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Nov 07 2015

Fujitsu FJBU: The Better Alternative to Classic UPS


Aside from earthquakes, fires and floods, there are only very few things IT departments dread as much as current fluctuations, power outages, and the data and revenue losses that follow. To counter these, they will typically deploy external uninterruptible power supplies (UPSs) to keep servers and storage systems running until they can be shut down in organized manner. The problem with UPSs, however, is that they're bulky, expensive and hard to manage. Fujitsu's Integrated Battery Backup Unit for PRIMERGY Servers (FJBU) is a far better alternative.

"Remember the old Queen song Keep Yourself Alive from their first album? That's basically what UPSs are good for – if we can't keep the power up for a couple of minutes, we might as well close up shop." – That's what a skilled server admin told me when I took on my first summer job at a local ASP in the late 1990s. He did sound a little over-dramatic, but the truth is that during that summer the area was plagued by voltage drops and blackouts, and so repeated outages might have caused severe financial losses had we not been prepared. Since then, a lot of water has flowed under the bridge, but the lesson still sticks with me today: if you operate a couple of servers, see to it that power supply is ensured for a few minutes so you may shut them down yourself before they crash. The problem with conducting such a graceful shutdown is that it typically requires an extra piece of hardware – and an admin on board who's capable of running the relatively intricate process within five minutes or less. Surprisingly enough, despite many improvements in data center technology the issue still persists today, and companies have to stick with the old concept because alternatives are hard to find. Or at least they were until Fujitsu's FJBU came along.

Main Challenges
So what exactly are the key challenges when working with standard UPS solutions? As outlined above, the answer is threefold:

  • Size – conventional UPSs are often large and heavy. eating up valuable rack and floor space. In fact, they may even turn into full-blown cabinets in a midsize data center or server farm. Plus, there must be extra room for external cabling.
  • Cost – while small models usually sell for three-digit amounts, more powerful solutions may easily cost a few thousand dollars or more. In addition to the hardware investment, using a classic UPS also heightens operating expenses, as it draws power and emits extra heat, thus driving up cooling costs. Needless to say, these costs increase as data centers grow.
  • Complexity – each UPS must be integrated into existing hard- and software environments, which makes the already complex shutdown process even more arduous.

A typical setup is shown in Fig. 1 below.


Fig. 1

Fig. 1: Traditional UPS Setup


What It Is and How It Works
By contrast, the Integrated Battery Backup Unit for PRIMERGY Servers (Fujitsu Backup Unit or FJBU for short) aims to simplify the entire job of providing short-term supply of emergency power. The solution takes Fujitsu's modular approach – the concept of building servers from interchangeable standard components – one step further. The FJBU has the same size as any of our modular power supplies and can thus be fitted into the same slots to replace a redundant PSU, as shown in Fig. 2. The new, simpler setup eliminates the need for extra floor space and external wiring. What's more, as an integral part of the system the FJBU draws power from the same AC source as the other components, which drastically cuts standby power consumption and heat emissions.


Fig. 2

Fig. 2: Simplified Setup with FJBU


Figures 3 to 6 shows the four basic stages of FJBU operation. In Fig. 3, the AC power is on, and the larger part of the current flows from the PSU through the power backplane to the mainboard, while a smaller amount of electricity is redirected to the FJBU for charging (cf. the red arrows). Charging consumes 25 watts over the course of five hours until the FJBU is fully loaded.


Fig. 3

Fig. 3: FJBU Operation, Step 1 – Charging


Fig. 4 shows what happens once that state is achieved: charging stops automatically, and the FJBU switches to standby mode. During standby, the unit monitors the system, watching out for AC power decreases and failures.


Fig. 4

Fig. 4: FJBU Operation, Step 2 – Standby and Monitoring


In Fig. 5, AC power is still present, but has dropped below a predefined threshold. In this case the FJBU kicks in and starts discharging immediately, giving off just enough power to fill the gap. As a result, the server draws power from both the primary AC source and the backup unit, so that all applications stay up and running. The risk of losing data is virtually omitted.


Fig. 5

Fig. 5: FJBU Operation, Step 3 – Partial Discharge to Compensate Voltage Drop


Finally, Fig. 6 shows how the FJBU immediately takes over in case of a power failure. If the AC can be restored in due time the system switches back to normal operation. Otherwise, the server will be shut down using the ServerView® management program.


Fig. 6

Fig. 6: FJBU Operation, Step 4 – Full Discharge to Compensate Power Failure


Benefits and Advantages
Space savings, cost reduction and simplification through automation of the failover/shutdown process are all valid arguments that speak for deploying FJBUs. These core benefits are underpinned by a set of less obvious, but equally important technical advantages:

  • FJBUs are powered by NiMH batteries that provide a large capacity of 23 Wh (watt-hours) and a backup duration time (total runtime in case of a power failure) of five minutes at 280 W. In addition, NiMH batteries are known for their longevity and easily last through the typical 5-year lifespan of a PRIMERGY server; whereas conventional UPS solutions with valve-regulated lead-acid batteries (VRLAs) need a replacement after approximately 2.5 years. NiMH batteries support Fujitsu's unique Cool-safe® ATD technology and are safe for office as well as data center installations because they rely on a water-soluble solvent. As a result, they may be rolled out to data centers in large capacities without declaration – for VRLAs, a declaration is mandatory.
  • Traditional UPS devices often suffer from two issues that may result in temporary malfunction and/or data loss. One is that the switching of power provisions from AC to battery may cause a short-lived disruption or blackout that lasts for a few milliseconds – enough to miss a substantial number of instruction cycles. The other affects full-time, inverter-type devices; here, the conversion efficiency ratio, i.e. the ratio between the input needed to charge the UPS and its output, may decline over time. Fujitsu's FJBU uses independent backup controls and thus avoids both problems.

Fujitsu's Integrated Battery Backup Units have been available since July, both as built-in components and PSU replacements for PRIMERGY RX1330 M1 and TX1330 M1 servers. They will also be compatible with the upcoming second generation of these servers, due out this month.

Florian Frimmel


About the Author:

Florian Frimmel

Global Product Marketing Manager, responsible for PRIMERGY tower and scale-out servers, at Fujitsu 


Comments on this article

FJBU with VMware?
November 18, 2015, 10:07 steve-os
Interesting product. Is it possible to use the FJBU with VMware virtualization? By now I use the APC-USV and route the communication through the virtualization (Com or USB) and use the PowerChute to shut down the whole server.
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