Home > Storage > PowerStore > Data Protection > Dell PowerStore: Metro Volume > Terminology
The following table provides definitions for some of the terms that are used in this document.
Term | Definition |
Appliance | Solution containing a base enclosure and attached expansion enclosures. The size of an appliance could be only the base enclosure or the base enclosure plus expansion enclosures. |
Asynchronous Logical Unit Access (ALUA) | PowerStore uses implicit ALUA which allows PowerStore to provide a recommended active optimized path to a storage resource for the hosts. |
Asynchronous replication | Replication method that allows replicating data over long distances and maintaining a replica at a destination site. Updates to the destination image can be issued manually, or automatically based on a customizable RPO. |
Bandwidth | Amount of data, represented in MB/s, which can be transferred in a given period. |
Common base | Pair of snapshots that are taken on a replication source and destination storage resource that have the same point-in-time image. |
Destination storage resource | Storage resource that is used for disaster recovery in a replication session. This term is also known as a target image. |
Fibre Channel (FC) protocol | Protocol used to perform IP and SCSI commands over a Fibre Channel network. |
File system | Storage resource that can be accessed through file-sharing protocols such as SMB or NFS. |
Internal snapshot (replication snapshot) | The system creates unified snapshots and is part of an asynchronous replication session. These snapshots are only visible in the PowerStore CLI or PowerStore REST API, and manual modification is not possible. Each asynchronous replication session uses up to two internal snapshots that are taken on the source and destination storage resources. Each session also takes up one read/write snapshot on destination storage system. The last successful internal read-only (RO) snapshots for source and destination storage resources and are used as a common base. |
iSCSI | Provides a mechanism for accessing block-level data storage over network connections. |
Metro Volume | Synchronous replicated PowerStore block volume or volume group that provides active-active access for the connected hosts. |
Network-attached storage (NAS) server | File-level storage server used to host file systems. A NAS server is required to create file systems that use SMB or NFS shares. |
Network File System (NFS) | An access protocol that allows data access from Linux or UNIX hosts on a network. |
PowerStore base enclosure | Enclosure containing both nodes (node A and node B) and 25 NVMe drive slots |
PowerStore CLI | Tool that can be installed on an operating system to manage a PowerStore system. |
PowerStore cluster | A group of one or more appliances. Up to four PowerStore appliances can be clustered by adding appliances as required. |
PowerStore Command Line Interface (PSTCLI) | Tool which can be installed on an operating system to manage a PowerStore system. It allows a user to perform tasks on the storage system by typing commands instead of using the graphic user interface. |
PowerStore expansion enclosure | Enclosure that can be attached to a base enclosure to provide additional storage. |
PowerStore Manager | Web-based management interface for creating storage resources and configuring and scheduling protection of stored data on PowerStore. PowerStore Manager can be used for all management of PowerStore native replication. |
PowerStore node | Storage controller that provides the processing resources for performing storage operations and servicing I/O between storage and hosts. Each PowerStore appliance contains two nodes. |
PowerStore Representational State Transfer (REST) API | Set of resources (objects), operations, and attributes that provide interactive, scripted, and programmatic management control of the PowerStore cluster. |
PowerStore Q model | Container-based storage system that is running on purpose-built hardware. This storage system supports unified (block and file) workloads, or block-optimized workloads. The PowerStore Q model supports Quad-Level Cell (QLC) NVMe SSDs for data storage. |
PowerStore T model | Container-based storage system that is running on purpose-built hardware. This storage system supports unified (block and file) workloads, or block-optimized workloads. The PowerStore T model supports Triple-Level Cell (TLC) NVMe SSDs for data storage. |
RecoverPoint for Virtual Machines | Protects virtual machines (VMs) in a VMware environment with VM-level granularity and provides local or remote replication for any point-in-time recovery. This feature is integrated with VMware vCenter and has integrated orchestration and automation capabilities. |
Recovery point objective (RPO) | Acceptable amount of data, which is measured in units of time, that may be lost due to a failure. For example, if a storage resource has a one-hour RPO, data that is written to the storage resource within the last hour may be lost when the replication session is failed over to the destination storage resource. |
Recovery time objective (RTO) | Duration of time in which a business process must be restored after a disaster. For example, an RTO of one hour requires restoring data access within one hour after a disaster occurs. |
Remote systems | Relationship that is configured between two PowerStore systems to establish a replication session. |
Replication session | Relationship that is configured between two storage resources of the same type on different systems, and automatically synchronizes data from one resource to another. |
Snapshot | Also called a unified snapshot, a snapshot is a point-in-time view of a storage resource. When a snapshot is taken, it creates an exact copy of the source storage resource and shares all blocks of data with it. As data changes on the source, new blocks are allocated and written to. Unified snapshot technology can be used to take a snapshot of a block or file storage resource. |
Storage resource | Top-level object that a user can provision, which is associated with a specific quantity of storage. All host access and data-protection activities are performed at this level. In this document, storage resources refer to resources that support replication such as volumes, volume groups, and thin clones. |
Synchronous replication | Replication method in which the host initiates a write to the system at the local site. The data must be successfully stored in both the local and destination systems before an acknowledgment is sent back to the host. Guarantees zero-data-loss RPO while source and destination are synchronized. |
Thin clone | Read-write copy of a thin block storage resource (volume, volume group, or VMware vSphere VMFS datastore) that shares blocks with the parent resource. |
Unisphere Manager for RecoverPoint | Web-based interface for managing RecoverPoint replication. It serves as a single pane of glass for replicating storage resources of multiple storage systems that are configured to use RecoverPoint. Consistency groups are created, replicated, and recovered through this interface. |
User snapshot | Snapshot that the user creates manually, or a protection policy creates with an associated snapshot rule. This snapshot type is different than an internal snapshot, which the system with asynchronous replication takes automatically. |
Virtual Volumes (vVols) | VMware storage framework which allows VM data to be stored on individual Virtual Volumes. This ability allows data services to be applied at a VM-granularity level while using Storage Policy Based Management (SPBM). |
Volume | Block-based storage resource that a user provisions. It represents a SCSI logical unit. |
Volume group | Storage instance that contains one or more volumes within a storage system. Volume groups can be configured with write-order consistency and help organize the storage that is allocated for particular hosts. |
vStorage API for Array Integration (VAAI) | VMware API that allows storage-related tasks to be offloaded to the storage system. |
vSphere API for Storage Awareness (VASA) | VMware API that provides additional insight about the storage capabilities in vSphere. |
vSphere Metro Storage Cluster (vMSC) | VMware based solution that combines replication with array-based clustering. |
Witness | An independent service deployed at a third site which adds additional resiliency to Metro Volume storage availability scenarios. |