when customers share an application or resource and each customer's resources and data can't be available / visible to other tenants on the cloud. Depending on the way the company is setup, this may not be a requirement but, when data usage needs to be clearly limited and restricted, this will be a key attribute.
Private Cloud - Benefits
The main benefits will be around control / security, availability and speed of access.
1) Control / Security - Only your company is accessing the data and programs in the private cloud so, the perception is that the information and resources are safer. I specifically say 'the perception' because public clouds normally have very strong security and protection capabilities and, if well ran, may prove safer than any firewalls and system barriers a company may put in place.
Another benefit from a control perspective is that, in highly regulated industries, such as banking or insurance, it may be very important to always know the exact physical location of your data. For example, for many European institutions, customer data can only be kept within the borders of the European Union and, in some cases, of the specific country where the customer resides. Even if your agreement with the service provider of the public cloud clearly states possible locations where your data may reside, where your local regulator to request proof, it could be extremely difficult to demonstrate that this clause has been respected at all times.
2) Availability - Cloud services are 'everywhere' these days but the industry is still in its infancy. As result, contractual agreements are still being developed and refined and, at the moment, it is easy to see that there is no established standard or formal agreement around the contractual minimum availability of the system. That is, it is not clear what will be covered by whom if the service were to go down for 1 hour, 1 day or 1 week.
If you have full control of the system, problems may still arise, but you will be much more able to determine the likelihood of an event and also to avoid it and fix it should an issue arise.
3) Speed of Access - A public cloud is, by definition, part of the Internet. The key benefit of the Internet is accessibility and reach, not necessarily performance or speed. If a company needs to read/write large amounts of data very quickly or needs to run applications with large bandwidth requirements, the Internet may not provide the performance required where the private cloud can be built and managed to ensure
Private Cloud - Drawbacks
The main drawback will be around scalability since the company is still responsible for setting-up, maintaining and growing the infrastructure as necessary.
After reviewing public and private clouds, the two ends of the spectrum, next week we will focus on hybrid clouds - definition and pros & cons. We will also provide a simple table comparing each of the options around cloud implementation. These three blogs together will give you a good view and understanding of the alternatives and their corresponding benefits.
1) The Ultimate Guide to Cloud Computing - MagBook, Cloud Pro - www.magbooks.com - @DennisMagBooks
2) IDC Blog
4) PC Mag series of articles titled 'What is Cloud Computing?'