Availability and durability of EFS file systems

This section describes the file system types and storage class options for Amazon Elastic File System (Amazon EFS) file systems.

EFS file system types

Amazon EFS offers Regional and One Zone file system types.

• Regional – Regional file systems (recommended) store data redundantly across multiple geographically separated Availability Zones within the same AWS Region. Storing data across multiple Availability Zones provides continuous availability to the data, even when one or more Availability Zones in an AWS Region are unavailable.

• One Zone – One Zone file systems store data within a single Availability Zone. Storing data in a single Availability Zone provides continuous availability to the data. In the unlikely case of the loss or damage to all or part of the Availability Zone, however, data that is stored in these types of file systems might be lost.

  In the unlikely case of the loss or damage to all or part of an AWS Availability Zone, data in a One Zone storage class may be lost. For example, events like fire and water damage could result in data loss. Apart from these types of events, our One Zone storage classes use similar engineering designs as our Regional storage classes to protect objects from independent disk, host, and rack-level failures, and each are designed to deliver 99.999999999% data durability.

  For added data protection, Amazon EFS automatically backs up One Zone file systems with AWS Backup. You can restore file system backups to any operational Availability Zone within an AWS Region, or you can restore them to a different AWS Region. EFS file system backups that are created and managed using AWS Backup are replicated to three Availability Zones and are designed for durability. For more information, see Resilience in AWS Backup.

  Note

  One Zone file systems are available to only certain Availability Zones. For a table that lists the Availability Zones in which you can use One Zone file systems, see Supported Availability Zones for One Zone file systems.

The following table compares the file system types, including their availability, durability, and other considerations.

File system type	Designed for	Durability (designed for)	Availability	Availability Zones	Other considerations
Regional	Data requiring the highest durability and availability.	99.999999999% (11 9s)	99.99%	>=3	None
One Zone	Data that doesn't require the highest durability and availability.	99.999999999% (11 9s)	99.99%	1	Not resilient to the loss of the Availability Zone

EFS storage classes

Amazon EFS offers different storage classes that are designed for the most effective storage depending on use cases.

• EFS Standard – The EFS Standard storage class uses solid state drive (SSD) storage to deliver the lowest levels of latency for frequently accessed files. New file system data is first written to the EFS Standard storage class and then can be tiered to the EFS Infrequent Access and EFS Archive storage classes by using lifecycle management.

• EFS Infrequent Access (IA) – A cost-optimized storage class for data that is accessed only a few times each quarter.

• EFS Archive – A cost-optimized storage class for data that is accessed a few times each year or less.

  The EFS Archive storage class is supported on EFS file systems with Elastic throughput. You cannot update your file system’s throughput to Bursting or Provisioned once the file system has data in the Archive storage class.

Optimizing storage costs

The IA and Archive storage classes are cost-optimized for files that don’t require the latency performance of the Standard storage. First byte latency when reading from either of the infrequently accessed storage classes is higher than that for the Standard storage class.

Using lifecycle management, you can optimize storage costs by automatically tiering data between storage classes based on your workload's access patterns. You can move files from the IA or Archive storage classes to the Standard storage class by setting the Transition into Standard lifecycle policy on your file system. This setting transitions files from IA or Archive back to Standard upon access. If you want your files to remain in the frequently accessed Standard storage class, turn off lifecycle management on the file system. For more information, see Managing file system storage.

Comparing storage classes

The following table compares the storage classes. For more details about the performance of each storage class, see Amazon EFS performance.

Storage class	Designed for	First byte read latency	Durability (designed for)1	Availability SLA	Availability zones	Minimum billing charge per file2	Minimum storage duration
EFS Standard	Active data requiring fast sub-millisecond latency performance	Sub-millisecond	99.999999999% (11 9's)	99.99% (Regional) 99.9% (One Zone)	=>3 (Regional) 1 (One Zone)	Not applicable	Not applicable
EFS Infrequent Access	Inactive data that is accessed only a few times each quarter.	Tens of milliseconds				128 KiB	Not applicable
EFS Archive	Inactive data that is accessed a few times each year or less	Tens of milliseconds		99.9% (Regional)	=>3 (Regional)	128 KiB	90 days

Note

¹Because One Zone file systems store data in a single AWS Availability Zone, data that is stored in these types of file systems might be lost in the event of a disaster or other fault that affects all copies of the data within the Availability Zone, or in the event of Availability Zone destruction.

²Lifecycle policies updated on or after 12 PM PT, November 26, 2023 will tier files of < 128 KiB to the IA class. For more information about how Amazon EFS meters and bills for individual files and metadata, see How Amazon EFS reports file system and object sizes.

Storage class pricing

You are billed for the amount of data in each storage class. You are also billed data access charges when files in IA or Archive storage are read, or for data that transitions between storage classes using lifecycle management. The AWS bill displays the capacity for each storage class and the metered access against the file system's storage class. To learn more, see Amazon EFS Pricing.

Additionally, Infrequent Access (IA) and Archive storage classes have a minimum billing charge per file of 128 KiB. Support for files smaller than 128 KiB is only available for lifecycle policies updated on or after 12:00 PM PT, November 26, 2023. For more information on how Amazon EFS meters and bills for individual files and metadata, see How Amazon EFS reports file system and object sizes.

Additional pricing applies for file systems that use Provisioned or Bursting throughput.

• For file systems using Provisioned throughput, you are billed for the throughput provisioned above what you are provided based on the amount of data that is in the EFS Standard storage class.

• For file systems using Bursting throughput, the allowed throughput is determined based on the amount of the data stored in the EFS Standard storage class only.

For more information about EFS throughput modes, see Throughput modes.

Note

You don't incur data access charges when using AWS Backup to back up lifecycle management-enabled EFS file systems. To learn more about AWS Backup with Amazon EFS, see Backing up EFS file systems.