A reliable uninterruptible power supply (UPS) is an essential element of an information technology infrastructure if organisations want to stay in business, especially now that global 24x7 e-commerce is becoming the norm. Organisations need only look at Qantas' experience at the end of July when three of its UPSs were knocked out -- stalling IT operations for a number of hours and causing flight delays -- to realise that reliable UPSs are just as vital as being Y2K compliant. Laura Wonnacott, at the test centre of Computerworld affiliate InfoWorld, and Merri Mack canvass the issues for IT managers looking for a UPS solution A common occurrence, but in this purely hypothetical case, is where additions to a computer room have taken their toll on an existing UPS.
Typically, there would be high-end servers with a lot of fault tolerance, including redundant power supplies, she said.
During electrical failures the company used to be able to deliver power for several hours, but can now sustain an uptime of less than one hour. It cannot upgrade its current UPS and is looking for a new power solution. The organisation wants comparisons of UPSs, the knowledge to size up power needs and how to find the best solution for its business.
So many people are writing about electronic commerce and networking solutions these days, and not too much is said about a basic, but very essential component in the enterprise -- power. Finding the best power solution for your business is not an easy task, and there is plenty of opportunity along the way to stumble. Planning well from the start is the best way.
First, work with more than one vendor in order to size your power needs. If all vendors provide a similar recommendation for capacity, which is expressed in kilovolt-amps (KVA), then you know you're close.
Be sure your electrician provides you with bids from more than a single vendor. If not, ask for more or seek your own. If your power requirements are hefty, then most probably your UPS solution will weigh a lot (the UPS in the InfoWorld Test Centre weighs 5443kg). You may have to work closely with your facilities management team to safely place your power equipment.
The Test Centre's infrastructure architect, Dan Seoane, recently worked with a structural engineer to find the proper location for our heavy power solution. We chose to split the load across three structural beams to provide the safest support for the heavy batteries and components. We would also hate to crush the people on the floor below us, even if they are in another department. Without a doubt, seek the advice of a structural engineer, especially if you suspect that the weight of your equipment is near, equals, or exceeds, your floor's capacity.
As you can see, it's quite a process and can involve more than your IT team.
In terms of technology, you'll also need to decide the best solution for your business.
Basically, there are three types of UPSs. The first is a standby UPS. These are offline systems that do not regulate voltage and frequency changes. Essentially, power simply passes through the equipment.
When voltage or frequency changes become severe and constitute a power problem, the standby inverter converts DC battery power to AC power in order to run your systems. This is the lowest UPS solution and provides the least protection.
The second level, a line-interactive UPS, provides better support vs a standby system. These systems are often referred to as hybrid, or ferroresonant, and combine portions of both online and offline functionality.
A line-interactive UPS adjusts the voltage before passing it to your systems, and uses its battery to regulate the fluctuations. Line-interactive UPSs provide more regulation than standby UPS, but at the cost of battery life.
The third and best UPS uses online technology. Online systems continuously use the inverter to create regulated AC power. Use of the batteries is limited compared with interactive UPS technologies.
If you require unlimited protection against power surges, high-voltage spikes, switching transients, power sags, line noise, frequency variation, brownouts, and power failures, then an online UPS is the only way to go. If you're looking to protect critical equipment along with important data, then online is still the way to go. If you're not concerned about power surges or switching transients, and your systems are less critical, then a line-interactive UPS may work. The Test Centre recently chose an online 80KVA UPS from Powerware.
In addition to addressing all of the business issues and choosing the right battery technology for your organisation, you must also be aware of the management options among the UPS alternatives. A must-have option is to allow for the gentle shutdown of your servers when battery power is running low. Many UPSs also provide Simple Network Management Protocol (SNMP), a popular communications and control management standard that is used to provide many tasks -- including managing power across the network. SNMP provides the capability to send statistics or alerts about the UPS, as well as about other devices.
Be sure to check out what kind of SNMP support is provided. High-end systems will provide loads of information to control, set alarms and traps, and monitor the status of the UPS.
There are plenty of costs associated with implementing a new power solution. Be careful not only to search out and price the best UPS for your business, but also to search out all the costs involved, including shipping and additional labour, in implementing the UPS.
Remember, a UPS is only as good as its batteries are fresh and there are ongoing costs associated with batteries. Like most devices in the enterprise, UPSs require regular maintenance and attention. Similar to our ageing bodies, batteries wear out. Unlike us, though, batteries can be replaced.
There are a few factors that directly affect battery life. A battery's capacity is based on a temperature of 25 degrees Celsius or 77 degrees Fahrenheit. Deviate from that, though, and you will affect the battery's life.
Though we have not tested this in the InfoWorld Test Centre, a rule of thumb for calculating battery life related to temperature states that for every 8.3 degrees C or 15 degrees Fahrenheit average annual temperature above 25 degrees Celsius, the life of the battery is reduced by 50 per cent.
Cycling (not bicycling) also affects battery life. During a power glitch or failure, the UPS relies on its batteries. Once power is restored, the batteries are recharged. Every discharge and recharge reduces the capacity of the battery. The length of the discharge cycle relates to the reduction in battery capacity. The longer the discharge, the higher the reduction.
Battery maintenance and service also has a direct effect on the life of the batteries. Remember, there is no such thing as a "maintenance-free" battery. Sure, there are batteries that don't require liquid fill, but you must maintain all of them.
All enterprise-size UPSs should provide tools for monitoring batteries. You should also perform voltage checks, load testing, cleaning, and retorquing of connections as part of a regular maintenance check.
If you fail to maintain your batteries, they may experience resistance at the terminals, improper loading, lower protection -- even an early death.
Several people have asked how do you know when your batteries are worn out and need to be replaced. There's no perfect answer, but you should monitor your battery capacity and understand how temperature, cycling, and maintenance affect your batteries. When the batteries can no longer sustain the loads you require, it's definitely time to replace them.
According to the IEEE, the end of useful life for a battery is when it can no longer supply 80 per cent of its rated capacity in amp hours. Once your battery dips below the 80 per cent mark, it goes downhill fast.
Finally, if you have not exceeded the capacity of your UPS, and you are looking to extend uptimes, a generator may be your best solution. It may not be an option for all buildings, but it is a must-have for heavy-duty data centres. The UPS will handle the short downtimes and the period required for the generator to kick in.
A diesel generator with an automatic switch is recommended. The switch will start the generator within seconds of loss of building power and then switch the UPS source to generator power.
Depending on the load and run times you require, be sure to have an adequate fuel tank. You'll want to make sure this tank stays full too, so be sure to get a maintenance contract on the diesel fuel; and if it's crucially important, pay a little extra for priority service.