Commvault® software is deployed in a cell-like structure called a CommCell® environment. One or more cells can be deployed to manage small to enterprise global environments. Consider the following advantages and disadvantages when planning for a single cell or multi-cell structure.
Single CommCell environment
Provides central management.
Allows data to easily be restored across all sites.
If the central site hosting the CommServe server goes offline, all data management activities will be disrupted.
Provides full autonomy and resiliency.
Allows each IT group to independently manage their environment.
Cross-site restore operations are more complicated if each site is its own CommCell structure.
The central component of a CommCell environment is the CommServe® server which coordinates, manages and monitors all CommCell activity. Production data is protected by installing agents which directly communicate with the operating system or application being protected. Any production server with an agent installed is referred to as a client. Data is protected by transferring data through MediaAgents to storage, which can be disk, cloud or tape.
Physical architecture high level diagram
The CommServe® Server is the central management system within a CommCell® environment. All activity is coordinated and managed by the CommServe server. The CommServe server runs on a Windows platform and maintains a Microsoft SQL metadata database. This database contains all critical configuration information. It is important to note that Commvault® software does not use a centralized catalog system like most other backup products. This means the metadata database on the CommServe server will be considerably smaller than databases that contain catalog data. Due to the small size of the database, an automated backup of the database is executed by default every morning at 10:00 AM.
CommServe server high level diagram
A MediaAgent moves data from production systems to protected storage during data protection jobs and moves data back to production systems during recovery operations. It is a software module that can be installed on most operating systems. All tasks are coordinated by the CommServe® server. MediaAgents are also used during auxiliary copy jobs when data is copied from a source storage to a destination storage device such as off-site Disaster Recovery (DR) copies.
There is a basic rule that all data must travel through a MediaAgent to reach its destination. One exception to this rule is when conducting Network Data Management Protocol (NDMP) dumps directly to tape media. In this case the MediaAgent is used to execute the NDMP dump and no data will travel through the MediaAgent. This rule is important to note as it will affect MediaAgent placement.
Commvault® software uses a distributed indexing structure where index data is kept on MediaAgents and is also automatically copied to storage. Using a distributed indexing structure allows Commvault software to scale significantly more than legacy backup products and keeps indexes local to where data is being protected.
When data is protected, indexes are automatically generated and written to the MediaAgent's Index Directory location. At the conclusion of the job, indexes or index logs are copied to the store location where the job resides. During restore operations, the index database within the index directory is accessed. If the index database is not available, it will automatically be restored from the storage media. Commvault uses two primary indexing methods: the traditional V1 indexing and the new V2 indexing method.
Disk A disk device is a logical container which is used to define one or more paths to storage called backup locations, or mount paths. These paths are defined explicitly to the location of the storage and can be defined as a drive letter or a UNC path. Within each mount path, writers are allocated, which defines the total number of concurrent streams for the mount path.
Tape A tape unit or removable media library is a storage device where media can be added, removed and moved between multiple units. The term removable media is used to specify various types of removable media supported by Commvault® software including tape and USB disk drives, which can be moved between MediaAgents for data protection and recovery operations.
Cloud A cloud storage device is cost-effective storage that reduces the need to maintain hardware resources, such as tape or disk storage devices. It also provides the ability to easily increase your storage capacity when required. Cloud storage provides centralized data access, better failover capabilities and reduces the day-to-day storage administration tasks.