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| title | date | weight | summary |
|---|---|---|---|
| Storage Container Manager | 2017-09-14 | 3 | Storage Container Manager or SCM is the core metadata service of Ozone. SCM provides a distributed block layer for Ozone. |
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 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's Ceritificate authority is in charge of issuing identity certificates for each and every service in the cluster. This certificate infrastructre makes it easy to enable mTLS at network layer and also the block token infrastructure depends on this certificate infrastructure. {{}}
{{}} SCM is the block manager. SCM allocates blocks and assigns them to data nodes. Clients read and write these blocks directly. {{}}
{{}} SCM 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 avialablity. {{}}