Security Beyond The Camera

Installing a security system of any kind requires planning. Planning to consider location and construction factors, planning to determine outputs and planning to govern day-to-day operation. But despite good planning, where some systems still come unstuck is deeper down at the 'data' level. Planning to create the safest place for your data is paramount if your system is to function effectively – and ensuring that the data's 'integrity' is preserved is key to this.

Data integrity is all about knowing whether the internal 'health' of your recorded media is sound, whatever format that media takes. We anticipate that over two thirds of the security industry is still reliant on VHS video storage for CCTV applications. Data integrity is tough to measure here as these tapes inherently degrade on a per-use basis.

We know that VHS tapes are susceptible to time-based degradation as well as damage from physical shocks and environmental factors such as heat and water. They also suffer from lack of automation – it's far harder to automate a VHS system as it usually requires a human to insert and remove tapes, which in itself introduces yet another layer of potential error. So although the tapes themselves are relatively cheap, the long term TCO (total cost of ownership) can potentially be a lot higher.

Perhaps the reason that VHS tapes have remained ubiquitous is that there is still an inherent mistrust of hard drive reliability – but in fact, properly housed in a secure drive enclosure, hard drives offer a superior price per gigabyte storage option with high degrees of reliability in a smaller form for CCTV control room locations where space is often at a premium.

Data capture on hard disk is of course also still open to damage from heat and water. But the dan-gers are more manageable here and the IT enviro-nment that can be built to support these systems, if well planned, can be considerably more robust.

Demand for high spec storage
Before looking at how the danger factors for hard disks in CCTV and other security environments manifest themselves, it's worth considering how the demand in this sector is likely to develop.

Today there are literally hundreds of digital video recorder manufacturers offering higher specification camera support. Furthermore, IP (internet protocol) and video networks are now coming on-line which connect with CCTV and even biometric monitoring systems to central data banks as they log and record data. Unsurprisingly, many of these developments mean that high specification storage media are required. In simple terms, even the emergence of colour CCTV camera technologies is pushing up the demand for data storage.

So when your hard disk-based security system runs out of space where do you go? Many of today's manufacturers have their own proprietary data storage expansion options, but these are usually expensive and offer minimal flexibility for further modular expansion.

This is where third party external storage can really make a difference. Not just in terms of cost per gigabyte, but also in terms of flexibility and interoperability. You can attach removable hard drives to a security system and realise immediate benefits in terms of not only the capacity of information that can be stored – but also the robustness of the data environment you will create and the serviceability factor for the units themselves.

Inside the hard disk unit itself, spindle speeds of up to 15,000 revolutions per minute are not uncommon.

New layers of strength
Bringing high quality hard drive 'enclosure' technology to bear in a CCTV or other security environment could be the first step to achieving real data integrity for your security system. The hard drives you employ to record data will now be interchangeable – so servicing becomes easier and when a drive goes down it can be replaced by a non technical watchman or other operative.

Most crucially of all, a high quality enclosure brings robustness. They bring new layers of strength and security to the extra protection that a disk is then given due to their design and build. Quality drive bays are constructed with a rugged steel chassis and so protect the drive from knocks, shocks and other external physical damage.

Build quality here has another important factor on disk usage in a security environment. If drive enclosures need to be removed for legal examination they need to be able to withstand repeated removal and insertion. Lower quality enclosures are commonly built with low-grade contacts and connections that will, with repeated use, break or become unstable.

This is a real world problem. If your digital security system captures video and stores it on hard drive, you may well need to copy a section to disk to allow examination by a legal body or the police. If you need a section of video larger than seven to eight hundred megabytes you will not be able to fit a copy onto DVD or CD-ROM, so where do you go? You need to be able to remove the entire drive – and you need to be able to do it safely in the knowledge that the data will not corrupt in transport.

Removable hard disks
Taking the diverse nature of the security industry into consideration, the applications for more and more sites to deploy removable hard disks is immense. Operations with a number of remote sites such as underground stations or hospital sites can safely record security data – and easily transfer it or upgrade on-board software, by simply removing the disk.

With new European Norms (EN) and British Standards (BS) governing the build requirements for modern security systems, it's worth knowing why disks corrupt in the first place. With this knowledge on board, it is perhaps easier to make system design considerations that accommodate for maximum continuity of operation. Similarly, disaster recovery planning becomes far more straightforward.

Inside the hard disk unit itself, spindle speeds of up to 15,000 revolutions per minute are not uncommon. These high-performance disk drives can have a substantial impact on the amount of heat generated by the storage enclosure. In mission-critical security environments, if this heat is not dissipated effectively, the resulting data errors or premature device failure can be devastating.

A properly designed steel storage enclosure will provide ideal thermal properties for quick heat dissipation and ample space for effective cooling mechanisms to allow continuous heat dissipation. Lower cost, mass-produced 'fans' are no longer adequate; draft induced, turbine blowers are a better choice to ensure that hard drives experience continuous and adequate cooling.

Operations with a number of remote sites such as underground stations or hospitals can safely record security data and easily transfer it or upgrade on-board software by simply removing the disk.

Equally critical to the integrity of the storage environment is the system's power supply and the management circuitry supporting it. Disk drives must receive continuous, smooth and sufficient power to operate properly. However, the amount of power required by a drive at any one time varies depending on the function it is performing. A well-designed power system not only provides a high enough wattage, but it also assures that appro-priate levels of power are applied to the devices at all times, without causing any electrical shock, a key contributor to premature drive failure.

Speedy transfer of data
Data integrity of the storage system relies on the continuous quality of the signals transferred between the disk drives and the other system components. With the increased data transfer speeds experienced by today's storage systems, it is particularly critical that storage enclosures employ appropriate system 'corrective' measures, such as signal repeaters and re-timers capable of restoring skewed or weak signals prior to passing them along.

Intelligent PCB (printed circuit board) design is also a necessary consideration to avoid signal 'cross-talk' as transfer speeds increase. Signal degradation or interference can lead to reduced performance and data errors.

With today's hard drives operating at up to 15,000 rpm, this can have a serious impact on the disk's ability to maintain consistent operation. Protecting the drive from rotational vibration (RV) is a key factor in preventing drive damage and failures.

Housing hard drives in a rugged enclosure with excellent structural rigidity and drive fit is critical to maintaining the delicate environmental balance necessary to maximise mean time before failure (MTBF). By incorporating preventative RV testing into an enclosure's mechanical design process, it can be assured that the RV guidelines specifically put forth by major device manufactures have been met.

Installer access to drives
Finally, security installers concerned with system data integrity should incorporate plans for achieving complete access to the ongoing status of the system's disk drives, the drives' environmental conditions and the status of key enclosure components (such as the power supplies, blowers or RAID controllers).

With options such as on-board and remote monitoring available to measure and provide enclosure status, as well as the status of the entire disk array, there is no logical reason to not be in control of the disk environment at all times.

Despite being a highly reliable means of data storage, hard disk drives are still mechanical devices with an inherent failure factor that must be anticipated.

Unless disk drives are housed within a well-designed environment that is intended to accommodate the stringent demands of the latest drive technologies and applications, the risk of data loss will continue to be significant.