Buying a server for a business quickly raises many questions: should it be a rack or tower model? How many Xeon cores? What level of RAID? How much RAM? And is the tested used server reliable? This guide provides the benchmarks to choose a server suited to your needs—virtualization, file sharing, backup—without paying the price of new equipment.
Rack server or tower server: which to choose?
The tower server looks like a large PC: ideal for a small or medium business without a dedicated server room, quiet, and easy to place in an office. The rack server (1U, 2U format, etc.) mounts in a 19-inch rack: it optimizes space, allows neat cabling, and stacks with other equipment. Once you have a rack or multiple servers, the rack format is essential. For rack hosting, also consider network chassis and racks.
The processor: Xeon, cores, and generations
Servers rely on Intel Xeon processors (or AMD EPYC), designed to run 24/7 and handle many cores. For virtualization, the number of cores/threads and amount of RAM matter more than pure frequency. A dual-processor server (two sockets) multiplies capacity to host multiple virtual machines. Check the Xeon generation: a recent generation offers better energy efficiency.
Memory: ECC RAM
A server uses ECC RAM (error-correcting), often registered (RDIMM)—essential for the stability of a system that never shuts down. Plan generously: RAM is the primary limiting factor in virtualization. Memory and other parts can be found in our server components.
Storage and RAID
RAID combines multiple drives for performance and/or data security:
- RAID 1 (mirror): two identical drives, tolerates one drive failure. Simple and safe.
- RAID 5: distribution + parity on at least 3 drives, a good balance of capacity/security (tolerates 1 failure).
- RAID 6: like RAID 5 but tolerates 2 simultaneous failures.
- RAID 10: mirror + striping, high performance and security (minimum 4 drives).
- RAID 0: pure performance, no fault tolerance—reserved for non-critical data.
RAID is managed by a dedicated controller (e.g., PERC for Dell). For drives, choose SAS (robust, server-grade), SATA (high capacity), or SSD/NVMe (fast)—see our hard drives & SSDs and, for large volumes, network storage arrays. Important: RAID is not a backup—it protects against hardware failure, not deletion or ransomware.
Points to check before buying
- Redundant power supplies (two units) to avoid outages if one fails.
- RAID controller present and compatible with your drives.
- Remote management: iDRAC (Dell), iLO (HPE), IPMI—very useful for administration without a monitor.
- Hot-swap bays: replace a drive without shutting down.
- Format and number of bays suited to your data volume.
Which server for which use?
- Virtualization (VMware, Proxmox, Hyper-V) → many cores and RAM, RAID 10 or 5.
- File server / Active Directory → balanced configuration, RAID 1 or 5.
- Backup / archiving → large disk capacity, possibly combined with LTO tape backup.
Used server: the best value for money
A professional server is designed for years of continuous operation: tested used servers remain perfectly reliable for a fraction of the new price. Proven ranges like Dell PowerEdge servers are safe bets. Browse all our used rack and tower servers, and for general context, our used IT equipment guide.
FAQ: choosing a server
Rack or tower server for an SME?
A tower is sufficient and suitable without a server room. Once you have a 19” rack or plan multiple servers, the rack format is more practical.
How much RAM for virtualization?
RAM is the primary limiting factor: budget generously based on the number and size of virtual machines, and prioritize ECC RAM. It’s better to have extra capacity from the start.
Which RAID level to choose?
RAID 1 for a small server, RAID 5 for a good balance of capacity/security, RAID 10 for performance. Reminder: RAID does not replace a backup.
Is a used server reliable?
Yes, if it is tested and guaranteed. Server hardware is designed for very long service life; a model a few years old is far from end-of-life.
In summary
To choose a server well: determine the format (rack/tower), power (Xeon cores + ECC RAM), storage and RAID level according to your data, then check reliability features (redundant power, remote management, hot-swap). With tested used equipment, you get reliable professional hardware at a controlled cost.