Storage Virtualization

Server virtualization from VMware, Citrix and Microsoft has taken the business world by storm, allowing organizations to consolidate tens or hundreds of hardware servers into one or a few hardware servers containing multiple virtual servers. The results are much lower hardware costs, more efficient use of server resources, power and cooling savings, flexibility and agility.

Virtualizing existing Hardware and convert it into files that run side by side in one big server solves a lot of problems. Reducing costs like power consumption, saving money due to reduced amount of unique systems, much better usage of given capacities are the main interests.

The main issue to solve is where to store the data as both virtualization and virtual servers must store their data somewhere. Organizations of all sizes today are seeing their storage needs almost double or even triple every year as they digitize business processes, expand their Web presence, embrace disk hungry audio and video applications, and retain files and data longer to comply with regulations and legal pressures. Unfortunately, in the physical world, storage is usually tied to a single server or application. While there are many different types of virtualization solutions, the concept of storage for virtualization is very simple and similar to that of server virtualization. This abstracts the logical aspect of storage from the physical, allowing you to pool and share large quantities of storage among several applications and servers, regardless of the physical hardware that lies underneath. It masks the underlying complexities of individual storage device configuration and management and puts all provisioning, management and allocation under a single virtualization management interface. The result is a single logical storage pool that you can slice, dice and allocate to applications at will.

Storage Technology

NAS, Network Attached Storage, is file-level computer data storage connected to a computer network providing data access to a heterogeneous group of clients. NAS not only operates as a file server, but is specialized for this task. “File level” means that a NAS receives data in form of files send by a client in the network. Therefore NAS provides both storage capacity and an internal file system to store the received files. The data traffic between the clients and the NAS is based on protocols like SMB/CIFS (Server Message Block/Common Internet File System), FTP (File Transfer Protocol) and/or NFS (Network File System).

The other major technology in storing data is a SAN, Storage Area Network. SAN is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage devices such as disk arrays accessible to servers so that the devices appear like locally attached devices to the operating system.

A SAN typically has its storage device that is generally not accessible through the local area network by other devices, which is in general the opposite behavior of a NAS. SANs are usually using iSCSI, an acronym for Internet Small Computer System Interface, an Internet Protocol (IP)-based storage networking standard for linking data storage facilities.

This protocol allows clients (called initiators) to send commands to iSCSI storage devices (targets) on remote servers. This allows organizations to consolidate storage into data center storage arrays while providing hosts (such as database and web servers) with the illusion of locally attached disks.

NAS vs. SAN

 

Virtualization can be undertaken with either network attached storage or a storage area network or both, but it’s usually not a good idea to combine the two in a virtualization strategy as the performance differences between NAS and SAN are pretty significant. Some solutions work with server attached storage as well. Most organizations virtualize one or the other and SANs usually win because of their performance advantages. However a small business that relies mostly on NAS can use NAS based virtualization quite successfully.

As written above there is a big difference between NAS and SAN regarding their individual way of operation. The NAS part is file orientated, the SAN part is block-level orientated. Thus could lead to the misunderstanding that there is no link between both worlds.

Buffalo’s TeraStation™ 4000, 5000 and 7000 series support both NAS and iSCSI on one and the same machine. With the help of a so called LVM, Logical Volume Manager, the user can provide a part of the whole capacity for NAS and workgroup purpose, another part can be dedicated as so called LUN, Logical Unit Number, and iSCSI capacity for virtualization environment.

Simultaneous Use as a NAS Server and iSCSI Target

Create NAS and iSCSI volumes on a single RAID array. Supports simultaneous usage of NAS and iSCSI in one device.

Advantages

  • TeraStation unit can be placed virtually anywhere in the office
  • Low TCO as there is a centralized storage for both environments
  • Easy-to-use as everything can be handled even without a graduate in informatics