The hardware behind xsubi is a pair of Dell PowerEdge R720 rack servers, pulled from data center service after their 3-5 year depreciation cycle. These aren't consumer machines — they're enterprise-grade systems designed for 24/7 operation in temperature-controlled environments. And they cost less than a gaming PC.
Specifications. Each R720 runs dual Intel Xeon E5-2600 series processors (up to 16 cores / 32 threads per CPU), 128-384 GB of DDR3 ECC RAM, and 8 hot-swap 3.5" drive bays with PERC RAID controllers. The chassis includes redundant 750W power supplies, iDRAC for out-of-band management, and 4x 1GbE network ports. These are the same servers that ran Fortune 500 workloads.
Economics. A fully loaded R720 costs $200-400 on eBay. Compare that to a single month of equivalent cloud compute on AWS. The upfront investment pays for itself in 2-3 months of what you'd spend on EC2 instances with comparable specs. After that, you're paying only for electricity (~$30-50/month per server) and internet.
KVM on Linux. The primary hypervisor runs Ubuntu Server with KVM/libvirt. KVM is a Type 1 hypervisor built into the Linux kernel — no extra software layer, no licensing fees, near-native performance. Each VM gets a defined allocation of CPU, RAM, and disk, managed through libvirt's API. The xsubi host agent talks to libvirt directly.
Hyper-V on Windows Server. The secondary hypervisor runs Windows Server 2022 Datacenter. Hyper-V handles Windows-specific workloads — Active Directory, SQL Server, .NET applications. Having both KVM and Hyper-V means xsubi can offer Linux and Windows VMs without compromise.
Lessons learned. Enterprise hardware is built differently. ECC RAM catches bit-flip errors silently. Hot-swap drives mean zero downtime for disk replacement. IPMI/iDRAC lets you reboot a server from your phone. These aren't luxury features — they're the baseline for reliable hosting. Consumer hardware doesn't have them.