# Rack diagram (RackDiag)

RackDiag draws a rack elevation from a list of units. Multi-unit equipment declares a span, and the empty units stay visible, which is the point.

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## What this example shows

* Rack height declared once at the top.
* Equipment placed at a unit number, with a span.
* Descriptions carrying the model.

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## A worked example

Open it, edit it, or copy the source below.

![Rack diagram (RackDiag)](https://help.gocapable.com/images/att1424097386.svg)

The source, which you can paste into a new diagram and edit:

```
rackdiag {
  24U;
  1: UPS [2U, description = "APC SMT3000"];
  3: PDU;
  4: Patch panel A [description = "1-24"];
  5: Patch panel B [description = "25-48"];
  6: Core switch [description = "48 port, 10G uplinks"];
  7: ToR switch;
  9: App server 01 [2U];
  11: App server 02 [2U];
  13: App server 03 [2U];
  16: Storage array [4U, description = "24 bay"];
  22: Console;
}
```

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## Making it your own

* Units count from the bottom, as they do in the room.
* Leave gaps out of the list; empty units are capacity, and capacity is why people look.
* Draw the rear as a second rack if cabling or power matters.

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## Related

[System context (Structurizr)One model, and views onto it.](https://help.gocapable.com/diagrams/system-context-structurizr.html)

[Class hierarchy (Nomnoml)UML with almost no ceremony.](https://help.gocapable.com/diagrams/class-hierarchy-nomnoml.html)

[More languagesBack to the rest of these examples.](https://help.gocapable.com/diagrams/more-languages.html)

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_Specialists. Borrow one when you need it._