One UPS, or two?

[Anonymous user]

I am planning on upgrading equipment we have installed in a single rack. The existing rack has two power cords - one supplied a set of power cords on the left side of the rack, the other supplies power to cords on the right. 208 volts.

Right now all the equipment is supports by a Matrix 3000 UPS. most of the new equipment has multiple power supplies. I was thinking to connect one power supply to the right side of the rack, and the other two the left. What I wondered is rather than replacing the Matrix 3000 with a single, larger UPS would there be a problem of using two UPSs, one to power the RH side of the rack, and the other on the left? This would allow me to split the load between two existing 30 amp, 208 volt circuits and also avoid having to hire someone to come in and hardwire a single, larger UPS.

One large UPS seems simple enough, but two (so long as I select large enough models) does remove a single point of failure...course I don't know if APC's software could/would monitor multiple UPSs supplying a single server.

Any guidance would be welcome.

[Anonymous user]

If each UPS has a Network Management Card, you could configure the PowerChute Network Shutdown software agent on each server to monitor both UPS. In this configuration, a graceful shutdown would not start unless both UPSs reached your defined shutdown conditions.

It is absolutely essential that either UPS be able to handle the full load. Otherwise, if a UPS fails or runs out of battery power, the other would reach an overload condition when it became the sole power supply for the rack.

APC Network Management Cards:
http://www.apc.com/products/family/index.cfm?id=98

[Anonymous user · Accepted solution]

I am planning on upgrading equipment we have installed in a single rack. The existing rack has two power cords - one supplied a set of power cords on the left side of the rack, the other supplies power to cords on the right. 208 volts.

Right now all the equipment is supports by a Matrix 3000 UPS. most of the new equipment has multiple power supplies. I was thinking to connect one power supply to the right side of the rack, and the other two the left. What I wondered is rather than replacing the Matrix 3000 with a single, larger UPS would there be a problem of using two UPSs, one to power the RH side of the rack, and the other on the left? This would allow me to split the load between two existing 30 amp, 208 volt circuits and also avoid having to hire someone to come in and hardwire a single, larger UPS.

One large UPS seems simple enough, but two (so long as I select large enough models) does remove a single point of failure...course I don't know if APC's software could/would monitor multiple UPSs supplying a single server.

Any guidance would be welcome.