1. The basic concept of SAN
1. Concept
SAN (Storage Area Network) is a storage method based on block storage. SAN is a technology that integrates storage devices, connecting devices, and interfaces into a high-speed network. The SAN itself is a storage network, which undertakes data storage tasks. The SAN network and LAN services are isolated from each other, and the storage data stream does not occupy the service bandwidth
. 2. Mode of operation In the
SAN network, all data transmission is in a high-speed, high-bandwidth private network To proceed, SAN storage implements block-level storage access to physical hardware directly, which improves storage performance and upgradeability.
3.
Early development of SAN used Fibre Channel technology, so previous SANs used only Fibre Channel storage. In the area network, after the emergence of the iSCSI protocol, in order to distinguish, the SAN is divided into FC-SAN (using the FC protocol as the transmission protocol and the storage network constructed by the optical cable) and IP-SAN (using the iSCSI protocol as the transmission protocol, using Ethernet Storage network) 4.
The structure of
SAN SAN is actually a kind of dedicated storage network independent of TCP / IP network (independent and data communication network exists, the speed is particularly fast). At present, the general SAN provides a transfer rate of 2GB / s to 4GB / s. SAN generally uses high-end RAID arrays, which makes SAN performance better in storage solutions.
SAN is very expandable because the foundation is a dedicated network. Whether it is to add a certain storage space or increase the number of used storage in a SAN system The servers are very convenient. Through the SAN interface of the tape drive, the SAN system can conveniently and efficiently realize the centralized backup of the data. 5.
The protocol
of the SAN currently uses common SANs: FC-SAN and IP-SAN, of which FC-SAN is through FC. Protocol forwards SCSI protocol, IP-SAN forwards iSCSI protocol through TCP protocol
6. SCSI protocol
The SCSI protocol (Small Computer System Interface) is mainly used to transfer commands, status and data blocks between the host and the storage device. Among various storage technologies, the SCSI protocol is the most important backbone (SCSI protocol data block is the load part in the data packet)
https://blog.51cto.com/11970509/2322308 (with detailed explanation about the SCSI protocol)
| description | SAN |
|---|---|
| Applicable scene | In applications with high I / O requirements based on block operations, such as databases |
| supporting agreement | FC，iSCSI |
| data sharing | Generally exclusive |
| Networking mode | Fiber optic network (FC SAN) or Ethernet (IP SAN) |
| Construction cost | The host needs HBA card, and the fiber optic switch is needed for the network, which costs more |
2. FC SAN
In FC SAN, the protocol used for high-speed data transmission is FC (Fibre Channel, Fibre Channel). The most commonly used cable in this protocol is optical fiber.
1.
FC protocol The first appearance of FC protocol was to improve the transmission bandwidth of hard disk protocol , Focusing on the fast, efficient and reliable transmission of data
FC Fibre Channel has its own protocol layer
2. Prerequisites for
FC SAN- To communicate with the FC host port of the array through the FC protocol, the HBA card host must install FC on the host HBA card (host bus adapter, mainly used to provide input and output processing and physical connection between the server and storage)
The main task of the HBA card is to switch the protocol agreed between the storage device and the host.
The unified use of storage is called HBA card. It is divided into FC-HBA card and iSCSI-HBA card
FC-HBA卡（光纤网卡）：全称为Fibre Channel HBA，它传输的是FC协议，这是专门用于存储网络的中的一种协议，通过光纤线缆与FC交换机（光线存储交换机）相连，然后接入到后端存储矩阵中。它的传输速率最大可以达到2Gb/s--4Gb/s.
备注：大家在实际生产中所说的光纤网卡实际上指的就是FC网卡也就是FC-HBA卡
iSCSI-HBA卡：全称叫做iSCSI HBA卡，它传输的是iSCSI协议，因为iSCSI-HBA卡在传输数据的过程中是将iSCSI协议封装成TCP/IP协议来进行数据传输的，所以iSCSi网卡的接口跟千兆的以太网卡接口相同，都使用双绞线（网线）跟传统的以太网交换机相连，然后接后端接存储矩阵。有时我们也是用iSCSI-HBA卡当做以太网网卡使用让它直接传输以太网的TCP/IP报文。
3.
For partitioning of FC SAN, for security reasons, SAN administrators need to restrict access between specific devices, which can be achieved by using the ZONE method of the fiber switch. In the fiber switch with the Zone set, only the same Zone Devices in order to communicate with each other A device may belong to many different partitions
In a switch, there are two main ways to define Zone
(1) Port zone. In
each Zone, the port number of the device connected to the switch is listed. This requires the administrator of the switch to know exactly which one Which port of the switch to which the fiber is connected
(2) Soft zoning,
also called WWN zoning, in a switch, the devices in the same Zone, through the WWN list to top a Zone zoning
4.
FC network FC SAN network is independent and independent of the communication network. May be composed of multiple switches
A SAN environment is usually configured with two fiber switches, not only to meet the needs of switch redundancy, but also to meet the needs of SAN design
3. IP SAN
1. Features
· TCP / IP protocol as the underlying transmission protocol, using Ethernet as the carrier medium to build the storage area network architecture
· The typical protocol to achieve IP SAN is the iSCSI protocol, which defines the SCSI instruction set transmitted in the IP network Encapsulation method
· IP SAN is a SAN network that uses iSCSI protocol to transmit SCSI data blocks, encapsulates the SCSI blocks into an Ethernet data packet, and then sends them to the network for transmission.
2.
Between IP-SAN typical networking switches Interconnect
· Use a cable to connect two ports on different switches
· Many switches have dedicated upstream ports to interconnect other switches
· Stack of switches
4. Comparison of IP SAN and FC SAN
1. Cost cost
FC SAN Because of the need to purchase a separate fiber switch and fiber HBA card, the cost is relatively high
2. Applicable environment
IP SAN can use the existing IP network, without having to purchase new network equipment, easy to deploy
3.
The difference between
SCSI protocol and iSCSI protocol FC and iSCSI FC SAN encapsulates SCSI data into FC protocol, and then FC protocol transmits
IP IP SAN protocol encapsulates SCSI data into iSCSI protocol, and then transmits through TCP / IP protocol
