SAN storage

Virtualization of data storage has changed the way editors and technical engineers access shared data. The method of spanning multiple physical components to present a single pool of space is affecting the way broadcast facilities allocate storage resources. This article will explain virtual volumes as they relate to SANs in broadcast environments.

Before investing in a storage network, you'll have to evaluate many aspects, including: connectivity, filesystem support, device management and usability. The reason behind there being so many storage products on the market is because there are so many different types of facilities. When comparing all of the available offerings for your environment, your specific workflow should be the determining factor.

Why virtual volume?

When choosing a SAN, a couple of key factors to consider are: 1) the availability of the storage pool and 2) compatibility of the file system. As the workload or equipment changes in your facility (as it always will), making a poor decision about a SAN feature set will come back to haunt you. Having a dynamically scalable and widely compatible environment will keep your facility working into the future when new applications, operating systems and rapid expansion add additional load to your network. Virtualized storage offers this through the ability to add and delete volumes, expand volumes, and change access permissions to any portion of the network, even during peak production hours.

Virtual volumes can span a large number of drives regardless of the volume size, so very small portions of the SAN can be allocated for smaller projects without sacrificing performance. At any time, more storage can be allocated to a particular workstation or user, and data existing on this allocation may be shared among several workstations. Users can take advantage of project-based volumes that are managed individually, as opposed to large chunks of storage with a single file system that holds multiple projects. This can complicate the media management of the facility and cost valuable time when the deadline looms. Virtual volumes can also ease maintenance requirements, eliminating the need for defragmentation (optimizing) and allowing the users to completely fill the SAN to 100 percent without any loss of performance. Up to 25 percent of a traditional drive array will underperform based on linear (non-virtualized) write patterns.

Standard RAID storage holds users to pre-determined partitioning according to stripe sets within the group of drives. The stripe size will be determined by the number of hard drives needed to achieve adequate performance. The partitioning of the LUN (device logical unit number) may be static, leaving little ability to re-allocate or expand the partition available for a certain project down the road. These systems will often have to be destructively reconfigured in order to make changes to stripe sets, or when expanding capacity.

When configuring file systems on virtual volumes, administrators can take advantage of native OS formatting of NTFS, HFS+ (Mac OS Extended), XFS or EXT3, or choose a custom file system that allows for write access from multiple workstations simultaneously, on multiple operating systems. These shared file systems are used to enhance collaboration for facilities working with shared projects. Some shared file systems can be customized to provide emulation modes for workstations that benefit from increased functionality on proprietary storage systems. Certain products, like TerraBlock from Facilis Technology, offer both native OS formatting and shared file system operation concurrently, to deliver the highest performance and total collaboration.

So, why doesn't everyone do this? Virtualization of individual hard drives into a pool of storage is a difficult task. The qualification of bandwidth, data protection and data integrity are all vitally important. However, the result of this technology is simple administration and maintenance with greater flexibility when compared to more traditional server-based or direct-attached SAN systems.

Also, a lot of old technology is out there. It's easier for a storage company to re-brand older software packages as new for the purpose of creating a “turnkey” solution. While these older SAN software packages are field-tested, they lack features and functionality needed by today's creative facilities. Dated SAN technology will struggle to keep up with changes in operating systems and platforms. Client-based (direct-attached) software solutions keep end users from adding upgrades to workstations that could change the supported configuration, since clients are in essence “running” the SAN. Also, more networking infrastructure is required to satisfy metadata paths.

Workflow features

Moving past how virtual volumes can ease administrative workload by allowing for dynamic allocation, what other benefits are there? For one, as much or as little of the SAN is available to any client without involving complex network permissions. The workgroup stays manageable through per-user login to access unique permissions. This allows the administrative control over the amount of active data available to the end user, while always having additional volumes available if needed.

Financial features

Centralizing storage assets will reduce costs, eliminating the need for local storage. Virtual volume storage may also decrease overall storage deployment due to more efficient allocation. Some SAN solutions require individual workstation licensing, which can bump up total cost of ownership. (Not only can there be hidden initial costs, there are per-seat/year-on-year expenses as well.) Virtual volume systems like TerraBlock require no per-seat license, so there is no software package to purchase when adding fiber-channel or Ethernet seats to the environment. In addition, since this virtual volume SAN can be used across multiple OS versions concurrently, upgrading client workstations does not have to be an all-or-nothing proposition, saving thousands in incremental costs.

In addition to the cost of physical resources, a virtual volume SAN provides savings in hourly labor and increases satisfaction among your employees. Since a central, shared storage system allows for migration of projects between and among similarly engineered workstations, scheduling becomes easier to manage. Downtime in a particular room, due to required upgrades or a work-station hardware failure, won't derail a project. The features of project-based storage for media management make backup of critical data off the SAN easy, with the full availability of the storage volumes across the network.


Many facilities worldwide have found uses for virtual volume storage that go well beyond the original specification. A robust SAN can be repurposed into other workflows, new and better editorial and content creation workstations, and even the central storage for an entire end-to-end production workflow. The chief engineer faced with the task of creating a custom storage network will always turn to a virtual-volume SAN, due to the ability to create a sustainable network that will future-proof his or her facility in an ever-changing environment.

James McKenna is vice president of Facilis Technology.