Power is required for all our servers, desktops, and other electronic devices to operate.

learn more… | top users | synonyms

181
votes
14answers
6k views

What is this very short power cable called?

I have a couple of networking components in my rack that take giant AC adapters ("power bricks") that don't fit neatly into my rackmount PDU. I have one "thingy" that is shown below, and I need to ...
49
votes
14answers
2k views

Is UPS worthwhile for non-production equipment?

Over the years, I've had to throw away a quite a few bits of computing equipment (and the like): Several ADSL routers with odd symptoms (losing wireless connections, losing wired connections, DHCP ...
40
votes
7answers
6k views

Why do we still use power supplies on datacenter servers?

Computers mainly need three voltages to work : +12V, +5V and +3,3V, all of them are DC. Why can't we just have a few (for redundancy) big power supply providing these three voltages to the entire ...
29
votes
9answers
15k views

Does CPU power management affect server performance?

I was doing some simple hand benchmarking on our (live) database server during non-peak hours, and I noticed that queries returned somewhat erratic benchmark results. I had enabled the "Balanced" ...
28
votes
9answers
13k views

UPS and power strip interactions?

Sometimes I hear that you shouldn't plug (UPS brand X / any UPS) into (power strip brand X / any power strip) because of some interaction leading to poorly conditioned power, reduced battery life, ...
28
votes
5answers
1k views

How to build and run a machine room?

The last guy quit (I think a lot of adventures begin this way?) and I've been given the job to build a new machine room. I am coordinating with 2 engineers, campus ITS, campus Facilities Management, ...
23
votes
6answers
5k views

Best practices for power cabling racks in DC

With network cables it is easy. I use velcro-ties, coloured cables, 0U vertical cable organizers from APC on side of the rack -- easy and neat. However with power cables it was always giving me ...
18
votes
7answers
2k views

Using Y power cables in a datacenter

I've always assumed that using Y cables from the PDU to redundant PSUs in the same server was totally acceptable practice, however I was recently speaking to someone that said that their colo wouldn't ...
17
votes
7answers
657 views

Power loss at company

Property management at my organization has informed me that our building will be losing power for 4 hours tomorrow. I need to be prepared for this event (we're a small organization, i'm young, ...
12
votes
4answers
615 views

Hooking up many different external HDs simultaneously

I need a large amount of external storage for an upcoming project. I'm planning on purchasing 10 2TB external drives. I need them all hooked up to a single machine at the same time. What issues ...
12
votes
4answers
620 views

What *exactly* gets screwed when I kill -9 or pull the power?

Set-Up I've been a programmer for quite some time now but I'm still a bit fuzzy on deep, internal stuff. Now. I am well aware that it's not a good idea to either: kill -9 a process (bad) ...
11
votes
13answers
22k views

What is the lifespan of an typical UPS battery?

When using a uninterruptible power supply how long does it preserve the original capacity? Say I buy a UPS that holds the necessary load for 10 minutes - I don't want it to unexpectedly come into ...
11
votes
5answers
1k views

Why is it important to ensure equipment is well-grounded?

I am installing a new ethernet switch, and the instructions say to connect the ground screw to the rack or some other kind of electrical ground. What are the risks of not ensuring that equipment is ...
11
votes
2answers
897 views

Using 48v for servers

I'm currently in the middle of a process to specify and design a new server environment for graphics and video rendering. We know we want to use blades, and we're pretty sure of our vendor decisions. ...
10
votes
4answers
775 views

Proper Sizing for PDU's/Power in Rack

I've struggled with sizing my power sources and associated PDU's in my server racks. Somehow I feel like I'm way oversizing things based on nameplate requirements on power supplies. My simplistic ...
10
votes
3answers
383 views

Should pcs be unplugged before restoring power

We have an upcoming scheduled power outage for maintenance. UPS protects our servers. But it has been suggested that all PCs should be unplugged to prevent damage from power surges when power is ...
10
votes
1answer
345 views

Daisy Chaining UPS Power Cable

I have a rackmount UPS. The UPS has a 6ft long 12AWG thick power cable that powers it from one of the server room's 20A wall plugs. The current orientation of the cabinets is not ideal. All but this ...
9
votes
6answers
2k views

Laptop waking from sleep

I have a laptop which has "recently" turned into the proverbial baby, and refuses to sleep through the night, or for that matter, through some days. I'm a little lost when it comes to trying to debug ...
9
votes
4answers
286 views

Maxing out both PDUs in a rack with redundant power

If I have a rack full of servers using redundant power supplies, and I'm keeping the amps at 80% (16A of 20A), isn't this still asking for trouble in the event of a power loss on one of the circuits? ...
9
votes
2answers
2k views

How can I calculate if a UPS is sufficient for my requirements?

I am not that of an electricity knowledgable person, so I'll try to put as much info as possible. I have a Rack Mount UPS of 1800 Watts Model: PRP 3050 RM (in total I have 2 of these - talking about ...
9
votes
1answer
282 views

Sysadmin in the Developing World: What are the differences between various kinds of power protection?

Hello I'm an ICT (InfoComTech) US Peace Corps volunteer deep in Tanzania who has the task of managing and advising concerning our college's two SunFire Sun Ray Servers and Dell Proxy server (on 2 ...
9
votes
2answers
1k views

How to check CentOS 6 Server VM Host after a power falure?

This afternoon, someone at our office decided to pull the plug out of our server because it was storming outside. They didn't shut it down, they just pulled the plug out while it was running. The ...
8
votes
3answers
2k views

Choosing the right AWG for Server Power Cables?

When getting power cables for servers, there are are various AWG (American Wire Gauge) choices to make. The ones I have noticed are 18 and 14. 14 is thicker so will be a little more stiff. But I am ...
8
votes
2answers
248 views

“Zinc Whisker” issues?

Good morning; We've been having intermittent power supplies failures in our data center that have been preliminarily attributed to "zinc whiskers". I'm just starting to read about them (I just ...
7
votes
8answers
823 views

Datacenter Power Consumption Table

Does anyone know of a good centralized resource that contains a consolidated list of server specifications relevant to the data center? Looking for Rack U sizing, power consumption, etc. for ...
7
votes
3answers
491 views

Source of PDU De-Rating?

In researching PDU's I have noticed most cite a derated current at the 80% level. For example, 30A is derated to 24A: Tripp Lite: Raritan: Does anyone have anything that shows what agency this ...
7
votes
7answers
396 views

What less obvious ways are there to misuse and damage a UPS?

I've never had an uninterruptible power supply and think of buying one. What not-so-obvious things should I not do to the UPS so that it lives longer? I don't mean some obvious abuse like ...
7
votes
6answers
5k views

Which is better - 30 AMP 220V circuit or 60 AMP 120V circuit

I'm looking for advice on which electrical service I should have run to a rack that I have in a data center. The price is the same for either a 30 AMP 220V circuit or a 60 AMP 120V curcuit. I ...
7
votes
2answers
376 views

Green-IT: How do you deal with poweroff systems in your system monitoring?

Many of you probably have completed or are contemplating Green-IT projects with the goal to power off idle or unneeded systems when demand for computer resources is low: How you did handle this ...
6
votes
6answers
290 views

Things to consider when buying PDUs

I am thinking about getting new PDUs for my racks. I would like ones that are: Metered (Maybe remote monitored) Vertical Meet my power requirements (Voltage and amperage) Right number of outlets ...
6
votes
6answers
608 views

Data Center Design and Preferences

When either selecting a data center as a co-location facility or designing a new one from scratch, what would your ideal specification be? Fundamentally, diversified power sources, multiple ISPs, ...
6
votes
6answers
503 views

Securing power cables

It's always annoyed me that while the sockets for network, serial, parallel and display cables all have securing mechanisms (ie a screw-in bolt, or a clasp) to stop them from being pulled out by ...
6
votes
6answers
479 views

Will wear induced by turning computers off in the evening be offset by energy savings?

I'm asking this here because this is primarily a huge office scenario and administrators will more likely have the answer I'm looking for. Employees' desktop computers can be either left turned on ...
6
votes
7answers
9k views

How can I calculate a server's amperage?

When ordering co-location services, a certain amount of power is included, for example 0.25 amps, 0.5 amps, 1 amps, 2 amps, etc. How do I calculate how much a server is going to require?
6
votes
4answers
4k views

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

I have several Linux servers connected to APC UPSs. They are connected to the UPS via USB and configured to shutdown if the UPS sends a signal that mains power has been lost and has not returned after ...
6
votes
2answers
7k views

ipmitool - can't find /dev/ipmi0 or /dev/ipmidev/0

Based on a previous question, I installed ipmitool (yum install ipmitool). Even after a reboot, though, i get the following error when trying to run ipmitool power status: Could not open device at ...
6
votes
5answers
3k views

Cheapest way to remotely control 120v outlet via ethernet?

What is the cheapest solution to be able to remotely power cycle a regular 120V outlet via ethernet? I've seen solutions like iBoot, but they're really expensive. Is there a cheap way to remotely ...
6
votes
2answers
4k views

How to step down voltage from 208V to 110V

I have some racks that will be fed by 208V/20A circuits. These circuits will be conditioned and battery-backed by the facility in which these racks will live. 99% of the devices in the rack will be ...
6
votes
6answers
2k views

Where to locate power outlets on server rack?

I'm building a new server room, and have to decide where I'll be locating the power outlets (120V 30AMP locking connectors) that my UPSs will be powered from. In the past I've put the outlets on the ...
5
votes
4answers
2k views

When do I need to consider 3 phase power? [closed]

Ok, I'm trying my best not to make this too subjective and provide all the information I can and if you can help make this a better question then please suggest. My friend an I have a small software ...
5
votes
7answers
1k views

Is there a solution against short power outages except UPS?

I encounter very short power outages quite often. Typically they last for just couple of seconds - perhaps the power grid maintenance staff just flips the switch to "Off" and then immediately to "On". ...
5
votes
7answers
13k views

VMware ESXi shutdown triggered by APC UPS connected via USB

I am shipping a bunch of ESXi 5.1 servers to remote offices where they will be powered via APC UPS. I would like to have the UPS trigger a shutdown of the connected server - I would then rely on the ...
5
votes
2answers
167 views

Power on machine when there is power?

Is there a solution for powering a machine back on after power loss once the power is back on? I could use wake-on-lan, but if there is a solution (software or hardware) to automatically power-up once ...
5
votes
7answers
832 views

Rackmount Power: NEMA 5 or IEC C14?

Here in the USA, most consumer power strips seem to make use of NEMA 5-20R connectors - they look something like this. However, in the rackmount/datacenter world, I see a lot of power distribution ...
5
votes
2answers
858 views

What's the maximum number of computers I can safely power on a 13-amp supply?

Due to a lack of power in a new office building, I am having to daisy chain strip plugs off a single socket. Roughly speaking, how many amps does a desktop computer with screen consume? How many ...
5
votes
2answers
326 views

Will a 300W psu drain more power than a 100W if the system only uses ~80W?

I have a NFS server that is a old mini-itx motherboard with two 2.5" drives and a no optical drive. Atm. this is powered by a external 100W psu, but I estimate it only need/uses between 60-80W. This ...
5
votes
1answer
71 views

Power Control Compartment?

I recently purchased an IBM enclosed, rolling rack that had a 6 drive server, huge battery backup, and this strange item called a "Power Control Compartment" I cannot find any good documentation ...
5
votes
2answers
104 views

UPS for 30A service to server racks

Our server rack has two 208V 30A dedicated circuits running to it, each to a PDU mounted in the rack. Most of the equipment has redundant power supplies so one goes to each PDU. I'm not sure who had ...
5
votes
1answer
202 views

Using Y split cables to connect two servers to a single PDU receptacle

We have bought a few 30amp 208v PDUs that only have 9 receptacles. The servers we are connecting to those PDUs will not use the full 30amps (at 80%, or actually 40% since we use redundant power) so we ...
5
votes
3answers
683 views

Calculating how Much Power is needed For Servers

How do I calculate how much power I need for my servers / switches / routers? This is needed when moving into a datacenter. I figure I should just add up the wattage on all the power supplies even ...