RackML

An open XML schema for describing datacenter racks, appliances, ports, slots, and connections with dimensional precision.

RackML (Rack Markup Language) is a human-readable, XML-based format for modeling physical datacenter infrastructure. It captures rack geometry, equipment placement, port layouts, and cable connections — all with real-world dimensional accuracy down to the millimeter.

Why RackML?

Datacenter planning today is fragmented across 2D diagrams, spreadsheets, and proprietary vendor tools that don't talk to each other. RackML provides a vendor-neutral, open standard that:

• Describes physical reality — rack post geometry, appliance dimensions, port positions on specific faces
• Models connections — network, power, and fiber cabling with cable type metadata
• Supports modular hardware — slot/component hierarchy for line cards, PSUs, and expansion modules
• Uses real units — millimeters, meters, and rack units (e.g. 1U = 44.45mm per EIA-310)
• Is plain XML — version-controllable, diffable, parseable by any language

Quickstart

A minimal valid RackML document:

<rack name="my-rack" height="42">
    <appliance name="server1" y="1u" type="server" />
</rack>

This creates a standard 42U rack with a single server at position 1U.

Element Hierarchy

rack
├── appliance
│   ├── slot
│   │   └── component
│   │       └── port
│   ├── port
│   └── annotation
├── connection
└── annotation

Dimensional Units

All size and position attributes accept values with explicit unit suffixes:

Unit	Suffix	Description	Example
Millimeters	mm	Absolute measurement	size_x="440mm"
Meters	m	Absolute measurement	D="1m"
Rack Units	u	1U = 44.45mm (EIA-310)	y="10u", size_y="2u"

Bare numbers without a suffix are interpreted as millimeters (e.g., "440" is equivalent to "440mm").

Common Attributes

Most elements inherit these attributes for identification, sizing, and positioning.

Identification & Metadata

Attribute	Type	Required	Description
id	string	No	Document-unique identifier (XML ID type)
name	string	No	Human-readable label
sku	string	No	Part number or stock-keeping unit
weight	number	No	Weight in kilograms

Size & Position

Attribute	Type	Required	Description
size_x	dimension	No	Width
size_y	dimension	No	Height
size_z	dimension	No	Depth
x	dimension	No	X position relative to parent
y	dimension	No	Y position relative to parent
z	dimension	No	Z position relative to parent

Bezel

Attribute	Type	Required	Description
Bd	dimension	No	Bezel depth
Bw	dimension	No	Bezel width

Element Reference

<rack> — Root Element

The rack enclosure. All other elements are children of <rack>.

Attribute	Type	Required	Description
version	string	No	RackML schema version (e.g., "1.0.0")
height	positiveInteger	Yes	Number of rack units (e.g., "42")
A	dimension	No	Horizontal distance between inner edges of front posts
B	dimension	No	Horizontal distance between center of mounting holes
C	dimension	No	Horizontal distance between outer edges of front posts
D	dimension	No	Rack depth
U	dimension	No	Physical size of one rack unit (default: "44.45mm")

Child elements: <appliance>, <connection>, <annotation>

<rack name="datacenter-rack-01" height="42" 
      A="450mm" B="465mm" C="483.4mm" D="1m" U="44.45mm">
    <!-- appliances, connections, etc. -->
</rack>

Note: The A, B, C, D geometry attributes follow the EIA-310-E standard for 19-inch rack specifications. You may define your own A, B, C, and D values.

<appliance> — Equipment

Servers, switches, storage arrays, PDUs, UPS units, and any other rack-mounted equipment.

When used as a standalone document root (without a parent <rack>), an <appliance> element defines a reusable appliance library entry that can be imported into any rack.

Attribute	Type	Required	Default	Description
type	string	No	—	Appliance classification (e.g., "server", "switch", "pdu")
version	string	No	—	Schema version for this appliance definition
anchor	string	No	"front"	Mounting reference point (front / rear)
position	string	No	"mounted"	Installation position type
rot_x	decimal	No	0	Rotation around X-axis in degrees
rot_y	decimal	No	0	Rotation around Y-axis in degrees
rot_z	decimal	No	0	Rotation around Z-axis in degrees
_manufacturer	string	No	—	User-defined manufacturer (e.g., "Dell", "Cisco")
_model	string	No	—	User-defined model (e.g., "R740", "C9300-48T")
_description	string	No	—	User-defined notes

Custom attributes: Any attribute prefixed with _ is a user-defined extension field. The schema reserves _manufacturer, _model, and _description as conventions, but you can add any _-prefixed attribute. The XSD also allows attributes from other XML namespaces on all elements via xs:anyAttribute.

Child elements: <slot>, <port>, <annotation>

<appliance name="web-server-01" y="1u" type="server"
           _manufacturer="Dell" _model="R740"
           size_x="440mm" size_y="2u" size_z="800mm">
    <port name="eth1" type="rj45" x="50mm" y="0" face="front" />
    <port name="power1" type="c14" x="10mm" y="0" face="rear" />
</appliance>

<slot> — Expansion Bay

Defines a modular bay within an appliance that accepts components (PSU bays, line card slots, drive bays, PCIe slots).

Attribute	Type	Required	Description
accepts	string	Yes	Component type this slot accepts (e.g., "psu", "linecard", "pcie")
face	string	Yes	Which face of the appliance (front / rear)
rotation	decimal	No	Rotation in degrees around Z-axis

Child elements: <component> (0 or 1)

<slot name="psu-slot-1" accepts="psu" face="rear"
      x="10mm" y="10mm" size_x="100mm" size_y="50mm">
    <component type="psu" name="750w-psu">
        <port name="power-in" type="c14" x="10mm" y="10mm" />
    </component>
</slot>

<component> — Installed Module

A modular component installed in a slot — power supplies, line cards, drive modules, etc.

Attribute	Type	Required	Description
type	string	Yes	Component type classification

Child elements: <port>

<component type="linecard" name="48-port-ethernet">
    <port name="eth1" type="rj45" x="10mm" y="10mm" />
    <port name="eth2" type="rj45" x="20mm" y="10mm" />
</component>

<port> — Connection Point

A physical port on an appliance or component — network, power, console, USB, etc.

Attribute	Type	Required	Default	Description
type	string	Yes	—	Port type identifier
face	string	No	—	Which face the port is on (front / rear)
rotation	decimal	No	0	Rotation in degrees around Z-axis

Common port types:

Type	Description
rj45	Ethernet (copper)
rj45_f	Ethernet (female)
sfp	1G fiber / copper SFP
sfp+	10G fiber / DAC
qsfp	40G/100G fiber
fiber	Generic fiber port
c14	IEC C14 power inlet (equipment side)
c13	IEC C13 power outlet (PDU side)
c20	IEC C20 high-power inlet
console	Serial console port
serial	RS-232 serial port
usb	USB port
hdmi	HDMI video output
displayport	DisplayPort video output
vga	VGA video output

Implementations should accept additional type values to support new connector standards without a schema revision.

<port name="mgmt-port" type="rj45" x="380mm" y="0" face="front" />
<port name="power-in-1" type="c14" x="50mm" y="0" face="rear" />

<connection> — Cable / Link

Defines a cable or logical connection between two ports. Port references use slash-delimited path notation: appliance-name/port-name.

Attribute	Type	Required	Description
from	string	No	Source port path (e.g., "server-01/eth1")
to	string	No	Destination port path (e.g., "switch-01/port24")
cable-type	string	No	Cable medium (e.g., "Cat6", "OM4", "DAC")

<connection name="uplink-1" from="server-01/eth1" to="switch-01/port24" cable-type="Cat6" />

<annotation> — Notes

User-authored notes attached to a rack or appliance. Can be placed as a child of <rack> or <appliance>.

Attribute	Type	Required	Description
text	string	Yes	Annotation body (plain text)
author	string	No	Who wrote it
date	string	No	ISO 8601 timestamp (e.g., "2026-03-15T14:30:00Z")

<rack name="prod-rack-01" height="42">
    <annotation text="Primary production rack" author="jsmith" date="2024-01-15T10:30:00Z" />
    <appliance name="web-server" y="1u" type="server">
        <annotation text="Scheduled for replacement Q2 2024" author="ops-team" />
    </appliance>
</rack>

Design Principles

1. Dimensional accuracy — Every position and size maps to real physical measurements. No abstract grid cells.
2. Front/rear awareness — Ports and slots specify which face they're on, enabling accurate front-of-rack and rear-of-rack views.
3. Connection completeness — Both network and power cabling are first-class citizens with cable type metadata.
4. Extensibility — User-defined _-prefixed attributes let you attach any metadata without schema changes.
5. Human readability — Plain XML that engineers can read, write, and diff in version control.

File Extensions

Extension	Usage
.rml	RackML document; Preferred
.xml	Also valid; Use only when required by constraints

Contributing

Contributions are welcome. Please open an issue to discuss proposed schema changes before submitting a pull request.

License

Licensed under the Apache License 2.0.

Copyright 2024 Logistic Support Alliance

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

Trademark

"RackML" is a trademark of Logistic Support Alliance. You may use the name to refer to the schema format, but you may not use it in a way that implies official endorsement of your product or service without written permission.