A Windows server can conceivably perform its tasks using the same type of storage as a workstation; that is, one or more standard hard disks connected to a standard drive interface such as Serial ATA (SATA). However, the I/O burdens of a server are different from those of a workstation; a standard storage subsystem can easily be overwhelmed by file requests from dozens or hundreds of users. In addition, standard hard disks offer no fault tolerance and are limited in their scalability.
A variety of storage technologies are better suited for server use. The process of designing a storage solution for a server depends on several factors, including the following:
– The amount of storage the server needs
– The number of users who will be accessing the server at the same time
– The sensitivity of the data to be stored on the server
– The importance of the data to the organization
The following sections examine these factors and the technologies you can choose when creating a plan for your network storage solutions.
How many servers do I need?
When is one big file server preferable to several smaller ones? This is one of the most frequently asked questions when planning a server deployment. In the past, you might have considered the advantages and disadvantages of using one server to perform several roles versus distributing the roles among several smaller servers. Today, however, the emphasis is on virtualization, which means that although you might have many VMs running different roles, they could all be running on a single large physical server.
If you are considering large physical servers or if your organization’s storage requirements are extremely large, you must also consider the inherent storage limitations of Windows Server 2012 R2.
The number of sites your enterprise network encompasses and the technologies you use to provide network communication among those sites can also affect your plans. If, for example, your organization has branch offices scattered around the world and uses relatively expensive wide area network (WAN) links to connect them, it would probably be more economical to install a server at each location than to have all your users access a single server by using the WAN links.
Within each site, the number of servers you need can depend on how often your users work with the same resources and how much fault tolerance and high availability you want to build into the system. For example, if each department in your organization typically works with its own applications and documents and rarely needs access to those of other departments, deploying individual servers to each department might be preferable. If everyone in your organization works with the same set of resources, centralized servers might be a better choice.
Estimating storage requirements
The amount of storage space you need in a server depends on a variety of factors, not just the initial requirements of your applications and users. In the case of an application server, start by allocating the amount of space needed for the application files themselves plus any other space the application needs, as recommended by the developer. If users will be storing documents on the server, then allocate a specific amount of space for each user the server will support. Then factor in the potential growth of your organization and your network, both in terms of additional users and additional space required by each user and of data files and updates to the application itself.
Using Storage Spaces
Windows Server 2012 R2 includes a disk virtualization technology called Storage Spaces, which enables a server to concatenate storage space from individual physical disks and allocate that space to create virtual disks of any size supported by the hardware.
This type of virtualization is a feature often found in SAN and network attached storage (NAS) technologies, which require a substantial investment in specialized hardware and administrative skill. Storage Spaces provides similar capabilities by using standard directattached disk drives or simple external “Just a Bunch of Disks” (JBOD) arrays.
Storage Spaces uses unallocated disk space on server drives to create storage pools. A storage pool can span multiple drives invisibly, providing an accumulated storage resource that administrators can expand or reduce as needed by adding disks to or removing them from the pool. By using the space in the pool, administrators can create virtual disks of any size.
Once created, a virtual disk behaves just like a physical disk, except that the actual bits might be stored on any number of physical drives in the system. Virtual disks can also provide fault tolerance by using the physical disks in the storage pool to hold mirrored or parity data.
After creating a virtual disk, you can create volumes on it just as you would on a physical disk. Server Manager provides the tools you need to create and manage storage pools and virtual disks and provides you with the ability to create volumes and file system shares, with some limitations.