Agent sandboxes / UCloud Agent Sandbox alternative

A UCloud Agent Sandbox alternative

UCloud already supports filesystem-and-memory pause, reusable full-state snapshots and independent beta Volumes. Its ordinary live rootfs is host-local, with a 24-hour continuous-running window. Compare these modes and the separately advertised service-type beta with Sandbox0’s regionally committed growing RootFS.

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Reviewed 2026-10-18 · Published by the Sandbox0 team

When UCloud Agent Sandbox fits

UCloud fits teams wanting E2B-style execution, full-state snapshots and pause/resume within its cloud. It also offers Volumes that outlive a sandbox and can be accessed without attaching compute, subject to beta enablement. These are meaningful persistence features, not merely scratch files.

When to consider Sandbox0

Consider Sandbox0 when the entire writable RootFS should grow online and recover committed state on compatible nodes, with supported paused-file access. Process continuation requires an explicit compatible experimental memory checkpoint; default pause/resume starts fresh processes.

Capabilities

UCloud Agent Sandbox and Sandbox0: what persists?

Feature comparison with documentation and verification status
Environment and runtime lifetimeUCloud Agent SandboxUp to 24 hours continuously, followed by pause/resume to reset the window; not an unbounded continuous process promise.View evidence ↗Sandbox0ttl and hard_ttl default to 0 (disabled). Configure idle pause and deletion policies for the same persistent sandbox identity; an idle running sandbox still accrues compute charges.Read documentation →
Persistent filesUCloud Agent SandboxPause/snapshots retain disk; beta Volumes persist independently. Ordinary unsaved live rootfs remains host-local.View evidence ↗Sandbox0The writable RootFS survives successful checkpoints, including software, system configuration, dependencies, and user data.Read documentation →
Whole RootFSUCloud Agent SandboxPause saves the sandbox filesystem and execution memory, beyond only a workspace mount.View evidence ↗Sandbox0Persistence extends beyond /workspace to paths such as /usr/local, /etc, and /home. Runtime tmpfs and virtual filesystems are excluded.Read documentation →
Release compute, keep stateUCloud Agent SandboxPause/resume preserves state and resets the 24-hour continuous-run window.View evidence ↗Sandbox0Pause compute between tasks; resume on available capacity. Default resume starts fresh processes from the saved filesystem.Read documentation →
Memory and process stateUCloud Agent SandboxSnapshots capture memory and filesystem; active connections can disconnect during capture.View evidence ↗Sandbox0Experimental memory checkpoints can preserve compatible process state. Use memory: true on both pause and resume on a compatible deployment. A filesystem checkpoint alone does not preserve running processes.Read documentation →

Online RootFS growth

On growth-enabled images, Sandbox0 automatically expands the writable RootFS as free space runs low, within a configured sparse logical ceiling up to 64 TiB. Agent processes keep running. Growth is enabled in the qualified Cloud region; confirm activation for other regions. Existing images and snapshots retain their captured storage geometry. The ceiling is logical capacity, not preallocated host disk.

The ordinary runtime allocates 10 GB of local disk, while durable service-type sandboxes and Volumes have separate beta access. The reviewed sources do not establish automatic online growth of an ordinary sandbox’s whole RootFS. Snapshot persistence alone is not that growth contract.

Files while compute is paused

Sandbox0's Files API reads persistent files without resuming compute. Filesystem-only pauses also permit edits; retained-memory pauses are read-only and reject mutations with 409. SSH, SFTP, file watching, and runtime-only mounts require running compute.

UCloud explicitly wakes a paused sandbox for supported file reads/writes when auto_resume is enabled. Its beta Volume API can read/write unmounted Volume files without compute; acknowledge that separate feature. Sandbox0’s paused Files API operates on persistent RootFS state, permits filesystem-only mutations and protects memory checkpoints.

See paused file operations →

Pause resets the continuous-running window

The lifecycle guide sets a 24-hour continuous-run maximum for every user. Pause/resume resets that window while preserving state; it is not a 24-hour total cap on all future returns. The default timeout is five minutes, and automatic pause must be selected to avoid ordinary timeout reclamation.

Source 1 ↗Source 2 ↗

Full-state checkpoints differ from durable live storage

Pause and snapshots retain filesystem plus memory and running processes. The source continues after snapshot capture, but streams and PTYs may disconnect during the short pause. The overview warns that an ordinary live rootfs is host-local and can be lost with host failure; a separate long-running service-type sandbox with durable rootfs and migration is an application-only beta.

Source 1 ↗Source 2 ↗Source 3 ↗

Direct Volume files are a separate beta interface

Volume storage outlives the sandbox and exposes SDK file operations without mounting any sandbox. The guide marks Volume as beta and disabled by default. These direct operations apply to a Volume’s files, while ordinary sandbox file access with auto_resume enabled wakes the paused machine.

Source 1 ↗Source 2 ↗

Pricing

Compare billing models, then price your workload

CPU allocation, memory, billing minimums, disk, plan fees, and supported workload differ. These meters are not equal-performance machine quotes. Confirm region, resource units, and included allowances before estimating a total.

UCloud Agent Sandbox

Pricing reviewed 2026-10-18

CPU
CNY ¥0.00003 per vCPU-second
Rate source ↗
Allocated RAM
CNY ¥0.000015 per GiB-second
Rate source ↗
Local runtime disk
10 GB included without a local-disk fee
Local disk is temporary; this does not make retained snapshots free.
Rate source ↗
Retained storage beyond account allowance
CNY ¥0.0005 per GB-hour
60 GB retained-storage allowance; the guide describes daily settlement but lists an hourly unit rate.
Rate source ↗
New verified-account trial
480 CPU-core-hours and 960 GiB-hours RAM, once
Valid 30 days, shared by main/subaccounts; excess usage bills the cash balance.
Rate source ↗

Keep CNY prices and the separate GB/GiB units. The quota page lists a 10 GB single-user storage limit; do not reinterpret the 60 GB retained allowance as an expanded root disk. Confirm applicable quota scope, retained-storage billing granularity and separate beta-service terms before forecasting.

Check current UCloud Agent Sandbox pricing ↗

Sandbox0

$0.015/GiB-hour compute (billed by the second at approximately $0.000004167/GiB-second), plus $0.02/GiB-month of retained incremental RootFS and memory checkpoint data. Shared base images and platform recovery retention are excluded; paused sandboxes accrue storage charges only.

Compute / GiB-hour
$0.015
Retained data / GiB-month
$0.02
Paused compute
$0.00

A 4 GiB agent, 100 running hours

$6.00 compute

4 GiB × 100 hours, billed by the second. Keeping 20 GiB of billable incremental data for a full billing month adds $0.40. CPU is derived from memory by the platform; choose a tier that fits your workload.

Understand storage billing →

Before migrating from UCloud Agent Sandbox

  1. Record timeout/auto-pause settings, completed snapshots, retained storage, Volume access and any service-type beta contract; export important live files before host loss or deletion.
  2. Port compatible images/tools and credentials, copying Volume data separately and keeping region placement and live-stream reconnect behavior in the application.
  3. Test repeated 24-hour-window transitions, process continuation needs, installed packages and RootFS growth, paused files and actual compute/retained-storage charges.

Common questions

Is Sandbox0 a drop-in UCloud Agent Sandbox replacement?

Evaluate API compatibility and product scope. A shared sandbox category does not make SDKs, lifecycle semantics, or limits interchangeable.

Does keeping files also keep a running agent?

Filesystem state and volatile process state are separate. Sandbox0 requires explicit compatible memory checkpoints to preserve running processes; its default filesystem resume starts fresh processes.

Sources and review scope

The Boat team's Battleships directory is the discovery source. References below describe the product and plan discussed on this page. Check current availability, regional terms and billing units before migrating. Where the cited material does not establish a capability or price, the comparison identifies that uncertainty.

Battleships research record ↗astraflow.ucloud.cn/docs/agent-sandbox/sandbox/lifecycle.md ↗astraflow.ucloud.cn/docs/agent-sandbox/sandbox/persistence.md ↗astraflow.ucloud.cn/docs/agent-sandbox/sandbox/snapshots.md ↗astraflow.ucloud.cn/docs/agent-sandbox.md ↗astraflow.ucloud.cn/docs/agent-sandbox/storage/volume/overview.md ↗astraflow.ucloud.cn/docs/agent-sandbox/sandbox/auto-resume.md ↗astraflow.ucloud.cn/docs/agent-sandbox/product/fee.md ↗Sandbox0 RootFS capacity →

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