Hello,


I read about dedicated servers, and people refer to a server being 1U, or 2U or 4U. What is this? How is it used? Thanks for your help

a u AKA RU is space. A one RU server is the slim line ones like the dell 1550's etc and they go up in size.

So a U / RU is simply the size of the server

Oh, so it deals with the server itself, not space or bandwidth? Are there specific deminisions 1U 2U and 4U entail? Thanks

I stand corrected. Thanks for the update.

Alright,

So are these sizes for rack mount stations? Or, why does there need to be a size put on them? that size has to corolate with somthing. Thanks

1.75 inches

Well if you think that a company has one cabinet. The cabinet can only hold (this is an arbitary number) 40units high of space. This means the company can have 40 1U servers, so if you think that a 2U server takes up twice the space, you need to charge more as it's taking space you could use for two 1U clients.

Oh, I see. These are just size seting doubling each time, EX. 1u 1inch 2U 2inch 4U 4inch and so on. Do 4U servers generally have more processors? Memory? since they are bigger? More power supplies? Thanks

I'm not an expert on the racking hardware as such but i'd guess you're correct. A 4U server i'd (guess) would have more drives i.e RAID or something?

I know that some cases you can fit more than one physical server into it, so in a 4U case you may have 8 servers or something

I am no expect here too but the larger U would represent a bigger form factor. Bigger U doesn't always have to mean more processors but just how much of the precious rackmount space it would consume. I guess you could consider it as lettable rental space.

In a datacenter, usually you will have racks full of servers, the smaller the form factor, the more they can packed into the assigned space.

For instance, if the datacenter only has 'whitebox' tower pc as servers, those would generally be bigger and take up more space, ie larger U factor. As a datacenter, you probably would not make as much as you would, if you were to only stick to 1U servers.

Oh great, so a space thing. Is there any advantage with going with a 1U say over a 4U? cooling maybe? Thanks

A 1U would generally have a smaller form factor and thus components are more compact. While a 4U with the same system specs would have more internal space for internal air circulation.

Well, generally it is just a space thing and how much you can pack within a given space.

Of course, if you are looking at building a datacenter with a rack full of servers, you generally have one really 'hot' rack and thus air-conditioning and all the cooling facilities are extremely important in that respect to keep everything running at optimal performance with the minimum of downtime due to overheating.

That's probably why when you look at datacenter specs, there is a great emphasis on cooling systems and climate control.

Oh very nice. Does the form factor fit for rakcs as well? Say I purchase a rack, would it need to comply with the 1U-4U rack system? For ease of use that kinda thing? Thanks

You might want to contact the rackmount resellers or manufacturers in that respect. I believe it is all in the design.

Check out :

http://www.rackmount.com or
http://www.eia-rackmount-case.com/

There are more around but that should start you off.

my servers were 9 or 11 u I forgot

WOW, 9U must be pretty thick eh.

They were damn heavy

Originally posted by intigret
WOW, 9U must be pretty thick eh.

This is probably standing upright. Most towers will lay on their side and only take up 4 or 5 U depending upon the width.

A U is an industry term for Unit. A unit is 1.75" of heighth in a cabinet. Most cabinets are 19" wide but some are 23". 19" is standard.

The size doesn't mean it is better. Typically a 1U server is built with size and airflow in mind and typically will have more fans. They are also designed better for use in a cabinet as fresh air enters the server from the front and fans blow it through the machine and out the back. This keeps the airflow moving through the server the same direction and is usually quite efficient (although I have seen some VERY bad designs, most work very well).

If you purchase a case from a reputable mfg, they will typically be set up to efficiently accommodate airflow.

So, to answer your question, a U is a unit of measurement for a rack mounted server equalling 1.75" tall by 19" wide.

I tried to put two of them on a shelf on their sides, but they were still too wide to fit to my satisfaction. One of them was over the edge a bit and a little unstable, so i went with two seperate shelves

Originally posted by The Laughing Cow
I'm not an expert on the racking hardware as such but i'd guess you're correct. A 4U server i'd (guess) would have more drives i.e RAID or something?

I know that some cases you can fit more than one physical server into it, so in a 4U case you may have 8 servers or something

Well... That's like saying that if I have a bigger car, there are more people in it -- if you want to drive lots of people, you want a big car, but you don't have to drive lots of people if you have a big car. Similarly, a 4U server could have just one harddrive, although you are somewhat correct -- a lot of massive RAID servers are in 3U to 4U cases. (Heh, did you see Maxtor's new 320 GB hard drives? Some 1U cases can hold up to four hard drives... So in theory, you could cram 1,280 GB of storage into a 1U rack... *drools*)

As far as multiple servers in a single case... I'm not sure what you're referring to. There are 'blade servers' which have a number of things on the front looking somewhat like oversized PCI cards, each of which is actually a server. (These are somewhat new, and seem to be ridiculously expensive still.) However, you may also be referring to simple 'cabinet' (roughly the size of a refrigerator, though probably only about half as wide), which you put rackmount servers in. As someone else stated, they hold 40-44 (I think 42 is the average) U each.