The physical disks in an ACOS cluster contain the following types of partitions:
Operating system partition
The operating system partition is used to deploy the ACOS system. It contains the files and components required by the operating system to ensure proper system operation.
Metadata partition
The metadata partition carries critical ZooKeeper data and metadata for the cluster. This data stores information about cluster configuration, status, and metadata, ensuring the cluster runs properly.
Journal partition
The journal partition is used to record write operation logs on the physical disk. When a write operation is performed on storage, the operation log will be written to the journal partition, enabling data recovery and verification in case of exceptions.
Cache partition
The cache partition is used to improve system performance. On heterogeneous storage media, when space is available or a read operation hits the cache, I/O operations will prioritize the cache partition, accelerating data access and improving responsiveness. On a single storage medium, no read cache exists. In tiered storage mode, the cache partition also persists performance layer data.
Data partition
The data partition is used for persistent storage. In tiered mode, compared with the cache partition, the data partition has lower performance but larger capacity, and it persists capacity layer data. In non-tiered mode, the data partition offers higher performance, and no additional cache partition is required to improve read performance.
