2.1. Storage architecture overview¶
The fundamental component of Acronis Cyber Infrastructure is a storage cluster: a group of physical servers interconnected by network. Each server in a cluster is assigned one or more roles and typically runs services that correspond to the following roles:
Storage role: chunk service (CS)
Metadata role: metadata service (MDS)
Supplementary roles:
SSD cache
系统
Any server in the cluster can be assigned a combination of storage, metadata, and supplementary roles.
每个簇还要求基于 Web 的管理面板安装在其中一个（仅一个）节点上。该面板使管理员能够管理簇。
2.1.1. Storage role¶
存储节点运行区块服务、以固定大小区块的形式存储所有数据，以及提供对这些区块的访问。将复制所有数据区块，并且副本保留在不同的存储节点上，以实现数据的高可用性。如果其中一个存储节点失败，则剩余的正常运行的存储节点继续提供故障节点上存储的数据区块。
The storage role can only be assigned to a server with disks of a certain capacity.
2.1.2. Metadata role¶
元数据角色运行元数据服务、存储簇元数据，以及控制如何将用户文件拆分到区块以及区块所在的位置。元数据节点还确保区块有所需的副本量。最后，它们记录在簇中发生的所有重要的事件。
为了提供系统可靠性，Acronis Cyber Infrastructure 使用 Paxos 一致性算法。如果大多数运行元数据服务的节点都运行正常，它可保证容错。
To ensure high availability of metadata in a production environment, metadata services must be run on at least three cluster nodes. In this case, if one metadata service fails, the remaining two will still be controlling the cluster. However, it is recommended to have at least five metadata services to ensure that the cluster can survive simultaneous failure of two nodes and without data loss.
2.1.3. Supplementary roles¶
- SSD 缓存
Boosts chunk read/write performance by creating write caches on selected solid-state drives (SSDs). It is also recommended to use such SSDs for metadata; refer to Metadata role for more information. The use of write journals may more than double the write speed in the cluster.
- 系统
为操作系统保留的每节点一个磁盘，并且不可用于数据存储。