On a shared Plesk server, one busy or badly coded site can consume disk, traffic, CPU or memory meant for everyone. Plesk tracks usage per subscription and lets you decide what happens when limits are reached, from a polite email to suspension. Its Resource Controller extension adds CPU and memory limits.
Before you start
- Plesk administrator access.
- Service plans with defined limits; see service plans and subscriptions.
Check usage
- Subscriptions list: sort by disk or traffic columns to find the heaviest users.
- Open a subscription and view Statistics or Account → Resource Usage for disk by category (web, mail, databases, logs, backups) and monthly traffic.
- Customers see the same information on their own dashboard.
Plesk recalculates statistics daily. Run plesk daily or /usr/local/psa/admin/sbin/statistics --calculate-one --domain-name=example.com for an immediate update.
Choose the overuse policy
On a service plan (or a subscription's customised settings), open Resources and choose Overuse policy:
- Not allowed – the subscription is suspended when a limit is exceeded. Strict and predictable, but surprises customers.
- Allowed (with notification) – usage may exceed the limit, and Plesk notifies you and the customer.
- Allowed (without notification) – limits act as information only.
Disk quotas can additionally be enforced as hard quotas at the file system level, so writes fail when the quota is full. Enable them only if your file system supports quotas and customers understand the effect.
Notifications
Go to Tools & Settings → Notifications. Enable messages such as Resource usage limits exceeded by subscription and Subscription expiration, choose recipients (administrator, reseller, customer) and edit the text. Warning customers early lets them clean up or upgrade before anything breaks.
CPU, memory and I/O limits
- Install the Resource Controller extension from Extensions → Extensions Catalog (it uses Linux cgroups).
- Set default limits for CPU percentage, RAM and disk I/O per subscription in the service plan's Resources tab.
- Choose actions on overuse: throttle and notify.
This prevents a single site from making the whole server slow. CloudLinux offers similar, more advanced limits if you run it with Plesk.
Reduce disk usage
- Rotate and compress logs under the domain's Logs → Log Rotation; see Log Browser.
- Store backups remotely instead of on the server.
- Delete old staging copies and unused mailboxes.
Troubleshooting
- Usage numbers outdated: statistics run daily; trigger a recalculation.
- Subscription suspended unexpectedly: overuse is not allowed and a limit was hit; raise the limit or clean up, then activate it.
- Site slow with Resource Controller: limits too tight; check its statistics and adjust.