Storage Area networking and upcoming trends

Editor's Notes

• #4: By 2016 we almost crossed 3.74 ZB of data. 1 ZB=10^21 So we store our data in these enterprise storage devices
• #5: Front End Communication Communication between compute systems and storage controllers Back end Communication Communication between storage controllers and disks SCSI: Serial communication serial interface Integrated Drive Electronics or IBM Disc Electronics, IDE is more commonly known as ATA or Parallel ATA (PATA)
• #6: difference b/w Block file based storage systems is who is hosting the file systems The file system has two components: user component and storage component. The user component of the file system performs functions such as hierarchy management, naming, and user access control. The storage component maps the files to the physical location on the storage device Good examples of NAS include HDFS(Hadoop distributed file system) and Google File system. In Object level access type of access, the file system’s user component resides on the compute system and the storage component resides on the storage system. Data is accessed over a network in terms of self-contained objects with a unique object identifier.Tersely, Block Storage and File Storage are designed to be consumed by your operating system, Object Storage is designed to be consumed by your application.Another difference between Object Storage and the other storage types is that object metadata lives directly in the object, rather than e.g. in a separate inode.
• #7: A storage area network is a network which enables communication between compute and storage system or between two storage systems. In block access data centers first created "islands" of SCSI disk arrays as direct-attached storage (DAS), each dedicated to an application, often visible as a number of "virtual hard drives" addressed as Logical Unit Numbers (LUNs). Usually LUNS are not shared among Operating systems The whole concept of SAN was probably designed keeping how could one share a hard drive over a network.
• #8: Fiber Channel network topologies consist of the following: Point to Point: enables direct connection between nodes Arbitrated Loop—A network consisting of hub which forwards packets to all ports Switched Fabric—A network consisting of switching elements.
• #9: Small Computer System Interface (SCSI) is a set of standards for physically connecting and transferring data between computers and peripheral devices.  SCSI is the command protocol that works at the application layer of the Open SystemInterconnection (OSI) model. Set of standards defined for physical connection and transferring data between external devices.
• #10: FC operates at very high rates (1, 2, 4, 8, 16, 32, and 128 Gbps) though in practice I have seen only upto 16 gbps used till now Difference between HBA and CNA is that CNA has the ability send traffic through both Ethernet and FC network whereas HBA are limited to FC use only The FC cable connects to devices using either Host based Adapter or Converged Network Adapter. Every HBA has a pre configured WWN(World wide name) Address which is similar to MAC address in Ethernet networks.  Each HBA has a unique World Wide Name (WWN), which is similar to an Ethernet MAC address in that it uses an Organizationally Unique Identifier (OUI) assigned by the IEEE. However, WWNs are longer (8 bytes) unlike MAC(6 bytes)
• #11: FC ProtocolFiber Channel consists of the following layers: FC-0 -- The interface to the physical media FC-1 -- The encoding and decoding of data and out-of-band physical link control information for transmission over the physical media FC-2 -- The transfer of frames, sequences and Exchanges comprising protocol information units. FC-3 -- Common Services required for advanced features such as striping, hunt group and multicast. FC-4 -- Application interfaces that can execute over Fiber Channel such as the Fiber Channel protocol for SCSI (FCP).
• #12: IP SANs can be used to connect SANs over long Distances as IP network has no distance limitation unlike FC Key components for iSCSI communication are:• iSCSI initiators such as an iSCSI HBA• iSCSI targets such as a storage system with an iSCSI port• IP-based network such as a Gigabit Ethernet LANAn iSCSI initiator sends commands and associated data to a target and the targetreturns data and responses to the initiator. iSCSI is the session-layer protocol that initiates a reliable session between devices that recognizeSCSI commands and TCP/IP.
• #13: IP SANs can be used to connect SANs over long Distances as IP network has no distance limitation unlike FC Key components for iSCSI communication are:• iSCSI initiators such as an iSCSI HBA• iSCSI targets such as a storage system with an iSCSI port• IP-based network such as a Gigabit Ethernet LANAn iSCSI initiator sends commands and associated data to a target and the targetreturns data and responses to the initiator. iSCSI is the session-layer protocol that initiates a reliable session between devices that recognizeSCSI commands and TCP/IP.
• #14: The FCoE protocol specification replaces the FC-0 and FC-1 layers of the FC stack with Ethernet.This provides the capability to carry the FC-2 to the FC-4 layer over the Ethernet layer.
• #15: Block-level storage virtualization aggregates block storage devices (LUNs) and enablesprovisioning of virtual storage volumes, independent of the underlying physical storage. Avirtualization layer, which exists at the SAN, abstracts the identity of block-based storage systemsand creates a storage pool by aggregating LUNs from the storage systems. Virtual SAN (also called virtual fabric) is a logical fabric on an FC SAN, which enablescommunication among a group of nodes regardless of their physical location in the fabric. In aVSAN, a group of node ports communicate with each other using a virtual topology defined on thephysical SAN N_Port ID virtualization (NPIV) enables a single N_Port (such as an FC HBA port) tofunction as multiple virtual N_Ports. Each virtual N_Port has a unique WWPN identity inthe FC SAN. This allows a single physical N_Port to obtain multiple FC addresses.Hypervisors leverage NPIV to create virtual N_Ports on the FC HBA and then assign thevirtual N_Ports to virtual machines (VMs). A virtual N_Port acts as a virtual FC HBA port.This enables a VM to directly access LUNs assigned to it (see the figure on the slide).NPIV enables an administrator to restrict access to specific LUNs to specific VMs usingsecurity techniques like zoning and LUN masking; similarly to the assignment of a LUN toa physical compute system.
• #16: Datastores are logical containers that hide specifics of each storage device and provide a uniformmodel for storing virtual machine files. Depending on the type of storage that you use, datastorescan be formatted with VMware vSphere® VMFS, or datastores can be formatted with a file systemnative to a storage device that is shared using the NFS protocol.