Changing a UPS

[Jobos]

We're got a smart UPS 1500 that has gone faulty and is feeding a Dell 2900 with redundant power supplies. I've changed the battery in this UPS before so this time I'm just going to swap the UPS for a new one.

 

Without powering down the server can I take one of the power leads from the old UPS and connect it to the new UPS then connect the other power lead?

[Michael]

You probably can but it's not something I have ever tried or would ever recommend.

[AceDaz]

In theory its possible, it also tests your backup power supply.

 

Shouldn't the second power supply (in theory) be connected to another UPS and that is perhaps connected to a different mains ring?

[Hightower]

Yes, you should be able to no problem - that's what the redundant PSU is for hehe.

 

You don't have both leads going into the same UPS though do you? Just it stops the 'redundant' part of having 2 PSU's - if the UPS fails your server fails.

 

Where as if you have one PSU to a UPS and the other PSU to a different UPS you introduce redundancy.

 

Off topic but worth mentioning

[AIT]

We're got a smart UPS 1500 that has gone faulty and is feeding a Dell 2900 with redundant power supplies. I've changed the battery in this UPS before so this time I'm just going to swap the UPS for a new one.

 

Without powering down the server can I take one of the power leads from the old UPS and connect it to the new UPS then connect the other power lead?

 

you can do it and I have done it. would only recommend doing this if you are sure that the ups's are fed from the same ring main.

[teejay]

Yes you can, normal thing to do. For extra redundancy have each socket plugged into different UPS's.

[Michael]

I understand what you guys are all saying, 2 x seperate UPS but I am pretty sure I have read somewhere APC do not recommend you unplug or plug in equipment when it's all powered up.

[Hightower]

I understand what you guys are all saying, 2 x seperate UPS but I am pretty sure I have read somewhere APC do not recommend you unplug or plug in equipment when it's all powered up.

 

Well they would say that to cover their own backs. But it is doable, and shouldn't cause any harm.

[powdarrmonkey]

You don't have both leads going into the same UPS though do you? Just it stops the 'redundant' part of having 2 PSU's - if the UPS fails your server fails.

 

Not if a PSU blows up, a la Optiplex.

[Hightower]

Not if a PSU blows up, a la Optiplex.

 

Uh huh.... but if the UPS goes pop you lose power to the server (as one UPS is feeding the server to both PSU's)

[powdarrmonkey]

Uh huh.... but if the UPS goes pop you lose power to the server (as one UPS is feeding the server to both PSU's)

 

But if you've only got one UPS anyway, that hardly matters. If you've got one UPS and redundant PSUs, I say make the most of the PSUs.

 

I suppose you could argue that with one UPS, the safest bet is to plug one PSU direct into the mains. Then if there's a power outage, you've got UPS, and if the UPS goes you've got raw mains. Bit screwed if the UPS blows and takes out your MCBs though.

[Hightower]

But if you've only got one UPS anyway, that hardly matters. If you've got one UPS and redundant PSUs, I say make the most of the PSUs.

 

I honestly don't know what we're disagreeing on here!

[sidewinder]

Ive done it plenty of times, good way to avoid downtime. Managed to rearrange leads when I bought a new UPS while only turning 2 out of 10 servers off with this method.

 

I've got 3 main UPS's, and all servers have both PSU's connected to different ones

[Jobos]

Thanks for the advice guys... it worked fine. The server stayed up and the worst I got was an event log showing one of the PSU's went down for a few seconds. All in all a good outcome