The fundamental building blocks of an APEX Block Storage solution are:
MDM – Meta Data Manager – The brains of the storage layer
- Oversees storage cluster configuration, monitoring, rebalancing, and rebuilding.
- A highly available, independent cluster installed on three or five different nodes.
- May reside alongside SDCs and/or SDSs or on separate instances.
- Located outside the data path.
SDR – Storage Data Replicator
- Handles replication activities between Dell APEX Block Storage systems.
- Located alongside the SDS on the same node.
- Highly available. If failure occurs, the MDM instructs the SDC to send data to alternative SDRs.
- The Source journals incoming writes and ships them to the target.
- The Target receives the journal and applies it to the target volumes.
SDC – Storage Data Client (Consumer of storage)
- Provides front-end volume access to applications and file systems
- Installed on instances that are consuming storage
- Maintains peer-to-peer connections to every SDS managing a pool of storage
- Understands how to make read and write requests to different parts of the system
SDS – Storage Data Server (Supplier of storage)
- Abstracts local storage, maintains storage pools, and presents volumes to the SDCs.
- Installed on instances that contribute local disks to the storage cluster.
- A protection domain is a collection of SDS instances.
- Manages the data that is spread evenly across all the contributing nodes in the cluster. This provides the opportunity for massively parallel processing.
APEX Block Storage for AWS management instances (MDM and MDM tiebreaker), Secure Connect Gateway (SCG), APEX Block Storage Manager Platform, and proxy server instances use AWS EBS gp3 volumes exclusively.