SCM是块空间管理的领导节点 它的主要责任是 创建和管理containers containers是OZone的主要复制单元

Storage container manager provides multiple critical functions for the Ozone cluster. SCM acts as the cluster manager, Certificate authority, Block manager and the Replica manager.

SCM为OZone集群提供了多种关键功能 SCM充当集群管理者、证书管理、块管理和副本管理等。

SCM is in charge of creating an Ozone cluster. When an SCM is booted up via init command, SCM creates the cluster identity and root certificates needed for the SCM certificate authority. SCM manages the life cycle of a data node in the cluster.

SCM 负责创建一个 Ozone 集群 当通过 init 命令启动 SCM 时 SCM 会创建集群标识以及用于担任 CA 的根证书 SCM 负责集群中数据节点生命周期管理。

------①SCM is the block manager. SCM allocates blocks and assigns them to data nodes. Clients read and write these blocks directly.

SCM 管理 Ozone 中的块 它将块分配给数据节点 用户直接读写这些块。

------②SCM keeps track of all the block replicas. If there is a loss of data node or a disk, SCM detects it and instructs data nodes make copies of the missing blocks to ensure high availability.

SCM 会跟踪所有块副本的状态 如果检测到数据节点宕机或磁盘异常 SCM 命令其它节点生成丢失块的新副本 以此保证高可用。

------③ SCM’s Ceritificate authority is in charge of issuing identity certificates for each and every service in the cluster. This certificate infrastructure makes it easy to enable mTLS at network layer and the block token infrastructure depends on this certificate infrastructure.

SCM 的 CA 负责向集群中的每个服务颁发身份证书 证书设施方便了网络层 mTLS 协议的启用 也为块 token 机制提供了支持。

跟OM一节介绍的规则一样 本节介绍SCM提供的网络服务和存储的持久化数据

①Pipelines: List/Delete/Activate/Deactivate
---------pipelines are set of datanodes to form replication groups
---------Raft groups are planned by SCM

②Containers: Create / List / Delete containers
③Admin related requests
④Safemode status/modification
⑤Replication manager start / stop
⑥CA authority service
⑦Required by other sever components
⑧Datanode HeartBeat protocol
-------------From Datanode to SCM (30 sec by default)
-------------Datanodes report the status of containers, node…
-------------SCM can add commands to the response

The following data is persisted in Storage Container Manager side in a specific RocksDB directory

①Pipelines
-------Replication group of servers. Maintained to find a group for new container/block allocations.
②Containers
------Containers are the replication units. Data is required to act in case of data under/over replicated.
③Deleted blocks
------Block data is deleted in the background. Need a list to follow the progress.
④Valid cert, Revoked certs
⑤Used by the internal Certificate Authority to authorize other Ozone services