Managing file system storage
To manage your file systems so that they are stored cost effectively throughout their lifecycle, use lifecycle management automatically transitions data between storage classes according to the lifecycle configuration defined for the file system. The lifecycle configuration is a set of lifecycle policies that define when to transition the file system's data to another storage class.
Lifecycle policies
Lifecycle policies instruct lifecycle management when to transition files into and out of the EFS Infrequent Access (IA) and EFS Archive storage classes. Transition time is based on when the files were last accessed in the Standard storage class. Lifecycle policies apply to the entire EFS file system.
The EFS lifecycle policies are:
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Transition into IA – Instructs lifecycle management when to move files into the Infrequent Access storage, which is cost-optimized for data that is accessed only a few times each quarter. By default, files that are not accessed in Standard storage for 30 days are transitioned into IA.
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Transition into Archive – Instructs lifecycle management when to move files into the Archive storage class, which is cost-optimized for data that is accessed only a few times each year or less. By default, files that are not accessed in Standard storage for 90 days are transitioned into Archive.
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Transition into Standard – Instructs lifecycle management whether to transition files out of IA or Archive and back into Standard storage, which provides sub-millisecond read latencies for frequently-accessed data. By default, files are not moved back to Standard storage and they remain in the IA or Archive storage class. For performance-sensitive use cases that demand the fastest latency performance (such as applications that work with a large volume of small files), choose to transition files into Standard storage On first access.
For more information about configuring the lifecycle policies for a file system, see Managing lifecycle policies for a file system.
To determine last accessed time in the Standard storage class, an internal timer tracks when a file was last accessed (not the POSIX file system attributes that are publicly viewable). Whenever a file in Standard is accessed, the lifecycle management timer is reset. After lifecycle management moves a file into the IA or Archive storage classes, the file remains there indefinitely unless the Transition into Standard policy is set, which instructs lifecycle management to move files back to Standard when accessed.
Metadata operations, such as listing the contents of a directory, don't count as file access. During the process of transitioning a file's content to the IA or Archive storage classes, the file is stored in the Standard storage class and is billed at that storage rate.
File system operations for lifecycle management
File system operations for lifecycle management have a lower priority than operations for EFS file system workloads. The time required to transition files into or out of IA and Archive storage varies depending on the file size and file system workload.
File metadata, including file names, ownership information, and file system directory structure, is always stored in Standard to help ensure consistent metadata performance. All write operations to files in the file system's IA or Archive storage classes are first written to Standard storage classes, and are then eligible to be transitioned to the applicable storage class after 24 hours.
