Ask the experts Ultra-slow motion in live broadcast by Keith Warburton, Global Distribution W hat is the most important thing to consider when choosing storage for content creation applications? Sec of bandwidth, as well as a higher load on the host and hard disks. Once you have established the capture device and the codec that the data will be acquired in, it is an easy process to extrapolate from the MB/Sec figure to the total storage required. For example, ten hours of ProResHQ 442 would require a storage capacity of approximately 1.12TB. Always keep in mind that a hard disk storage system, no matter what manufacture, will suffer from performance degradation if the storage volume is filled to near capacity. It is also important to make sure that the storage device you choose is capable of sustaining the data rate and I/O required for your chosen codec as failure to do so will lead to a more time consuming editing process or, at worst, the inability to edit the material. There are three key factors that determine the performance of the overall system: the power of the edit workstation, namely the CPU and RAM; the interface to the storage system; and the processing power of the storage system itself, including the number of disks in the system. The single most important aspect to consider when choosing a storage device for content creation is workflow. It is critical to have made a decision with regards to the capture device, the video format to be used and how the finished project will be delivered. This will in turn help you decide on the host interface for the storage system, the required storage capacity, whether you need a RAID protected device or not, if you need to hold content for an extended period of time, and what the best medium is to archive the content on. use. The exception to this is the new Thunderbolt interface that provides a staggering 10Gb/sec host interface creating 500-800MB/sec desktop RAIDs that are currently available. As a general rule of thumb the plug and play connectivity types are great for codecs with low data rate requirements and direct attached environments, one storage device, one workstation (or laptop), and a single editor. Connectivity such as Fibre Channel (FC) is generally deployed in larger collaborative workflows with multiple workstations accessing a large amount of centralised storage, which is known as a Storage Area Network (SAN). A note of caution with regards to interface; just because the interface is capable of making a high performance connection does not mean that the storage device will be capable of providing that amount of performance to the host. The performance of a solution is highly dependent on the number of hard disks in the system. Note to people thinking that a single HDD with a Thunderbolt interface will be the answer to all! NB do not confuse your megabytes (MB) and megabits (Mb), a megabit is 1/8 of a megabyte and the same goes for gigabytes (GB) and gigabits (Gb)! How do I calculate the capacity and performance I need from my storage? There is a wide range of capture devices capable of acquiring data at HD resolutions such as consumer camcorders, DSLR cameras, HD video cameras and 35mm Digital Cinema Cameras. All of these devices use a codec (Compression / Decompression) which is simply an algorithm that shrinks large movie files to a more manageable size, and also makes them playable on a computer. For example, an uncompressed 1080i 10-bit file would have a data rate of 165MB/ sec, which is difficult to work with. A codec such as Apple ProRes422 HQ is only 32MB/Sec, REDCODE 42 is 12MB/Sec and AVCHD is 3MB/Sec, reducing both performance and storage requirements. It is also important to consider the number of layers of video being worked with simultaneously. Two layers of ProRes422HQ requires 64MB/ What host interface do I need on the storage? There is a wide range of interfaces on the market from the mass market FireWire 800 (800Mb/sec), USB 2.0 (480Mb/sec), eSATA (3Gb/sec) and the new Thunderbolt (10Gb/sec) connections that provide `plug and play' functionality, to enterprise connectivity such as 8Gb Fibre Channel (8Gb/ sec) and 6Gb SAS - Serial Attached SCSI (24Gb/sec) that require a host interface adapter for computers. In general the plug and play interfaces offer a lower performance but are easier to What is RAID and do I need it? RAID is the "Redundant Array of Independent (or Inexpensive) Disks". If you have been using hard disks for any length of time then I would almost certainly think that you would have had experience of a hard drive failure and as a result might have even lost data. One of the benefits of RAID is that it can be used to protect data. 50 | TV-BAY MAGAZINE