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Workgroup Storage Solutions

Dec 1, 2004 12:00 PM, By Bob Turner

Is now the time to invest in shared RAID storage?

Shared storage may finally be ready to be considered for the majority of postproduction facilities — whether the single operator boutique or the multiple-suite facility. New open metadata standards, such as AAF and MXF, and the fact that manufacturers are finally achieving compatibility with those standards, have caused many to take a second look at alternatives to “sneakernet.” Also, more importantly than shared metadata, have come new storage technologies capable of much higher bandwidth performance and with significantly reduced costs.

Avid Unity MediaNetwork has been offering shared storage since the spring of 1999 for the higher-end postproduction industry. Avid Unity offers project- and bin-based media access rather than volume access, ease-of-use intuitiveness (the server appears as a network drive icon on the desktop), security to prevent unauthorized access to files, “elasticized” storage volumes, AAF compliance, and realtime performance.

Avid Unity was designed for a post facility. It is expandable, reliable (with redundancy), cross-platform, and works with any digital media. Avid Unity also offers productivity tool options, such as Avid DMS ProEncode, Avid Media Station XL, Avid Unity MediaManager, Avid Unity MediaManager Select, and Avid Unity TransferManager.

In many ways, the best features of the Avid Unity have not been duplicated by any other manufacturer. On the other hand, the cost is considered pricey by many, and some aspects are designed for Avid products only. There also have been comments about the product's performance — especially when considering uncompressed high-definition video. Many of those issues have been compensated for with Avid's NLxHD codec.

(Note: Avid Unity shared storage is also available in a lower-cost version with many of the features of the Unity MediaNetwork. Avid Unity LANshare EX starts at $42,500, with support for up to 20 Ethernet-based clients and nearly 3TB of storage.)

This month's column is the first of a two-part series. In this column, I plan to analyze benefits of workgroup storage technology and then look at the features you should consider. I will also explain the differences between a storage area network (SAN) and network attached storage (NAS). In part two next month, I will look at a few of the solutions introduced this past year.

Why workgroup postproduction?

The first question that needs to be answered is why would you choose this type of storage? I will answer with a few examples of the benefits you can derive from a workgroup storage solution.

One benefit is better use of a staff's specialized skill sets. For example, one person at a facility may be best at effects compositing or audio mix-to-pix while others are best at offline and others finishing. Shared storage for media and metadata is the most efficient workflow.

Another benefit of workgroup storage is cost effectiveness. Rather than allocating storage for each workstation, you can have a centralized storage solution that allows constant re-assignment of storage assets as needed.

Also, it's helpful in a multiple suite facility to have a single location for storage maintenance, media management, and administration. The ability to move from suite to suite without a cumbersome process of moving media and metadata can also be beneficial.

Choosing a system

Lesley Glorioso, a product marketing manager for Avid, recently gave a presentation entitled “The Benefits of Better Storage.” She explained that storage is an expensive component, but is the heart of your facility.

Glorioso recommends that you look for a system that:

• Offers both quality and reliability with a good warranty;
• Scales in capacity and performance;
• Is of a trusted brand that provides proven service and support with a good supply of spare parts;
• Security that can prevent unauthorized access to files and metadata;
• Has the ability to sort, catalogue, search, and easily find and retrieve data;
• Delivers performance acceptable both now and in the foreseeable future.

Other factors to consider include cost (per protected gigabyte) and security.

When evaluating a system, you should ask yourself the following:

• How many workstations will be connected to shared storage?
• What operating systems will those workstations use, and is the storage system being considered fully compatible with your workstations, operating systems, and applications?
• What audio and video files (and video resolutions and formats) will you be working with?
• Analyze the process required to work on a collaborative project. How cumbersome is the process? Focus on the ability to share timeline metadata and update a timeline two or more editors are working on.
• How much storage do you need after taking into account RAID redundancy?
• Since it is a fact that every hard disk will eventually fail, what is the most cost-effective way to protect yourself from disaster? Can you afford downtime during repair, and can your media be replaced easily?
• How many projects do you need online at any given moment?
• How fast is your business growing? How many workstations or what storage requirements will you have by the time you pay off your present system? Will it scale to your future needs?
• What engineering or IT support do you have available? What additional support do you require or expect from the manufacturer?
• Do you need to access the Internet or encode projects for the Web or DVDs? Do you need rendering nodes for animation or complex composites?
• What archiving methodology will work best for your needs and will it integrate with your solution?
• Will the metadata (extensive edit decision lists and library information) be compatible across applications?

SAN vs. NAS

When examining workgroup storage options, one of the most confusing things is choosing between a SAN or a NAS.

A NAS is a server with attached or integrated storage and central management of volumes and security. A NAS uses a network protocol such as TCP-IP over Ethernet. NAS was designed for consolidation of network storage from lots of hard drives on different platforms across a department or building to a single protected and centralized repository.

In a NAS, the server processor itself passes all the data to the users from volumes that are formatted on the server and only locally available to the server, so the central motherboard and CPU can be a single failure point and also a bottleneck in some configurations.

Very fast motherboards and CPUs will allow for a decent bandwidth, but overall throughput will always be less scalable. Also, it is important to make sure that the applications you intend to use on a NAS are compatible with network-attached volumes.

What NAS does give you is the best security because the volumes, storage, and permissions are all included in a single point. NAS also allows greater availability to other ancillary systems on the network, such as GFX and effects stations without another layer of re-share.

A traditional SAN solution utilizes a dedicated and unique link to the storage from a hardware controller using a large block protocol designed for large transfers of data. The biggest benefit of a SAN is dedicated bandwidth through the hardware controller that removes the client CPU from the job of processing all the data coming into the system. For most applications, Fibre Channel will be the choice for SAN solutions because of the protocol's ability to support multiple initiators and the lengthy cable runs (up to 300 meters for multi-mode fiber).

Both SAN and NAS have the ability to share storage capacity. NAS solutions, by definition, include a server that provides file-level sharing capability, which offers increased benefit for collaborative editing.

SAN architectures

There are three kinds of SAN architectures, all differing in complexity and performance. The first is the most simple, the “storage-direct” SAN, where “dumb” storage sits on the back of a switch or hub that also connects to the users. This is a fast solution because there's nothing between the users and the storage. The disadvantage is lack of security when users are in charge of their own access management. There is no central location that can be locked and secured, and in some configurations all the users see all the raw drives.

The second architecture is the “server-assisted” solution (e.g., Unity, ADIC, and Apple Xsan). This system incorporates a metadata server that processes all requests from users. Since the server just processes the requests and not throughput of the actual data, this architecture is relatively fast. There may be a point at which the server can become a bottleneck if a very high bandwidth is applied or there is a large user count.

This solution may be more complex, may have more points of failure, and may be harder to integrate and troubleshoot. However, it is secure, and it allows for a distributed file system to be used for crossplatform access, file-level sharing over Fibre Channel (in some cases), and virtual resizable volumes.

The final and newest SAN architecture takes advantage of the new technology of 4GB multi-port fiber HBAs and low-cost, high-performance SATA drives.

The Terrablock system from Facilis Technology is an example of this “server-direct” architecture. In this design, there is a central server for a single point of administration, but the server itself does not format the volumes, nor is the server responsible for re-sharing volumes to users.

The virtual volumes are only exposed to the fiber-connected clients, so the server itself does not impede the throughput of the system. The virtual-volume system allows for project-based volumes to be created and deleted without affecting the remainder of the storage pool.

In the Terrablock example, up to 250 of these virtual volumes can be formatted individually as Mac or Windows units, and have compatibility with almost any application due to appearing as local SCSI storage to the OS. The solution is secure, since volume access is managed by the central server, where administration can also occur.

The biggest benefit of a SAN is dedicated bandwidth through the hardware controller that removes the client CPU from the job of processing all the data coming into the system.

In part two, I plan to look at a few of the new systems introduced this year and examine how each is unique. My intent is to provide you with product examples whose features you can evaluate to compare with the many solutions available.

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© 2008 Penton Media, Inc.