Cloud Storage FUSE (original) (raw)

This document provides an overview of Cloud Storage FUSE, a FUSEadapter that lets you mount and access Cloud Storage buckets as local file systems, so applications can read and write objects in your bucket using standard file system semantics.

This documentation always reflects the latest version of Cloud Storage FUSE. For details on the latest version, seeCloud Storage FUSE releases on GitHub.

Cloud Storage FUSE is an open source product supported by Google. Cloud Storage FUSE uses FUSE and Cloud Storage APIs to transparently expose buckets as locally mounted folders on your file system.

To use Cloud Storage FUSE, you install the Cloud Storage FUSE package on a machine with a compatible operating system such as Linux or Windows Subsystem for Linux, ensure proper Google Cloud authentication and permissions, and then execute the gcsfuse command to mount a specific Cloud Storage bucket to a local directory.

Cloud Storage FUSE is integrated with other Google Cloud services. For example, the Cloud Storage FUSE CSI driver lets you use the Google Kubernetes Engine (GKE) API toconsume buckets as volumes, so you can read from and write to Cloud Storage from within your Kubernetes pods. For more information on other integrations, see Integrations.

How Cloud Storage FUSE works

Cloud Storage FUSE works by translating object storage names into a directory-like structure, interpreting the slash character (/) in object names as a directory separator. Objects with the same common prefix are treated as files in the same directory, allowing applications to interact with the mounted bucket like a file system. Objects can also be organized into a logical file system structure using hierarchical namespace, which lets you organize objects into folders.

Cloud Storage FUSE can be run from anywhere with connectivity to Cloud Storage, including Google Kubernetes Engine, Compute Engine VMs, or on-premises systems.

Cloud Storage FUSE for machine learning

Cloud Storage FUSE is ideal for use cases where Cloud Storage has the right performance and scalability characteristics for an application that requires file system semantics. For example, Cloud Storage FUSE isuseful for machine learning (ML) projects because it provides a way to store data, models, checkpoints, and logs directly in Cloud Storage. For more information, see Cloud Storage FUSE for ML workloads.

Cloud Storage FUSE is a common choice for developers looking to store and access ML training and model data as objects in Cloud Storage. Cloud Storage FUSE provides several benefits for developing ML projects:

• Cloud Storage FUSE lets you mount Cloud Storage buckets as a local file system so your applications can access training and model data using standard file system semantics. This means that you can avoid the cost of rewriting or refactoring your application's code when using Cloud Storage to store ML data.
• From training to inference, Cloud Storage FUSE lets you use the built-in high scalability, performance, and cost effectiveness of Cloud Storage, so you can run your ML workloads at scale.
• Cloud Storage FUSE lets you start training jobs quickly by providing compute resources with direct access to data in Cloud Storage, so you don't need to download training data to the compute resource.

For more information, seeFrameworks, operating systems, and architectures supported by Cloud Storage FUSE.

Frameworks, operating systems, and architectures

Cloud Storage FUSE has been validated with the following frameworks:

• TensorFlow V2.x
• TensorFlow V1.x
• PyTorch V2.x
• PyTorch V1.x
• JAX 0.4.x

Cloud Storage FUSE supports the following operating systems and architectures:

• Rocky Linux 8.9 or later
• Ubuntu 18.04 or later
• Debian 10 or later
• CentOS 7.9 or later
• RHEL 7.9 or later
• SLES 15 or later
• x86_64
• ARM64

Integrations with other Google Cloud products

Cloud Storage FUSE integrates with the following Google Cloud products:

For a list of Google Cloud products that are integrated with Cloud Storage generally, see Integration with Google Cloud services and tools.

Caching

Cloud Storage FUSE offers four types of caching to help increase performance and reduce cost: file caching, stat caching, type caching, and list caching. For more information about these caches, see Overview of caching.

Directory semantics

Cloud Storage offers buckets with a flat namespace and buckets with hierarchical namespace enabled. By default, Cloud Storage FUSE can infer explicitly-defined directories, also known as folders, in buckets with hierarchical namespace enabled but it can't infer implicitly-defined directories in buckets with a flat namespace, includingsimulated folders and managed folders.

Explicitly defined directories are folders that are represented by their own objects in Cloud Storage buckets.Implicitly defined directories are directories that don't have their own corresponding objects in Cloud Storage buckets.

For example, say you mount a bucket named my-bucket, which contains an object named my-directory/my-object.txt, where my-directory/ is a simulated folder. When you run ls on the bucket mount point, by default, Cloud Storage FUSE cannot access the simulated directory my-bucket/my-directory/ nor the objectmy-object.txt within it. To enable Cloud Storage FUSE to infer the simulated folder and the object within it, include the--implicit-dirs gcsfuse option or theimplicit-dirs configuration file field as part of your gcsfuse mountcommand when mounting a flat namespace bucket.

If you need to store and access your data using a file system, use buckets with hierarchical namespace enabled. To learn how to create such buckets, seeCreate buckets with hierarchical namespace enabled.

For more information about directory semantics, including how to mount buckets with implicitly-defined directories, seeFiles and directories in the Cloud Storage FUSE GitHub documentation.

Cloud Storage FUSE retry strategies

By default, failed requests from Cloud Storage FUSE to Cloud Storage areretried with exponential backoff up to a specified maximum backoff duration, which has a value of 30s (30 seconds) by default. Once the backoff duration exceeds the specified maximum duration, the retry continues with the specified maximum duration. You can use the--max-retry-sleep option or thegcs-retries:max-retry-sleep field as part of a gcsfuse mount call to specify the backoff duration.

Retry strategy for stalled GET or READ requests

When you perform a GET or READ request with Cloud Storage FUSE, a timeout period is applied. If the request exceeds the timeout period, Cloud Storage FUSE cancels the request and retries using an exponential backoff algorithm.

The timeout is dynamic and is based on the 99th percentile latency of past successful or canceled GET or READ requests, with a 1.5-second minimum. This ensures that only the slowest 1% of requests, those exceeding the 99th percentile historical latency, are retried.

Retry strategy for stalled uploads

Large file writes are uploaded in chunks. To help reduce tail end write latencies, if a chunk-level write operation stalls or fails, Cloud Storage FUSE attempts a retry after 10 seconds. A maximum of four retry operations are performed for each stalled chunk.

Cloud Storage FUSE operations associated with Cloud Storage operations

When you perform an operation using Cloud Storage FUSE, you also perform the Cloud Storage operations associated with the Cloud Storage FUSE operation. The following table describes common Cloud Storage FUSE commands and their associated Cloud Storage JSON API operations. You can display information about the Cloud Storage FUSE operations by setting the--log-severity option or thelogging:severity field to TRACE in your gcsfuse command.

Metrics

Cloud Storage offers in-depth metrics which can help you optimize Cloud Storage FUSE performance and costs. To learn more about metrics for Cloud Storage FUSE, see Cloud Storage FUSE Metrics.

Security

Cloud Storage FUSE applies Google Cloud's standard authentication throughApplication Default Credentials to identify users or service accounts. Access to the contents within buckets is governed by Identity and Access Managementpermissions. Local system permissions secure the mount point itself and any locally cached data.

Pricing for Cloud Storage FUSE

Cloud Storage FUSE is available free of charge, but the storage, metadata, and network I/O it generates to and from Cloud Storage are charged like any other Cloud Storage interface. In other words, all data transfer and operations performed by Cloud Storage FUSE map to Cloud Storage transfers and operations, and are charged accordingly. For more information on common Cloud Storage FUSE operations and how they map to Cloud Storage operations, see operations mapping.

To avoid surprises, you should estimate how your use of Cloud Storage FUSE translates to Cloud Storage charges. For example, if you are using Cloud Storage FUSE to store log files, you can incur charges quickly if logs are aggressively flushed on hundreds or thousands of machines at the same time.

See Cloud Storage pricing for information on charges such as storage, network usage, and operations.

Limitations

While Cloud Storage FUSE has a file system interface, it is not like an NFS or CIFS file system on the backend. Additionally, Cloud Storage FUSE is not POSIX compliant. For a POSIX file system product in Google Cloud, seeFilestore.

When using Cloud Storage FUSE, be aware of its limitations and semantics, which are different than that of POSIX file systems. Cloud Storage FUSE should only be used within its capabilities.

Limitations and differences from POSIX file systems

The following list describes the limitations of Cloud Storage FUSE:

• Metadata: Cloud Storage FUSE does not transfer object metadata when uploading files to Cloud Storage, with the exception of mtime and symlink targets. This means that you cannot set object metadata when you upload files using Cloud Storage FUSE. If you need to preserve object metadata, consider uploading files using theGoogle Cloud CLI, the JSON API, or theGoogle Cloud console.
• Concurrency: when you configure multiple mount points to access the same Cloud Storage bucket, and two or more mounts attempt to write to the same Cloud Storage object simultaneously, the first mount to complete the write operation and successfully flush its changes to the object is saved. Other mounts that haven't updated their local file descriptors after the object is modified encounter a syscall.ESTALE error when attempting to save their edits due to precondition checks. To ensure that your data is consistently written, we strongly recommend against multiple sources modifying the same object.
  Note that multiple readers can access the same or different objects within a bucket, and multiple writers can modify different objects in the same bucket simultaneously. Concurrent writes to the same Cloud Storage object are supported from the same mount and behave similarly to built-in file systems.
• Linking: Cloud Storage FUSE does not support hard links.
• File locking and file patching: Cloud Storage FUSE does not support file locking or file patching. As such, you shouldn't store version control system repositories in Cloud Storage FUSE mount points, as version control systems rely on file locking and patching. Additionally, you shouldn't use Cloud Storage FUSE as a file replacement.
• Semantics: semantics in Cloud Storage FUSE are different from semantics in a conventional file system. For example, metadata like last access time are not supported, and some metadata operations like directory renaming are not atomic unless you use buckets withhierarchical namespace enabled. For a list of differences between Cloud Storage FUSE semantics and conventional file system semantics, seeCloud Storage FUSE semanticsin the Cloud Storage FUSE GitHub documentation. To learn about how Cloud Storage FUSE infers directories in Cloud Storage, seedirectory semantics.
• Workloads that do file patching (or overwrites in place): Cloud Storage FUSE can only write whole objects at a time to Cloud Storage and does not provide a mechanism for patching. If you try to patch a file, Cloud Storage FUSE will reupload the entire file. The only exception to this behavior is that you can append content to the end of a file that's 2 MB and larger, where Cloud Storage FUSE will only reupload the appended content.
• Access: authorization for files is governed by Cloud Storage permissions. POSIX-style access control does not work.
• Performance: Cloud Storage FUSE has much higher latency than a local file system, and as such, shouldn't be used as the backend for storing a database. Throughput may be reduced when reading or writing one small file at a time. Using larger files or transferring multiple files at a time will help increase throughput.
• Availability: transient errors can sometimes occur when you use Cloud Storage FUSE to access Cloud Storage. It's recommended that you retry failed operations usingretry strategies.
• Object versioning: Cloud Storage FUSE does not formally support usage with buckets that have object versioning enabled. Attempting to use Cloud Storage FUSE with buckets that have object versioning enabled can produce unpredictable behavior.
• File transcoding:
  objects with content-encoding: gzip in metadata: Any such object in a Cloud Storage FUSE-mounted directory does not undergo decompressive transcoding. Instead, the object remains compressed in the same manner that it's stored in the bucket.
  For example, a file of 1000 bytes, uploaded to a bucket using thegcloud storage cp command with the--gzip-local flag, might become 60 bytes (the actual compressed size depends on the content and the gzip implementation used by the gcloud CLI) as a Cloud Storage object. If the bucket is mounted using `gcsfuse`, and the corresponding file is listed or read from the mount directory, its size is returned as 60 bytes, and its contents are a compressed version of the original 1000 bytes content.
  This is in contrast to a download usinggcloud storage cp gs://bucket/path /local/path which undergoes decompressive transcoding: in the gcloud command, the content is auto-decompressed during the download, and the original, uncompressed content is served.
• Retention policies: Cloud Storage FUSE does not support writing to buckets with aretention policy. If you attempt to write to a bucket with a retention policy, your writes will fail.
  Cloud Storage FUSE supports reading objects from buckets with a retention policy, but the bucket must be mounted as Read-Only by passing the-o RO flag during bucket mounting.
• Local storage: objects that are new or modified are stored in their entirety in a local temporary file until they are closed or synced. When working with large files, make sure you have enough local storage capacity for temporary copies of the files, particularly if you are working withCompute Engine instances. For more information, see theCloud Storage FUSE README overview file in the Cloud Storage FUSE GitHub documentation.
• File handle limits: the Linux kernel has a default limit of 1,024 open file handles. When using Cloud Storage FUSE as a server to handle multiple concurrent connections, you might exceed this limit. To avoid issues, ensure the number of concurrent connections to a single host remains under the limit, and consider increasing the limit. Scenarios where this is important include using a Cloud Storage FUSE mount to serve web content, host network-attached storage (NAS), or host a file transfer protocol (FTP) server. When serving web content on Cloud Run from a Cloud Storage FUSE mount, themaximum concurrent requests per instanceis restricted to less than 1,000.
• rsync limitations: Cloud Storage FUSE's file system latency affects rsync, which reads and writes only one file at a time. To transfer multiple files to or from your bucket in parallel, use the Google Cloud CLIby running gcloud storage rsync. For more information, see thersync documentation.
• List operations limitations: when you list all the objects in a mounted bucket, for example, by running ls, Cloud Storage FUSE calls theObjects: list APIon Cloud Storage. The API paginates results, which means that Cloud Storage FUSE might need to issue multiple calls, depending on how many objects are in your bucket, which can make a list operation expensive and slow.

Known issues

For a list of known issues in Cloud Storage FUSE, see theopen Cloud Storage FUSE issues in GitHub.

Get support

You can get support, submit general questions, and request new features by using one of Google Cloud's official support channels. You can also get support by filing issues in GitHub.

For solutions to commonly-encountered issues, seeTroubleshooting for production issues in the Cloud Storage FUSE GitHub documentation.

What's next

• Learn how to install the Cloud Storage FUSE CLI.
• Discover Cloud Storage FUSE by completing a quickstart.
• Learn how to mount buckets.
• Learn how to configure the behavior of Cloud Storage FUSE, using thegcsfuse CLI or a Cloud Storage FUSE configuration file.