Explanation
➢ Intelligent Storage Systems are feature-rich RAID arrays that provide highly optimized
I/O processing capabilities.
➢ These storage systems are configured with a large amount of memory (called cache) and
multiple I/O paths and use sophisticated algorithms to meet the requirements of
performance-sensitive applications.
➢ An intelligent storage system consists of four key components (Refer Fig 1.21):
Fig 1.21 Components of an Intelligent Storage System
1.14.1 Front End
➢ The front end provides the interface between the storage system and the host.
➢ It consists of two components:
i. Front-End Ports
ii. Front-End Controllers.
✓ Front End
✓ Cache
✓ Back end
✓ Physical disks
Front End
➢ The front end provides the interface between the storage system and the host.
➢ It consists of two components:
i. Front-End Ports
ii. Front-End Controllers.
➢ A front end has redundant controllers for high availability, and each controller contains
multiple front-end ports that enable large numbers of hosts to connect to the intelligent
storage system.
➢ Each front-end controller has processing logic that executes the appropriate transport
protocol, such as Fibre Channel, iSCSI, FICON, or FCoE for storage connections.
➢ Front-end controllers route data to and from cache via the internal data bus.
➢ When the cache receives the write data, the controller sends an acknowledgment message
back to the host.
Cache
➢ Cache is semiconductor memory where data is placed temporarily to reduce the time
required to service I/O requests from the host.
➢ Cache improves storage system performance by isolating hosts from the mechanical
delays associated with rotating disks or hard disk drives (HDD).
➢ Rotating disks are the slowest component of an intelligent storage system. Data access on
rotating disks usually takes several millisecond because of seek time and rotational latency.
➢ Accessing data from cache is fast and typically takes less than a millisecond.
➢ On intelligent arrays, write data is first placed in cache and then written to disk.
Back End
➢ The back end provides an interface between cache and the physical disks.
➢ It consists of two components:
i. Back-end ports
ii. Back-end controllers.
➢ The back end controls data transfers between cache and the physical disks.
➢ From cache, data is sent to the back end and then routed to the destination disk.
➢ Physical disks are connected to ports on the back end.
➢ The back end controller communicates with the disks when performing reads and writes
and also provides additional, but limited, temporary data storage.
➢ The algorithms implemented on back-end controllers provide error detection and
correction, and also RAID functionality.
➢ For high data protection and high availability, storage systems are configured with dual
controllers with multiple ports.
Physical Disk
➢ A physical disk stores data persistently.
➢ Physical disks are connected to the back-end storage controller and provide persistent data
storage.
➢ Modern intelligent storage systems provide support to a variety of disk drives with
different speeds and types, such as FC, SATA, SAS, and flash drives.
➢ They also support the use of a mix of flash, FC, or SATA within the same array.