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101 votes
Accepted

Smell of rotten eggs in the server room

To answer the question: This is almost always a lead-acid battery failure causing the battery to vent hydrogen sulfide (H2S). The battery needs to be replaced as soon as possible. As an additional ...
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81 votes
Accepted

What are the pros and cons of having your own UPS attached to your own server hosted in a data center?

Pros: None Cons: It interrupts the flow of the Emergency Power Off (EPO) in the datacenter. If there is a life or death emergency in a datacenter, that EPO might be triggered to save someone's life....
56 votes

Smell of rotten eggs in the server room

It sounds like one of your lead-acid batteries has gone bad and is now leaking hydrogen sulfide (H2S) into the air. You will obviously want to replace the battery, but I would think some cleaning may ...
39 votes

What are the pros and cons of having your own UPS attached to your own server hosted in a data center?

Apart from low-probability scenarios, the single most important reason an unnecessary UPS really cheeses people off is that a year or two from now, it will start beeping. An UPS needs regular battery ...
  • 601
33 votes
Accepted

Can Running a Server's Redundant PSU on Different Circuits Damage It?

With multi-phase AC systems (motors, etc.), you're right, bad things can and will happen if one of the phases drops out. However, with computer PSUs, each of them operates completely separately, ...
  • 109k
33 votes
Accepted

Is it safe to use a UPS designed for desktop PCs to power a server?

I would not plug a server with a power supply capable of drawing 750 watts into a UPS which is only rated at 240. The issue isn't really that it's a "server" or "desktop" UPS. You're likely to ...
  • 5,351
26 votes

Plugging in a server rack with UPSes into a room that has its own UPS backup issues

Your typical UPS (i.e., excluding a double-conversion UPS), including all APC SmartUPS that I've worked with in the past, does nothing to the power except when running on batteries. It will draw a ...
25 votes
Accepted

How to configure UPS to restart servers in the right sequence?

The standard answer for this is "not at all". Fix the software to handle restarts in random order. If you really need SOME servers to start first (example: Active Directory) put them on USV's that are ...
  • 51.1k
23 votes

Plugging in a server rack with UPSes into a room that has its own UPS backup issues

Every data center/server room I've ever been in and worked in, that had its own UPS system, has prohibited customers, clients, etc. from using their own UPS systems. I can't speak to power harmonics, ...
  • 109k
17 votes

Is it safe to use a UPS designed for desktop PCs to power a server?

Your UPS provides power when the utility mains drops, and protects from transient under and over voltage/current conditions. Given you can plug a desktop or a server or a UPS into the same supply ...
  • 2,299
17 votes

What are the pros and cons of having your own UPS attached to your own server hosted in a data center?

You may need to run your own UPS when your datacenter doesn't quite deserve the name and it does not provide centralised UPS for you and other customers. On the other hand, if that is the case there ...
  • 73.4k
14 votes

How to configure UPS to restart servers in the right sequence?

Managed Power Distributions Units (rather than the UPS) often do support customised delays in enabling individual outlets after power is resumed. Typically that is to prevent circuit breakers from ...
  • 73.4k
10 votes
Accepted

New UPS Batteries Dying in Months

That is not well known feature of the APC Smart UPSes. Each time your UPS goes back on the wall and the batteries are recharged, controller counts the energy stored in them. Acid accumulators have ...
  • 6,894
10 votes

What are the pros and cons of having your own UPS attached to your own server hosted in a data center?

Don't forget the Electrical Code. Most have something like NEC 110.3b, "equipment must be used according to its labeling and instructions".* That gives the instructions the same force of law as the ...
8 votes

Plugging in a server rack with UPSes into a room that has its own UPS backup issues

Fire safety. The datacenter operators should be able to kill the power to the room, should an emergency happen. Your UPS units are outside of their control. Batteries themselves are dangerous. A ...
  • 614
7 votes
Accepted

Can you exceed power rating on a UPS with additional battery packs

The Wattage and VA rating of the UPS represents the load that the UPS can protect. The battery and expansion packs only exist to increase the runtime of the UPS. I would suggest multiple 2200VA UPS ...
  • 196k
7 votes

How do I pick a UPS for a graphics rendering machine?

You pick a UPS the same way you always pick a UPS: You measure the power consumption of the server under typical load (for you that will be when actually rendering) You figure out the runtime you ...
7 votes
Accepted

ZFS - enable or disable disk cache?

You should definitely enable the disk cache. The rationale is that ZFS assumes enabled disk cache and so flushes any critical writes (ie: sync write and uberblock rewrite) via appropriate and ...
  • 45.1k
6 votes

Should each 48U have their own UPS?

Stuff fails. It's part of sysadmin life. Any business plan you have that relies on a service offering 100% uptime is a bad one. Before I say anything else, let me note that I know none of the ...
  • 79k
6 votes

Cancel / block a task triggered with delay by windows "task scheduler"

This is a neat idea. I would write this for you in Powershell or C#, in a few hours, for a very modest fee. ;) Just kidding. How about this... Use Task Scheduler to create two tasks. Each task ...
  • 55.2k
6 votes

New UPS Batteries Dying in Months

My thought is that you should have an electrician check the quality of the power. I have this same issue in a number of the plants I support. Our issue is that the plants have dirty and uneven/low ...
  • 61
6 votes

Can Running a Server's Redundant PSU on Different Circuits Damage It?

The job of the power supply is to take power that is not 100% clean and make is stable. People working in data centers have been fired for not having the power supplies run on different circuits. If ...
  • 474
6 votes

How to configure UPS to restart servers in the right sequence?

I had this exact issue. The only difference being we invested in sturdy rack mounted APC power units (for example APC SmartUPS 3000 ). With the APC PowerChute network shutdown software (PowerChute ...
6 votes

Is it safe to use a UPS designed for desktop PCs to power a server?

Back-UPS is not suitable for server protection. More or less suitable is the smart-UPS that has a way more sophisticated controller inside. The typical operation cycle for a power supply when the wall ...
  • 6,894
6 votes

Plugging in a server rack with UPSes into a room that has its own UPS backup issues

Aside from the practical problems, most UPS manufacturers, including APC advise you not to do it and it will void your warranty. Additionally, using equipment not as designed may violate local ...
  • 1,206
5 votes
Accepted

Shut down Windows Server on power failure without vendor-specific third-party software

This is actually really easy most UPS's support USB and the Battery appears as a standard HID Compliant battery so say Windows sees it (and I assume Linux) as big laptop battery in effect and the ...
5 votes

UPS Requirements - Max load or actual load?

Measure the real utilization of your systems infrastructure at present and build in room for expansion, spikes in utilization and normal growth. There's nothing more than that. As for UPS design, it ...
  • 196k
5 votes
Accepted

Can I power 2x6 socket surge protected PDUs from a surge protected UPS?

No, you shouldn't use surge protected PDUs. Instead, use a plain, quality PDU without surge protection. This is recommended by APC. Also, read this for some nice background explanation.
  • 97.9k
5 votes

APC UPS replace battery illuminates

A battery can hold between 1 and 10 years. This depends on many factors like: battery lot, storage conditions, usage conditions. If the capacity suddenly dropped to a very low value, it means the ...
  • 3,020
4 votes

How to wake a server after UPS Shuts it down when Mains power is restored?

After reading many suggestions, I think that a good solution is to use any old computer (if you don't care about power consumption), or some kind of raspberry pi, connected direct to energy. So, ...

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