Project host storage, backups, and snapshots

What the Storage tab is for

The host Storage tab is where you inspect provider disk capacity, storage mode, usage, reservations, and host-level storage actions. It is the right place to check before growing a disk, moving projects onto a host, draining a host, or changing infrastructure that could affect local project data.

Project host storage is not the same thing as a project backup. The host disk is where running project files live. Project backups are the portable recovery copy that CoCalc can use when moving or restoring projects.

Persistent and ephemeral storage

Persistent storage is designed to survive ordinary host restarts and provider machine replacement according to the provider's disk model. Ephemeral or local storage is faster or cheaper for some workloads, but it should be treated as recoverable only through project backups and explicit project data copies.

Before placing important projects on a host, check whether the host uses persistent storage, ephemeral storage, or provider-specific attached disks. Do not assume that files outside the project backup path, such as temporary files, will survive deprovision, move, or provider replacement.

Shared scratch disks are a separate host-scoped storage feature. They are mounted at /scratch in projects on the host, shared by those projects, and not included in project backups or project moves. Use the Shared scratch disks docs before enabling scratch for a host with multiple users or projects.

Growing disk

For provisioned GCP and Nebius hosts using persistent storage, disk enlarge supports online growth. Ephemeral storage cannot be resized this way. Growing disk is one-way: plan for future use, but do not treat it as a reversible experiment.

After growing disk, verify both the provider disk size and usable filesystem capacity in the Storage tab. If the provider resize succeeds but filesystem growth reports a warning, follow its recovery instructions and verify the capacity again. Also check the host status. If usage remains high, check whether projects are producing temporary files, caches, datasets, or build artifacts that should be moved or deleted instead of simply growing the disk again.

Backups and snapshots

Use project backups for portable project recovery, cross-host moves, and protection before lifecycle actions. Use provider snapshots or host-local snapshots only when the UI or provider explicitly exposes that workflow for the host; they are infrastructure recovery tools, not a substitute for project backups.

Before deprovisioning, deleting, moving, or changing storage mode, make sure important projects have current backups. If a project has changed region, verify that a backup exists in the destination backup region after the move completes.

Agent notes

When diagnosing storage or advising a lifecycle action:

1. Open the host Storage tab for the selected host.
2. Check storage mode, provider, disk size, current usage, and whether online grow is supported.
3. Distinguish host disk state from project backup state.
4. Before deprovision, delete, region move, or storage-mode change, verify project backup freshness and assigned projects.
5. Warn explicitly that /tmp, caches, host-local snapshots, and files outside the project backup model may not follow a project move.