Tech Explained

This Month’s Case Power Consolidation

PCQ Bureau

02 Jun 2003 06:37 IST

New Update

Shilpi Kulkarni was feeling very harried. As the IT Manager of Naveen Trademart, life was never easy. The company had eight offices around the city and it was up to her small team of four people to ensure that everything was up and running all the time. So, when the Chairman announced plans to consolidate all the offices into one building outside the city, she was one of the few to welcome it wholeheartedly. At least, her team would not go crazy traveling from office to office. But now she was beginning to question her own early enthusiasm.

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Though still a good six months away, the logistics of the move were beginning to wear her down. Forget the physical movement, working out the issues of migrating two hundred-plus users, their data and applications from twelve independent servers spread across to the city to the new office was taxing by itself. Added to that was the issue of power management. Faced with frequent interruptions in power, all offices had UPSs. These systems had been bought over the years and were scattered across the various offices. Shilpi had in front of her an inventory of equipment in the various offices.

Head office. PCs: 56; Servers: 4; 10 KVA UPS with external batteries: 1, 2 KVA UPSs: 3; 1 KVA UPS 5; 500 VA

UPS: 3

Marketing office. PCs: 20; Servers: 2; 5 KVA UPS with external batteries: 1; 1 KVA UPS: 2; 500 VA UPS: 2

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Other offices. PCs: 10 approx; Servers: 1; Assorted UPSs of maximum capacity 2 KVA. Some of these UPSs were more than six to seven years old and only constant maintenance kept them going.

Expert Comment

Power Consolidation

Balu Pandian

Marketing Communication Director,

APAC, American Power Conversion

Assumptions:
l	PC load is 200 VA each	l	Redundancy is required on the critical load only
l	Server load is 700 VA each	l	UPSs older than four years need to be scrapped. Hence, all UPSs currently located in the other offices will be disposed off
l	Networking load (router/switches/hubs/modem) of 500 VA	l	All servers have single corded power supply
l	2 KVA UPSs in other offices	l	All UPSs are 1:1, that is,single phase in and single phase out
l	Server load plus networking load is critical	l	Users are located in separate areas or separate floors that can be powered by separate UPSs, that is, the load can be distributed
l	PC load is non-critical	l	Since there are only four people, some level of manageability and pre-failure diagnostics on the UPS are required
l	Minimum backup time needed on critical load is 1 hr on the UPS	l	Maximum possible utilization of existing UPS should be implemented to avoid wastage
l	Minimum backup time needed on non-critical load is 30 mins	l	Backup time of 2-4 hrs is a must as there are frequent interruptions in power
l	Generator backup is of 4 hrs	l	Assume expansion in the next one year. Hence, excess capacity of 20% should be provided for

Solution:
a) Critical load
Critical load comes to 10300 VA. This can be calculated by multiplying the number of servers by load of each server plus load of networking equipment
14 x 700 + 500 = 10300 VA or 10.3 KVA
Plan for 15—20% excess capacity for future expansion in the next one year. In case, further expansion is required, it should be possible to increase the UPS capacity, without having to buy an additional UPS.
Hence, the recommended solution for protecting the critical load should be a 12 KVA UPS.
Additionally, external batteries of the 10 and 5 KVA UPSs need to be attached with this UPS in order to provide a total of one hour of backup time for the critical load.
l	It needs to have redundancy, hence capability for additional redundant power modules
l	It needs to be scalable, hence capability to add additional power modules
l	It is protecting a critical load, hence, in case of problems, should be easily serviceable. Preferably the design should be modular, so that faulty components can be easily swapped out. At the same time, it should be hot-swappable so that the UPS need not be shut down while servicing/swapping components
b) Non-critical load
The non-critical load is 31200 VA. This is calculated by multiplying the number of PCs to the load of each PC as follows:
156 x 200 = 31200 VA or 31.2 KVA
Plan for 15-20% excess capacity for future expansion in the next one year. As and when the requirement increases beyond this capacity, additional UPSs will be need to be purchased and the oldest existing UPSs phased out.
31.2 x 1.2 = 37.44 KVA is the requirement.
It is recommend that the assorted UPSs in the other offices be scrapped as these are older than six years and have outlived their design life. Also recommend is the scrapping of the 500 VA UPSs.
The higher KVA UPSs viz,1 KVA/2 KVA/5 KVA/10 KVA can be retained because of the relatively better reliability and thereby higher design life of higher KVA UPSs.
Hence available capacity with existing UPSs = 1x10 + 1x5 + 3x2 +7x1= 28 KVA.
Purchasing an additional 10 KVA UPS with 20 mins backup time is recommended.
Implementation of these UPSs for the non-critical load:
l		The external batteries on the 10 KVA and 5 KVA UPSs need to be detached and connected with the 12 KVA UPS powering the critical load.
l		All the UPSs powering the non-critical load, that is, the 1x10 KVA existing UPS, the 1x10 KVA new UPS, the 1x5 KVA existing UPS, the 3x2 KVA existing UPS and the 7x1 KVA existing UPS will now have the minimum batteries, that is, for approximately 15-20 mins.
l		These UPSs need to be distributed across the new building in order to support the 156 PCs.
l		They will be backed up by the diesel generator (having a capacity of 4 hrs backup for the entire building load, that is, including AC, lights and IT load) in case power failure lasts longer than 15 mins. Preferably, this genset should come equipped with an AMF panel in order to allow for automatic deployment of the genset shortly after the power failure occurs.
Conclusion
Total new purchase is 12 kVA UPS with 30 minutes backup time and 10kVA UPS with 15 minutes back up time.
Redeployed UPSs are 1 KVA (7 nos), 2 KVA (3 nos), 5 KVA (1 no), and 10 KVA (1 no).

Next

Month’s Case

Other

OS Support

Navneet was faced with a rather unique problem, one he had never faced before and was not sure of how to handle. If it were a technology problem, he would not have had to spend so much time thinking about it. He would have put one of his very able juniors on the job and would have been quite sure that the job would have been taken care of. If push came to a shove, he would have himself sat down to the task. But, like we said, this was not a straightforward technology issue.

Sanjay Kumar had just joined the organization in a fairly senior sales position, from an MNC abroad. Sanjay was eligible for a notebook and Navneet had gone up to ask him about his preferences. In the few days he had been here, Sanjay had created a reputation of being a man on top of his job, but an easy person to work with. Frankly, Navneet had not expected too much in the way of inputs or demands, and, so, was fairly taken aback when Sanjay asked for an Apple PowerBook straight away. His reasoning was very simple. During his many years abroad, he had used a PowerBook extensively, and was not familiar with anything else. His opinion was that he would rather have a notebook that he was comfortable with, and spend his time ensuring that targets are met, than spend the same time learning how to operate a

new notebook.

Sanjay even found a local Mac dealer who gave a fairly impressive demo. During the demo, Navneet happened to mention that he was looking at adding more storage to his network, and the dealer came back a few days later with a demo for Apple Xserve and RAID storage, connecting them to his network.

Pricing issues apart (Navneet was confident that he could drive a mean deal), he was not sure that he wanted to take on the burden of supporting another OS and architecture. His 400-client/10-server network was based on the Intel architecture and ran Windows and Linux. The Mac was a totally unfamiliar animal to his team. There was also the issue of applications. He had site licenses to most of the regularly used applications (Office Suite, ERP, etc) in the organization. However, he wasn’t sure if Mac software would be easily available or if licenses could be treated as part of the site licenses. Also, a couple of applications were homegrown and there would be issues of porting them or their clients for one man’s use.On the other hand, Sanjay was a very compelling person, and Navneet wasn’t sure if his arguments about not wanting to support a new architecture would be accepted by Sanjay.

Shilpi was fairly sure that she would have to dump a good number, if not all, of the existing UPSs when they moved to the new office. But what should be the exact specs, configuration and topology of the new setup? How much of backup should she provide for? There was going to be a generator in the building. How much redundancy should she provide for, if any? How should she plan for future growth in power needs? Should she buy that capacity today, or should she buy a system that could add capacity as you go along. In fact, were there any with that facility? Also, was it simply a case of just buying any UPS, or was there anything else she could do to optimize power consumption at Naveen Trademart?

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