| Have you ever been tasked to find storage for | | | | the recording equipment and the railways to store |
| servers? Well, if you have you will know how | | | | signal relays. |
| frustrating it can be, especially with all the different | | | | A rack's mounting fixtures are called mounting rails |
| terminology. | | | | and run vertically, top to bottom in the rack, each |
| When you are looking for server storage, you get a | | | | rails is 5/8" wide with a gap between them of 17.75 |
| mixture of conflicting information, the racks are called | | | | inches, giving the overall internal rack size of 19 inch. |
| 19" rack mount racks, the width and depth is in | | | | You mount the equipment to the mounting rails; |
| millimeters and the mounting post's are in U's. | | | | some racks have pre-drilled holes that are tapped to |
| A 19 inch rack is a standardized system for mounting | | | | take the bolt that is supplied with the server, other |
| various electronic equipment in a rack 19" wide, the | | | | racks have cage nuts, these are nuts that are help |
| rack takes its' name from the dimensions between | | | | captive in steel wrap that fits snugly into the square |
| the mounting rails at the front and rear of the racks. | | | | mounting holes in the rails. |
| The racks can come in different depths: 600 mm | | | | If you were to store a piece of electronic equipment |
| deep, 800 mm deep, 1,000 mm deep and different | | | | for example that is 450mm deep in a 600mm deep |
| widths: 600 mm wide and 800 mm wide. This totally | | | | rack, (this depth would be dictated by the deepest |
| depends upon what equipment is being stored in the | | | | piece of equipment to be mounted), that is heavy, |
| racks. | | | | you would mount support rails, these run from the |
| The internal storage heights are called "U's", this is a | | | | front rails to the rear rails in the rack and distribute |
| measurement that equals 44.45 mm or 1.75", for | | | | the load evenly. |
| example a rack mount server comes in 1U, 2U 4U, so | | | | Cooling is essential, if you plan on filling a rack to its |
| for example a 42U rack will theoretically | | | | capacity, there are several ways to cool a rack. |
| accommodate 10 x 4U servers. However you do | | | | Firstly, if you are storing only servers, you will require |
| have to allow for air flow, as you do not want the | | | | front to rear cooling, this is achieved in data centers |
| cabinet to over heat, so for every 4U of space used | | | | with air conditioned rooms and vented front and rear |
| a gap of 1U is left blank, this can be closed off using | | | | doors, these doors have either fine slots or holes in |
| blanking plates - this is the Industry standard. Some | | | | them for the air to be drawn into the cabinet and |
| say the letter U is used as a standard for the word | | | | cool each server. |
| Unit. The standard the racks were created by the | | | | The second option is to have air blown into the racks |
| Electronic Industries Alliance and is referred to as | | | | from the void in the floor and exhausted from the |
| EIA-310-D. | | | | room, this is more expensive. |
| When we call the servers and selves 1U, they are | | | | The final option is to have a fan unit or air |
| not exactly 1.75 inches (1U), they are 1/32 inch | | | | conditioning unit fitted into the roof recess, these |
| smaller (normally 1.719 inches instead of 1.75 inches) | | | | come in different configurations to suit the application. |
| and this is allowing a small tolerance throughout the | | | | Some companies like to bay (join together - this is |
| cabinet, so the equipment will not catch on other | | | | achieved with a baying kit and comprises of 4 long |
| equipment in the rack. | | | | bolts) 2 racks, 1 storing the active equipment |
| Where are these racks used? They are used in | | | | (servers) and 1 storing the passive equipment (hubs, |
| telecommunications applications for storing all the | | | | routers, etc) if this is the case the racks need to be |
| data networks and telephone systems, ISP's to host | | | | earth bonded, so that if there is a short circuit no |
| all the websites, the audio industry to accommodate | | | | one gets an electrical shock. |