2. storage networking and virtualization technology
Chapter 5 describes the direct-attached storage and SCSI
direct-attached storage (DAS) is a memory directly connected to the server architecture.
Built DAS architecture: a storage device through a serial / parallel bus connection to the host, it can support high-speed connections over short distances. Device occupancy space inside the chassis, making it difficult to maintain.
External DAS: a server connected directly to an external storage device. In most cases, SCSI or FC protocol for communication between the host and the storage device. Contrast built DAS, DAS overcome the external device and distance limitations and other issues, and provides centralized management of storage devices.
DAS low cost, simple configuration and easy deployment and fast.
Difficult to expand, the device only limited port, limiting the number of storage devices can be directly connected to the host. Unable to optimize resource use, because it's limited ability to share front-end ports.
DAS issue and there is no memory interconnect network latency problems, there is potential for optimization.
Magnetic disk drive interface
IDE / ATA, ATA, ATA- 2, Fast ATA, ATA-3, Ultra ATA, Ultra DMA and the like. The latest UDMA support throughput of 133MB / s of.
IDE / AT low prices, currently being phased out.
SATA is the IDE / ATA specification of the serial version. Goal is to replace parallel ATA technology. Point to point transmission, the data transfer rate of up to 150 ~ 600MB / s.
SATA bus line will be used for each storage device directly to the host.
SATA hot-pluggable devices, only a single device connected to the port.
Parallel SCSI (referred to as SCSI), typically used to connect the host to the hard disk and tape. It may also be used to connect communications between various types of equipment, storage devices and the host SCSI command set.
Serial attached SCSI disks: Serial Attached SCSI (SAS) satisfies a scalable, high-performance, high reliability and manageability requirements. SCSI command using SAS and SATA compatible with pins. Supports data transfer rate of 3Gbps. It supports dual-port, full-duplex, device addressing. May be connected by a plurality of spreader devices.
Parallel SCSI: FC disk Gigabit network storage. Access to reach the rate of 8Gbps.
Chapter 6 Storage Area Network
Fiber Channel
FC fabric, fiber channel is a high-speed network, fiber optic cables (SAN front stage is connected) and a serial copper (connected to the rear end)
SAN consists of three basic components: a server, storage and network infrastructure equipment. Broken down: node port, cables, interconnects, and SAN storage array management software
Node port
device such as a host computer, and library memories are referred to as nodes. Each port is full-duplex transmission mode with a transmission link and a reception link.
Wiring
general wiring fiber, copper cable is connected to the rear end a short distance.
Interconnect device
switch from one data port transmitting data directly to another port node is not shared bandwidth, but by dedicated communication path.
Arbitrated Loop Fiber Channel
FC-AL, the other devices and each device must contend for the channel with the I / O operation.
FC-AL bandwidth sharing in the ring. Only one device at a time for I / O operations.
FC-SW also referred to fabric connection. All nodes can communicate with each other. FC-SW using the switch, the switch ports, forwards data traffic from one sender node directly to another destination node.
N-port: node port.
NL Port: port nodes on the ring.
Port E: expansion port for connection between the two FC switches.
Port F: a port for connecting the N-port switch, but not for the FC-AL.
FL Port: for FC-AL and FC-SW in.
Fiber Channel Protocol (FCP) has several advantages:
• to maintain a high bandwidth over longer distances.
• Support for a large number of addressable devices on the network.
Transmission channel, providing rates up to 8.5Gbps.
Chapter 7 Network Attached Storage
File Transfer Protocol (FTP) using TCP as the transport protocol to communicate with one another. SSH-based FTP to the original FTP protocol to increase security.
End NAS: external memory dedicated
gateway may be extended up NAS formula, since NAS head and the storage array can be extended to upgrade.
Typical small randomness NAS workload data I / O, is generally recommended to separate NAS and SAN disks used.
Jump large number of network packets will increase delays. Authentication requests will increase the delay.
Virtual LAN (VLAN) switching network is divided logically.
MTU: decided not fragmented transmission maximum packet size. Ethernet card default MTU setting is 1500 bytes.
jumbo frames: for sending and receiving Ethernet MTU larger than 1500 bytes frames. The actual deployment jumbo frames MTU is 9000 bytes. Improves the efficiency, heavy traffic in the network, the more efficient the server to send and receive large frames.
IP SAN Chapter 8
iSCSI and FCIP are two main existing transport protocol IP-based network.
SCSI data is sent or received iSCSI protocol to the host encapsulates IP packets making, and then transmitted by the Ethernet card or iSCSI HBA device.
Due to the low cost and easy to implement, iSCSI has been widely used in the connection between the servers and storage devices.
iSCSI is an IP-based protocol, the connection between the IP establishment and management of the storage device, and the host bridge device. Block-level data transfer using the SCSI protocol encapsulated SCSI commands and data, then use the TCP / IP packet is transmitted.
Supports iSCSI host requires a hardware device, such as support for iSCSI initiator or an iSCSI HBA card. TCP / IP network protocol needs to load iSCSI initiator or other translation modules for converting SCSI commands and TCP / IP protocol stack.
iSCSI HBA can assume the function of the entire iSCSI and TCP / IP protocol stack function alone.
iSCSI discovery: The initiator / host must be able to find the name of the target on the network and the target location prior to establishing a session with the available targets.
By Network Storage Name Service (iSNS) automatic discovery of iSCSI devices on the IP network. The initiator / host and target may be configured to automatically register in the iSNS server. When the host wants access to the target, it can query the iSNS server to obtain a list of available targets.
iSCSI Name: a unique identifier that can be used to identify and manage storage resources.
iSCSI session: between an initiator / host and target established. A session ID identifying a session, includes a host ID (the ISID) and the target (TSID). Each connection iSCSI session has a unique connection ID (CID).
iSCSI PDU: iSCSI protocol data unit and the host uses for communication target. All iSCSI PDU contains one or more header portions, followed or not followed by a plurality of data segments, PDUs are encapsulated into IP packets for transmission.
FCIP uses TCP / IP as a data transmission protocol, expanded and connected by bridges to FCIP gateway existing FC-SAN network, this method can achieve long-range interconnection between the FC-SAN network.
FCIP is a tunneling protocol, the dispersed FC SAN islands transparently through existing IP LAN network for interconnection between the WAN. Using TCP / IP as its underlying protocol. In the FCIP, FC frames into an IP payload. FCIP frame FC does not control (a transmission converter FC ID).
To be continued ......
