Log data is immutable once ingested into Simple Log Service. An append-only storage architecture, multi-replica replication, and cyclic redundancy check (CRC) verification work together to prevent modification, silent corruption, or direct manipulation of stored data.
Simple Log Service uses an append-only storage architecture to ensure data tamper-proofing. The data passes through the following stages:
Clients send log data to the Simple Log Service gateway using the SDK or Logtail.
The gateway performs signature verification and permission checks. Authenticated data is forwarded to the backend worker. Unauthenticated requests are rejected at this boundary.
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The backend worker writes data to the Apsara Distributed File System in an append-only manner for persistent storage. The following properties enforce immutability:
Files for each Logstore are isolated from one another to prevent cross-store interference.
Raw data remains unchanged until the configured time-to-live (TTL) period expires, at which point data is deleted.
The distributed file system is append-only and does not permit modifications to existing file content.
You can enable encryption for a Logstore to store data as ciphertext in the distributed file system. Encryption is independent of the append-only guarantee — both controls apply simultaneously.
Data is stored across multiple replicas and verified by CRC on every write, guarding against silent corruption or direct manipulation.
After confirming data persistence, the worker reports success to the gateway, which then notifies the client. A success response means the data is immutably committed to storage.