Store more – and better

The use of CCTV has changed significantly over the years. Traditionally, cameras were installed by private organisations to protect staff and property. Now systems are being implemented in towns and cities across the UK to help curb anti-social behaviour. It would appear that CCTV can be installed at any location for any purpose. For example, cameras are being located beside bank machines to provide added security to customers withdrawing money, and on public transport.

CCTV is also considered as a marketing tool; for example, large supermarkets can re-design the layout of a store and monitor customer traffic flow around the aisles to see whether the new design is working. While there may be concern from civil liberties groups on invasion of privacy, there is no doubt that CCTV is set to grow further.

There is a growing array of cameras to choose from – for example, colour or black and white images, fixed dome or remote control units. Although different cameras have different applications to which they are best suited, they all have the same common requirement, namely that the data captured needs to be stored.

Image capturing is only one half of the overall CCTV solution. Storing and retrieving data completes the solution – and unfortunately for many organisations, unless sufficient consideration is given to how data is stored, retrieval could be time consuming and complex or (in the worst case scenario) impossible.

Too many organisations choose to store all of their data on RAID (Redundant Array of Independent Disks) or online. And while this gives them instant access to the information, it puts the data at risk. Even when using the latest camera technology, if data is held online, then there is still a risk that the information captured will be damaged or deleted. It is therefore equally important to invest just as much consideration in choosing a storage solution as there is in choosing a camera.

Think about how the data will be used. For example, is it likely to be needed for legal purposes? If so, then it must be stored on a format which is legally admissible. Storage media such as RAID or tape are most commonly used to store CCTV images, but neither can be guaranteed against tampering – either deliberately or accidentally. Optical based media such as CDs or Magneto Optical offer WORM (Write Once Read Many) security, which means that the data held on the disk cannot be deleted or altered in any way.

Range of storage media
Most data is stored online on hard disk or RAID. This gives the user instant access to information and is most appropriate for information which is being accessed and retrieved on a continual basis. In the case of most CCTV solutions, images only need to be retrieved and reviewed if an incident has occurred and therefore not continually.

As well as not offering data security, as previously mentioned, storing data in this way means that a vast amount of a company's server is taken up through data storage.

This can not only impact the operational speed of the IT infrastructure but, if the network goes down for any reason, the data cannot be accessed until it is up and running again.

Removable storage solves the problem of storing information actually on the IT network and there is a range of storage media available for use. Tape is the most common removable storage media used by the security industry. It is relatively inexpensive, but tapes cannot be protected against wear and tear and the data is at risk. This is important, especially as the Data Protection Act requires that tapes must always be of a high quality. Tape can also be impractical as retrieval times on tape can be slower because the entire tape may have to be viewed in order to locate the appropriate images.

Optical disk technology combined with storage management software and media such as Magneto Optical, CDs and DVDs are more appropriate for security applications. The disks are housed 'near-online' in jukeboxes – from manufacturers such as Disc Storage, JVC, Pioneer or Plasmon – which means that the information is not occupying valuable 'online' network space. Storage management software operates the jukebox and intelligently stores the images captured so that they can be quickly (within seconds) located and retrieved if required.

To ensure the efficient management of the data, storage management software can help keep the amount of data actually held to a minimum. For example, all data captured can be held in a cache area for an agreed length of time. After this period, any images which have not been looked at can automatically be deleted, while images which have been reviewed, and therefore may be required for future reference, are stored for the longer term. The software can then automatically move the images to the jukebox for secure storage.

Some data management solutions, such as K-PAR's Archimedia, will provide every individual disk with its own specific file system index. This means that users can read the data stored on the disk independently of the archive network. This ensures that the information can still be located quickly, even if the network is down.

There are several different types of optical media which can be stored in the jukebox, each suiting a specific requirement.

Unless sufficient consideration is given to how data is stored, retrieval could be time consuming and complex or (in the worst case scenario) impossible

MO/WORM optical media offers a current capacity of 9.1GB and has fast access times. The media can be viewed as a magnetic disk as it has direct read/write capabilities. WORM media is the most appropriate choice for images that are required for legal admissibility.

Images stored on WORM media cannot be erased, deleted or modified in anyway.

The images are written in a format that can only be read with specialist software and are therefore the most secure. MO media provides the same benefits of hard disk storage but in a format that can be stored near online.

Using CD media to archive surveillance footage satisfies the legal requirements and, because it has the international standard (ISO9660) for writing to CD, it can be accessed by anyone with a standard PC and CD-ROM drive.

However the disadvantage of CD is that its maximum capacity is 650MB and relatively slow to access compared to the evolving DVD technologies.

DVD has the same advantages as CD, but in greater capacities – DVD is capable of holding up to 28 times more information than CD. However there are several different formats of DVD. DVD-RAM, DVD-RW and DVD+RW are all re-writeable media types and are only suitable if the images captured can be overwritten. DVD-R is a Write Once media, making it ideal for security applications where legal admissibility is an issue. The international standard for writing to DVD is UDF so all disks that are created using this format can be read by any DVD-ROM drive.

As the number of applications for CCTV security continue to grow and more cameras are installed by private and public sector organisations alike, remember that unless the images captured can be easily retrieved and are of sufficiently high quality, the whole exercise may become a costly waste.