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Is there anything I can do to prevent the server from shutting down? (bios setting etc). the server in question is an HP Proliant ML350 G6. I've got an eaton 5110 UPS and Eaton claims that we need to buy any model beginning with a 9 (and thats close to $1k), I'm not convinced. I've seen cheap low-end APC's run on extremely similar servers and handle it just fine.

So far, i'm not pleased with the Eaton (it wasn't purchased by me) i would have stuck with APC given the choice.

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"Shutting down" as "turning itself off immediately" or as "orderly OS shutdown"? – haimg Oct 3 '11 at 14:45
Turns off immedialty. Straight to a black screen. I would be fine if it were an orderly OS shutdown, because that's the ultimate goal. – TehBanz Oct 3 '11 at 15:02
up vote 14 down vote accepted

Typical PC power supply hold-up time is about 20ms, according to PC Power supply specifications and certifications web site. It means that your server should be able to survive 5ms switchover without any problems.

So. One of the following:

  1. Either your server's power supply's capacitors are near the end of their life span, so it cannot hold even for 5ms, in which case I'd say you need to replace the power supply since it's not within any reasonable spec.

  2. Or your UPS switchover time is considerably larger than 5ms, in which case you need to get another UPS since this one is faulty (not underpowered, just bad, warranty case, etc.)

  3. Your server requires more than 1500 VA your UPS can supply, in which case UPS shuts down because it's overloaded.

First, rule out #3 above. Then, the easiest way to know if it's #1 or #2 is to try a different server with that UPS, or a different UPS with your server.

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I spoke with Eaton on the phone about this, the hardware tech confirmed a 5 MS switch-over. this replaced our old UPS which worked fine and was an old Eaton. I'll request an RMA as I Believe this is faulty hardware. If the RMA doesn't work it's back to APC hopefully! Thanks for the insight. – TehBanz Oct 3 '11 at 16:30
@TehBanz - You should confirm it yourself. All the hardware tech wanted to do was upsell you on better hardware ( which you might need ) so confirm its not your hardware that is going bad before you RMA it. – Ramhound Oct 3 '11 at 17:23
@Ramhound I believe it is a hardware fault, i've another server on the exact same ups (very similar HP server just a newer model) and i pulled the power on the server and the ups kicks over in due time. – TehBanz Oct 3 '11 at 17:51

The server shuts off because it's out of power. If the Eaton UPS cannot get power to the server withint the appropriate amount of time to prevent the server running out of power, the UPS is simply not capable and you should go with your instincts and purchase a better UPS.

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You need an 'on-line' UPS. That means that the UPS is ALWAYS providing power and simultaneously keeping it's battery topped up. When incoming power fails, it just keeps right on providing power. With these guys there is NO switch-over time during which your server isn't getting power.

You should only use something with a switch over time if you can prove that your server is able to survive that time (as in, you can look at the server's specs and see that it has X milliseconds of survival, and X is greater than the 5 ms your UPS takes to switch).

I think most of APC's products fall into the 'on-line' category, but be sure to examine the specs carefully before buying.

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Online UPS is the only way to go unless it is non-critical equipment in use. The other upside of an online UPS is that it isolates the equipment from the power grid, which does wonders for surge/spike protection.

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