Managers Deal With Digital Data Dilemma

Some time ago, we covered a short list of the hot buttons to look for when selecting a digital recording or transmission system (see page 26 of July 2004 issue or click here). That common sense list of features — picture quality, ease of use, reliability and support — served as a good starting point, but we left out a key consideration: The importance of the digital data to your organization, which is often left to the salesman’s discretion.

Let’s start with a basic premise that all recording media has a life expectancy. With the exception of units that record using some sort of flash memory — which can exceed the usable life of the product — most recordable media will ultimately fail. For most digital recorders, this means the hard drives.

By accepting this premise, we are better able to come up with a strategy for coping when disaster strikes. The good news is there are plenty of options available. The bad news is that many end users select an option by default.

Doing Something, or Nothing
Let’s take a look at some of the available options at preparing for the failure of recordable media:

Do nothing — This is the option selected by the vast majority of the market, and, believe it or not, is often the appropriate one.

Wait for a product to fail, then repair or replace it. Folks in this category won’t notice a problem until they need an image and find it isn’t there.

If it is acceptable to shrug your shoulders and say, “We didn’t get it,” this is the simplest and most cost-effective way to go.

Preventive maintenance — This is an option that is rarely selected, but is cost-effective and dramatically improves system reliability.

Play back a sample of recorded video on a daily basis to ensure the unit is still recording. Periodically open up the unit and vacuum out the dust. Verify that the fans are working and check to see that all of the internal connections are snug.

Test hard drives and replace them according to the manufacturer’s mean time between failure rating (MTBF). Doing this after the first year of operation and every six months after that is usually sufficient. While this option does not cost more in terms of hardware, it does require qualified service personnel, a service plan with a good integrator or a note on your calendar to remember.

Redundant Storage as a Solution
RAID storage subsystem — This system, an acronym for “redundant array of inexpensive drives,” provides for extra hard drives which allow for the failure of a single hard drive in the array without a loss of data. It adds considerable expense to the system and is not for everyone.

RAID is very common in the IT world, where every bit of data will ultimately be recalled by someone. Studies show that more than 95 percent of the images recorded in security systems are never viewed or reviewed, making this overkill for many applications. Look carefully at the consequences of lost data before selecting this option, but embrace it if it is appropriate for you.

RAID with preventive maintenance — No matter what, you need to take care of your digital recorders if you want them to take care of you.

Even though RAID drives provide for redundancy, they need to be checked periodically and they need to be cleaned. Ventilation is especially important since there are more hard drives, which generate more heat.

Failed drives need to be replaced, as most RAID systems will not survive a second drive failure. Since all the drives are typically the same age, multiple drive failures during a short period are not uncommon.

Redundant DVRs — Some applications choose to go one better than RAID, feeding their analog signal to two different DVRs. This not only covers problems related to drive failure, but also power supply and other system issues. It can be surprisingly cost – effective, as the second back-up unit can have lower resolution or frame rate if needed.

Consider DVRs if your data is important but you don’t need all of the features that come with a top-of-the-line RAID unit. If the feature set on an embedded DVR fits your needs, you can often purchase two of them for less than the price of a single high-end RAID unit.

The downside is added rack or shelf space, power draw, heat generation and a limited feature set.

Make Sure the Data Fix Fits
Remember, while standardization is nice, one size doesn’t always fit all. If your needs vary depending on the camera location, consider some mixing and matching of the choices listed above. You can often do this by selecting different models in a manufacturer’s product line.

Be sure to check for software and data compatibility, as many manufacturers have incompatible product lines.

 

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