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Rack-Server
In data centers and server rooms, most servers are stacked flat on top of each other in cabinets. This form factor is called a rack server. Anyone decommissioning servers should know their structure, because data is not only on the visible hard drives. This entry explains dimensions, structure and differences from other form factors.
In brief
A rack server is a server in a flat chassis that is slid into and screwed onto a standardized 19-inch rack. Its height is stated in rack units (U), one rack unit corresponding to 44.45 millimeters. When decommissioning, besides the hard drives, boot media, RAID controllers and the remote management chip also matter, because data and credentials can be stored there as well.
Structure of a rack server
A 19-inch rack is a standardized cabinet into which servers, storage systems and network components are installed on top of each other. Rack servers are usually 1U, 2U or 4U high and run on rails so that they can be pulled out for maintenance. Typical components are:
- Drive bays: Hard drives or SSDs sit in caddies at the front and can be replaced during operation. They are connected via SATA, SAS or NVMe.
- RAID controller: It distributes data across several drives, see RAID.
- Redundant power supplies and fans for continuous operation.
- Internal boot media: Small SSDs in M.2 format, memory cards or internal USB sticks on which the operating system resides.
- Remote management controller (BMC): A dedicated chip with a network connection through which administrators control the server remotely. It stores configuration, user accounts and logs.
Rack, tower and blade servers compared
| Form factor | Characteristics | Typical use |
|---|---|---|
| Tower server | Stands freely like a PC, plenty of space for expansion, quieter | Small offices without a server room |
| Rack server | Flat, in a 19-inch rack, high density, good serviceability | Server rooms and data centers |
| Blade server | Very flat plug-in modules in a shared chassis with shared power supply and networking | Large environments with many similar servers |
What to note when retiring devices
A rack server often contains many data carriers. Each one must be recorded and erased or destroyed, even if it contains only parts of a RAID array. The internal boot media and the remote management controller, which can store passwords, network data and certificates, are frequently forgotten. Reset it to factory settings or have this done as part of the erasure. When dismantling entire server rooms, this is referred to as Data center decommissioning.
Whether a rack server still has a Residual value depends mainly on processor generation, memory, drives and completeness. How the sale works is explained in our guide Selling used servers: First the data, then the money.
Rule of thumb: A server has more data carriers than you can see from the front – boot media and remote management controllers belong on every checklist.
Rack servers and Second IT
Second IT buys servers and data center equipment and collects them with its own secure logistics. At goods receipt, every device is checked for all storage media, including hidden hard drives in old server chassis, and registered by serial number. Erasure is performed with Blancco, with an erasure report per serial number; drives that cannot be erased are destroyed in-house in accordance with DIN 66399 (up to security level H-5 and E-5). More on inventory analysis and market valuation.
Frequently asked questions about rack servers
How tall is a rack unit?
One rack unit (U) measures 1.75 inches, that is 44.45 millimeters. A 2U server is therefore just under 9 centimeters tall. The width of the front panel in 19-inch technology is 482.6 millimeters.
Do RAID hard drives have to be erased individually?
Yes. Even a single hard drive from a RAID array can contain readable data fragments. Each drive should therefore be erased individually and documented with its serial number, or destroyed.
What is the difference between a server rack and a rack server?
The server rack is the cabinet into which devices are installed. The rack server is the device itself. Besides servers, a rack often also holds storage systems, switches and power distribution units.
Which data carriers are in a rack server besides the hard drives?
Internal boot media such as small M.2 SSDs, memory cards or internal USB sticks. In addition there are RAID controllers and the remote management controller (BMC), which stores configuration, user accounts and logs. All of them belong on the checklist when decommissioning.
Does a used rack server still have a residual value?
Often yes. The residual value depends mainly on processor generation, memory, drives and completeness. Before the sale, all data carriers must be erased and documented. A precise device list with serial numbers makes the assessment easier.
Decommission servers – with an erasure certificate for every drive.
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