Mind the store!

According to a recent report from BBC Online, the average citizen is caught on CCTV cameras 300 times a day and surveillance technology is constantly evolving. However, regardless of how the images are being used, too many companies are installing cameras without thinking about the data storage requirements behind them. Sufficient consideration is rarely given to the security and integrity of the images once they are captured Worse case scenario
Unless the data is stored correctly, the surveillance system may at best be inefficient and at worst com-pletely worthless. For example, imagine the conseq-uences if, when the time comes to investigate an incident, the specific images cannot be found.

Images captured by surveillance cameras that are not stored correctly are vulnerable. Any data that has been written on re-writeable media can be overwritten or permanently erased – either accidentally or purposefully. Or the information could become corrupted, for example deliberately altered or damaged through general wear and tear of the storage media.

Add to this the issue of legal admissibility. If the footage is likely to be needed in court it is important to remember that the principle of the UK justice system is based on the concept of 'beyond reasonable doubt.' If for any reason the footage cannot clearly demonstrate the offence taking place at the specified time, or that the data has not been recorded on legally admissible media – for example, Write-once-CD, DVD or WORM (Write-Once-Read-Many) – then there is a far greater chance that the case will be thrown out of court.

It is also important to ensure that there is adequate storage capacity available. Imagine the sheer frustration if the camera footage runs out at the exact moment the perpetrators are in action.

Images of value
Organisations therefore need to put as much emphasis on storing the images as they do on capturing them, in order to ensure that images captured by their surveillance cameras provide as much value as other aspects of intellectual data in their organisation.

As with all data, it is important to have a thorough understanding of how it will be used in order to make the appropriate decision on how it should be stored. Questions that need to be considered include: Will the footage be required in court? Does the footage need to be kept indefinitely or can it be overwritten after a specific period of time? How quickly are the images likely to be retrieved? Once it is clear how the data captured will be used, then the different storage media on the market can be assessed and the most appropriate solution chosen.

Hard disk and RAID (Redundant Array of Independent Disk) technology can provide organisations with very fast access to data but it is at risk of becoming corrupt or deleted.

Time consuming
Tape is one of the most widely known forms of data storage and although it is one of the most cost effective storage media available, it is not ideal for surveillance images. Locating and retrieving a specific piece of footage can be a time consuming process as the data cannot be directly accessed and tape is prone to wear and tear, particularly if it is re-used, making it unsuitable for legal or archival purposes.

Optical disk technology combined with storage management software and media such as Magneto Optical (MO), CDs and DVDs are often more appropriate. The concept of storage management software using optical disk utilises hard disk/RAID for the immediate storing and accessing of data, and optical disk for near online storage. This means that all data is stored securely but is still accessible. The disks should be stored in optical jukeboxes and managed using data management software. The software will intelligently store the images and quickly (within seconds) locate them if they need to be accessed. Some data management solutions, such as K-PAR's Archimedia, ensure that every individual disk has 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.

Optical media
There are several different types of optical media and each suit a specific requirement.

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 you with the 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.

Different DVD formats
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-writable 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.

Unfortunately there is no guarantee that installing surveillance cameras will reduce crime levels. But by having a clearer understanding of how the images captured will be used, organisations will be better placed to invest in storage solutions which will help ease the process of image retrieval should an incident occur.