27.2. libStorageMgmt Terminology
Different array vendors and storage standards use different terminology to refer to similar functionality. This library uses the following terminology.
- Storage array
- Any storage system that provides block access (FC, FCoE, iSCSI) or file access through Network Attached Storage (NAS).
- Storage Area Network (SAN) Storage Arrays can expose a volume to the Host Bus Adapter (HBA) over different transports, such as FC, iSCSI, or FCoE. The host OS treats it as block devices. One volume can be exposed to many disks if
multipathis enabled).This is also known as the Logical Unit Number (LUN), StorageVolume with SNIA terminology, or virtual disk.
- A group of storage spaces. File systems or volumes can be created from a pool. Pools can be created from disks, volumes, and other pools. A pool may also hold RAID settings or thin provisioning settings.This is also known as a StoragePool with SNIA Terminology.
- A point in time, read only, space efficient copy of data.This is also known as a read only snapshot.
- A point in time, read writeable, space efficient copy of data.This is also known as a read writeable snapshot.
- A full bitwise copy of the data. It occupies the full space.
- A continuously updated copy (synchronous and asynchronous).
- Access group
- Collections of iSCSI, FC, and FCoE initiators which are granted access to one or more storage volumes. This ensures that only storage volumes are accessible by the specified initiators.This is also known as an initiator group.
- Access Grant
- Exposing a volume to a specified access group or initiator. The
libStorageMgmtlibrary currently does not support LUN mapping with the ability to choose a specific logical unit number. The
libStorageMgmtlibrary allows the storage array to select the next available LUN for assignment. If configuring a boot from SAN or masking more than 256 volumes be sure to read the OS, Storage Array, or HBA documents.Access grant is also known as LUN Masking.
- Represents a storage array or a direct attached storage RAID.
- File system
- A Network Attached Storage (NAS) storage array can expose a file system to host an OS through an IP network, using either NFS or CIFS protocol. The host OS treats it as a mount point or a folder containing files depending on the client operating system.
- The physical disk holding the data. This is normally used when creating a pool with RAID settings.This is also known as a DiskDrive using SNIA Terminology.
- In Fibre Channel (FC) or Fibre Channel over Ethernet (FCoE), the initiator is the World Wide Port Name (WWPN) or World Wide Node Name (WWNN). In iSCSI, the initiator is the iSCSI Qualified Name (IQN). In NFS or CIFS, the initiator is the host name or the IP address of the host.
- Child dependency
- Some arrays have an implicit relationship between the origin (parent volume or file system) and the child (such as a snapshot or a clone). For example, it is impossible to delete the parent if it has one or more depend children. The API provides methods to determine if any such relationship exists and a method to remove the dependency by replicating the required blocks.