On April 25th, 2008 we will be performing an upgrade on portions of our UPS system. These will bring these units up to a similar spec to our new UPS.

Anytime we perform UPS maintenance we put the UPS system in bypass, meaning that we run the facility on our own generator rather than the electrical grid. Anytime there is a transfer of power from one source to another, there is a risk of interruption. The risk is very small, and we will take every measure to minimize and eliminate that risk. Briefly, here is the process:

* Manually start the generator.

* Manually transfer the electrical load from grid to generator.
(The interruption here is measured in milliseconds, unlike a power failure, which usually lasts 7-10 seconds as the generator starts.)

* Manually put the UPS system in bypass mode.
(This routes power directly from the main power panel through to the servers, removing the UPS from the flow. This is a two-step process where the bypass bus is energized before the UPS is bypassed. This means there is no interruption.)

* Perform the required maintenance.
(This will take several hours.)

* Put the UPS system back on-line.

* Manually transfer from generator to grid power.

* Shut down the generator after a cool-down period.

We perform this procedure several times a year, so this is fairly routine. We also have over a week's supply of fuel for the generator, so runtime is not an issue. We just like to keep our clients informed of happenings here at the facility. As per usual we'll document the process here on the support blog so you can see what we're up to. We'll post reminders as the maintenance day approaches.