Cloud Storage Gateway (CSG) file gateways support Standard, Infrequent Access (IA), and Archive storage classes of OSS buckets, each with different behaviors for read and write operations.
Supported storage classes
CSG file gateways support the following OSS bucket storage classes:
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Standard
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Infrequent Access (IA)
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Archive
Read behavior for archived files
When a read request targets an archived file, the gateway automatically starts a restore operation. The behavior differs by share protocol:
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NFS shares: The request does not return an error but experiences I/O latency during restoration.
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SMB shares: A temporary error may occur. The read operation succeeds after the file is restored.
Write behavior and archive limitations
When a client writes a file to a file gateway, the gateway records at least two actions: writing the file and setting the file modification time. The gateway merges these actions where possible but may still send multiple operations on the object to the bucket. Setting the modification time triggers a CopyObject operation to store the timestamp as object metadata. For Archive or Cold Archive objects, this operation requires restoration, which increases upload time and may cause upload failures if cache data cannot be uploaded in time.
Do not connect a gateway directly to an Archive or Cold Archive bucket. Instead, use a Standard or IA bucket and configure a lifecycle rule to transition objects to Archive or Cold Archive after they are written. This approach eliminates unnecessary restoration operations and optimizes both storage costs and efficiency.