Amulet vs JuiceFS
JuiceFS is an excellent general-purpose distributed filesystem — mature, POSIX-complete, and self-hostable, provided you operate its metadata database, cache tier, and object-store layout yourself. Amulet trades that generality for the agent workload: zero operations, workspace forks that copy nothing, commit history with provenance, and publishes that can't silently overwrite another agent's work. Teams that need a general shared POSIX filesystem and have the ops capacity should consider JuiceFS; teams giving fleets of agents isolated, versioned working copies should use Amulet.
Amulet
Amulet is a managed file system for parallel AI workloads: workspaces mount in under 100 ms, fork instantly without copying data, and keep a versioned, attributable history of every change.
JuiceFS
JuiceFS is an open-source distributed POSIX filesystem that stores data in object storage and metadata in a database you choose, deploy, and operate.
Capability by capability
Capability
Amulet
JuiceFS
Managed service
Amulet
Yes
Fully managed — no metadata database, cache tier, or object-store layout to run.
JuiceFS
Partial
Community edition is self-hosted (you operate Redis/MySQL/TiKV metadata and caching); a separate enterprise offering exists.
Mount latency
Amulet
Yes
Under 100 ms, independent of workspace size.
JuiceFS
Yes
Fast mounts once the metadata service is reachable.
Instant copy-on-write forks
Amulet
Yes
Fork a workspace in milliseconds; zero bytes copied until writes diverge.
JuiceFS
Partial
Directory-level clone exists as a metadata copy within one filesystem; not an isolated writable workspace with its own publish semantics.
Version history
Amulet
Yes
Content-addressed commits capture full workspace state; restore any revision exactly.
JuiceFS
No
Snapshots of current state are possible operationally, but there is no first-class commit history.
Conflict-safe publishing
Amulet
Yes
Compare-and-swap publishes; stale writers get an explicit conflict, never silent overwrites.
JuiceFS
No
Standard shared-filesystem semantics — concurrent writers coordinate themselves.
Provenance
Amulet
Yes
Every commit records the actor, session, and run that produced it.
JuiceFS
No
No per-change attribution beyond filesystem metadata and access logs.
POSIX coverage
Amulet
Partial
Covers the file workflows agent and training jobs run — Git, grep, jq, build tools. Live same-file multi-writer access is excluded by design.
JuiceFS
Yes
Near-complete POSIX compatibility, including shared multi-client writes and locks.
Performance
Amulet
Yes
8.4 GB/s sustained per mount, p99 reads of 1.9 ms, forks in 3 ms.
JuiceFS
Yes
Strong cached throughput and metadata performance when well-tuned; results depend on your metadata engine and cache deployment.
Credential model
Amulet
Yes
Agents receive short-lived, workspace-scoped grants; object-store credentials never enter the agent process.
JuiceFS
Partial
Clients need connectivity and credentials for the metadata service; object-store credentials sit with the deployment.
Deduplication
Amulet
Yes
Identical file bytes are stored once per account; forks share unchanged data.
JuiceFS
No
Block storage layout without content-addressed dedup.
Operational burden
Amulet
Yes
None — provision a workspace through an API and mount.
JuiceFS
No
You run and scale the metadata database, plan capacity, and manage upgrades and backups.
Pricing
Amulet
Yes
$0.20/GiB-month for actively used data; API, transfers, and metadata free; 10 GB free tier.
JuiceFS
Partial
Open-source software is free; you pay for object storage, the metadata database, cache infrastructure, and the time to run them.
When to choose JuiceFS
- You need a general-purpose shared POSIX filesystem — including multi-client same-file writes and locks — beyond agent and training workflows.
- You want full control of your storage stack, self-host by policy, and have the capacity to operate a metadata database and cache tier.
- You already run JuiceFS in production and its semantics fit your workload.
When to choose Amulet
- You want workspace forks, history, and attribution as product primitives rather than operational projects.
- Fleets of agents or parallel experiments need isolated working copies of shared data, created instantly and merged deliberately.
- You don't want to run a metadata database to give jobs a filesystem.
- Agents should never hold long-lived storage credentials.
Frequently asked questions
Is Amulet a JuiceFS replacement?
For agent and parallel-AI workloads, yes — Amulet provides the mounted-filesystem ergonomics those jobs need, plus instant forks, versioned history, and conflict-safe publishing that JuiceFS does not have. For general-purpose shared POSIX storage with live multi-client same-file writes, JuiceFS remains the more complete filesystem.
Is JuiceFS faster than Amulet?
A well-tuned JuiceFS deployment sets a high bar for warm reads and cached metadata, and honest comparisons depend on the exact workload and deployment. Amulet targets the same class of warm-read performance while adding operations JuiceFS doesn't have at any speed: forking a workspace in milliseconds with zero bytes copied, and publishing with conflict detection.
Do I still need object storage with Amulet?
No separate setup is required. Amulet manages durable, S3-compatible object storage as the backing layer, so a workspace is a single API call — there is no bucket layout, metadata database, or cache tier to design.
What does JuiceFS actually cost to run?
The software is open source, but a production deployment pays for object storage, a highly available metadata database (Redis, MySQL, or TiKV), cache disks, and the engineering time to operate them. Amulet's pricing is a single number: $0.20 per GiB-month of actively used data, with a 10 GB free tier.