Data & System Availability

The dynamics of applications and desktops are making them location, device and time independent. Data and systems have completely different availability requirements. They are typically stored in a datacenter that is not dynamically provisioned, although we may see that change in the near future with the upcoming cloud computing initiatives.

Data & System Availability Solutions Schema

In a modern ict infrastructure, users are working with applications. The applications use data and the data is being delivered by servers and stored and being backupped centrally. To create an overview of the data center products that are needed for datacenter solutions and to easily show the used components, we have developed the Data & System Availability solutions scheme as shown below. 

The explination of the various parts follows below. To download the whitepaper, please go to the data & system availability whitepaper.

Dynamic Datacenter

Often the dynamic datacenter is being named as ‘the Cloud'. To build and install a complete dynamic datacenter, the basic infrastructure needs to be set up accurately. Distinctive for a dynamic datacenter are the workflows to be automated as completely as possible. This way the costs are completely clarified and therefor the ROI will be directly measurable. This way the dynamic datacenter is a strategic tool and can be additional to business decissions. Key topic for a dynamisch datacenter are the management tools that ascent the datacenter from a static to a flexible and dynamic infrastructure. To show you a complete view of the Dynamic Datacenter, we have developed a special landing page. We like to refer to www.dynamischdatacenter.com (language dutch) where you can get a clear view of this datacenter.

Servers

It's servers that provide users or applications with the services they need. Services can be anything: web services, file and print services, authentication, database services, etc. In a traditional datacenter, these services are mostly executed on physical servers. These physical servers come with a lot of resources that most services don't need. They either have way too much storage, CPU power and memory, or too little. When there's not enough resources available, adding more usually adds too much of the resource, over-dimensioning them. Also, physical servers with local storage have a few disadvantages that limit their availability. If a physical server fails, the service is no longer available. A new server has to be setup, data restored and settings reconfigured. All in all a process that could take up to several days.

Storage

To cope with these availability problems, it makes sense to start with centralizing the storage. This makes it easier to allocate the right amount of storage to a service and makes it easier for the service to access it from another location, thus enhancing its availability. Centralizing storage also has some disadvantages. All storage is now on one system that becomes a new single point of failure. If it fails, the whole infrastructure fails. So this central storage has to be redundant in every aspect. It needs redundant connections, redundant switches, redundant power, redundant hard disks, redundant everything. This is what makes a Storage Area Network (SAN) more expensive than local storage.

The SAN infrastructure

Connectivity to the SAN can be divided into two main groups: Fiber Channel (FC) and Ethernet.

Where Fiber Channel provides the best performance, it's also the most expensive. A very valid question in designing a storage infrastructure therefore is 'does the customer really need that high end performance?'. The alternatives aren't really that far behind anymore. Ethernet based infrastructures are less expensive because connectivity takes place over regular Ethernet switches and regular Network Interface Cards (NICs). Not too long ago, iSCSI was the main storage protocol to be used over Ethernet. It allows LUNs to be presented as full disks to a host. With the upcoming virtualization technology however, NAS is a strong contestant now too. Whether it's NFS or CIFS, a host simply connects to a network share and stores it's data on the file system that the storage provides. This flexibility has some disadvantages though. Hosts are no longer managing the storage and proprietary file systems like VMFS don't work on it. On the other hand, a storage solution with a smart file system like NetApp's Write Anywhere File Layout (WAFL) makes it very easy, with the right toolset, to work with (consistent!) snapshots.