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111

I would just call it a "very short extension cord", and in fact a Google search for "short extension cord" turns up lots of results of exactly what you're looking for. E.g., these, which have a pass-through plug.


52

What'cha talking 'bout Willis? You can get 48V PSUs for most servers today. Running 12V DC over medium/long distance suffers from Voltage Drop, whereas 120V AC doesn't have this problem┬╣. Big losses there. Run high voltage AC to the rack, convert it there. The problem with 12V over long distance is you need higher amperage to transmit the same amount of ...


43

"pigtail" is a common term for these (actually any 6" to 1' power cord) in the datacenter environments I've worked in.


42

Short answer, yes. Long answer, read this: http://www.codinghorror.com/blog/archives/000632.html


33

You can also get short Y power cords. These cables (including the single variety) are sometimes called "outlet savers". I also love the 90┬░ rotating plug variety for some applications. The cord goes flat against a wall.


32

Before the outage: Power everything off - workstations, servers, printers, switches, the works. Turn off your UPS' so they don't panic when power is lost. After outage in this order: Turn on UPS Turn on networking (router, switches etc) Turn on servers Turn on workstations Turn on everything else Have a test plan ready so you can test important ...


29

Having had some 'discussions' with the inspector that comes around our offices once a year to make sure we're not being bad, I have a better idea as to what code says about this. Paraphrased from said inspector: Thou shalt not plug a power-strip into another power-strip Nor any multi-outlet device into another multi-outlet device, for it is a fire-hazard, ...


21

You can plug in that many drives via USB . . . but I wouldn't recommend it. The single biggest issue you're going to run into is the use of USB 2.0 (480Mb/sec shared across all devices on the controller). Unless you're using USB 3.0, you are going to seriously limit your disk throughput. USB was intended for temporary (hot plug) or situations where very ...


19

I think the official name is "Power Strip Liberator". Google image check: http://www.google.com/images?q=power+strip+liberator UPDATE: Sorry, I think that's a product's name (trademark), not the common name for the "thingy." But I looks like that the product is the "Coke" amongst power extension cords. :)


18

I am no electrician either, but I think you will at least lose the possibility of keeping your server up and running when doing so. On the contrary if you connect each PSU to a different power source, your server will still have an availble power source (hopefully).


18

It's not necessarily more efficient as you increase the I^2R losses. Reduce the voltage and you have to increase current in proportion but the resistive loss (not to mention the voltage drop) of power cables increases in proportion to the square of the current. Thus you need massive, thick cables too, using more copper. Telcos use typically -48V so they ...


15

You might want to distinguish between filtered power and uninterrupted power. Uninterrupted power is probably a good idea for things that you want to shutdown gracefully. Depending on your needs you might only need enough time for the shutdown to finish, resulting in a much cheaper UPS. Other devices may not need UPS at all, but only filtered power. ...


15

I've never used them because they're a single point of failure, at best. Every server I deploy into a real datacenter has each PSU plugged into a different PDU in the rack, each of which are attached to a different independent UPS, on different circuits, ideally even fed from different power feeds. If the UPS, PDU or circuit your Y-cable's attached to goes ...


14

Most of the time, there is a BIOS option for what to do when getting power back. You can set it to "Always on" or "Last State" or "Never power on" (or something like that). I prefer the second one.


13

This is because that equipment was designed to be installed anywhere in the world, and not every place has 3-wire electrical. Additionally, not every 3-wire install has a well grounded ground-wire, so having the option of creating a separate ground is a very good idea for the enterprising electronics manufacturer. What is the impact of not using the ...


12

Having just done through a datacenter shutdown in the last week, this is fresh on my mind ;). Yes, shutting everything down needs to be done. Some things can tolerate having the power yanked out from underneath them, and they typically can be identified by not having a power switch on them. Depending on what the heck the facilities people are doing, you may ...


12

I'm not sure about servers, but the current thinking in embedded devices is not to bother with steps between low-power and flat-out because the extra time involved will eat your power savings, so basically they run low power until they get any real amount of cpu load at which point they flip over to fastest-possible so they can finish the job and get back ...


12

Horizontal PDUs are a mess -- In my experience there's nothing that can be done to make these neat: You can bundle your cables neatly down the side of your rack, but when you get to the PDU they fan out into a rat's nest. For vertical ("Zero-U") PDUs you can acquire custom-length power cables (they're available from various suppliers, usually in the same ...


11

It is called a pigtail extension cord. http://www.mockett.com/furniture-hardware/technology-into-furniture-integration/power-communication-systems/plastic/pt1-90.html


11

Buy an Uninterruptible Power Supply - put it between your server and the idiots around you :)


11

Telcos have used DC in their central offices nearly exclusively, historically. In what seems to be a recurring pattern in computing, I'd argue that the IT industry moving to DC and, effectively, re-inventing the "wheel" that telcos already invented years ago is just par for the course. The last few years have seen various articles talking about using DC ...


11

Interesting question... In general, I base the system performance profile on the application and intended use of the server. I typically work with: Low-latency transaction-heavy systems. Virtualization hosts (VMware). Linux-based ERP servers. The systems that require deterministic performance and low-latency are typically set to a high-performance ...


10

You can use the PowerCfg utility to find out. It's part of Vista, no need to download it. powercfg -lastwake Will tell you what woke up your laptop. To see all devices that can wake your computer, try: powercfg -devicequery wake_armed You can turn all these devices off with Device Manager, on the Power Management tab. Unselect "Allow this device to ...


10

Flywheels are used in large data centers to cover short power gaps like yours, or to allow time for a backup generator to come on line. They are (typically) only good for 45-60 seconds, and they are expensive, but they have a longer lifetime than UPS batteries, and can make sense for a very large data center. Another approach was Google's, who integrated a ...


10

I have always turned off any type of power management on servers. I am curious to what others have experienced, but I always assumed that if the server is under-clocking, there will always be some delay to 'step up' the CPU to 100%, and in a data-center setting any delay like this is unacceptable. The data you provided seems to support this assumption. So, ...


10

You might take a look if you have not come across this site yet (http://www.datacenterknowledge.com/). A ton of white papers across the topics. Some are "marketie," but still good starting points at the very least.


10

Start with the power. It will pretty easily show you how much of everything else you need. Get a number, maybe ask the electricians, of how many KW or KVA the project is. If it's less than say 12 KW, you are talking a medium size build out. Few racks, say five, a hundred or so servers. 100 * (1 amperes) * (120 volts) = 12 000 watts = 12KW Account for ...


10

In my experience yes. The main problem is that often too many devices are left turned on and create quite a peak when power is back again, with potential damaging effects for the power supplies. This is the reason why intelligent PDU for server racks often turn devices on in a staggered mode after a power loss.


10

I seriously recommend you consult an electrician, not sys admins, for this kind of information. Nevertheless, for what you are describing there is no reason to go with 3 phase.


10

My friend an I have a small software development business. From this I gather that you're not in the infrastructure business. They can consume upwards or 2KW peak power. We may host upwards of 3 or 4 of them From this I gather that your power needs are beyond a small office's normal abilities. Then there would be air conditioning and other ...



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