Virtualizor resource limits decide whether one busy customer slows everyone else on a server. Setting sensible CPU, network and disk limits in your plans, and deciding how far to oversell, keeps performance predictable.
Before you start
- Virtualizor admin access and an understanding of your plans (create plans).
- Monitoring data for your servers (resource monitoring).
Limits you can set in plans
| Setting | What it controls |
|---|---|
| CPU cores | Number of vCPUs the VPS sees |
| CPU units / weight | Relative share when CPUs are busy; higher gets more |
| CPU % limit | Hard cap on CPU use, so one VPS cannot take a full core |
| Network speed | Upload and download speed caps |
| Bandwidth | Monthly traffic allowance |
| Disk I/O limits | Read/write speed or IOPS caps, where supported |
Exact field names vary by version and virtualisation type; check the plan form for KVM.
Overselling CPU and RAM
- CPU: moderate overselling is normal because most VPSs are idle most of the time. Watch CPU steal time inside VPSs and stop adding servers when it rises.
- RAM: KVM guests really use the memory they are given. Overselling RAM risks host swapping, which slows every VPS. Keep total allocated RAM below physical RAM minus host overhead.
- Disk: thin provisioning allows overselling disk, but a full pool can freeze VPSs. Watch free space closely (LVM-thin storage).
Warning: Overselling is a business decision with real risks. Be honest in your plan descriptions and terms about what is guaranteed.
Find noisy neighbours
- Sort VPSs by CPU, bandwidth or I/O in the admin panel's monitoring views.
- On the host, confirm with
top,iotopandvirsh domstats. - Contact the customer, apply a stricter limit, or move them to a larger plan or dedicated resources.
Check afterwards
- Benchmark a test VPS before and after limits change.
- Watch host load and steal time over a week.
Troubleshooting
- Customers report slowness but limits look fine: the host disk is often the bottleneck (slow VPS troubleshooting).
- Limit change has no effect: some changes need the VPS to be restarted from the panel.
Frequently asked questions
What is a safe CPU overselling ratio?
It depends on workloads; start conservatively and use steal time and load data to decide.
Should I limit disk I/O?
Yes, a reasonable cap stops one backup or database import from slowing a whole node.
Can I offer dedicated CPU plans?
Yes, by not overselling those servers and pinning or reserving cores for them.