Network Storage protocols and related technical basics

SCSI

SCSI is short for the small computer system interface (Small Computer System Interface). It was first proposed in 1979 as an interface technology developed for minicomputers and has been widely used in minicomputers, high-end servers and normal PCs.

SCSI can be divided into SCSI-1, SCSI-2, SCSI-3, the latest SCSI-3, is also currently the most widely used SCSI version.

1. SCSI-1: proposed in 1979, support synchronous and asynchronous SCSI peripheral devices; Support 7 8-bit peripheral devices, the maximum data transmission speed is 5 Mb/s.

2. SCSI-2: proposed in 1992, also known as fast SCSI, data transmission rate increased to 20 Mb/s.

3. SCSI-3: proposed in 1995, ultra SCSI (fast-20 ). Ultra 2 SCSI (fast-40) appeared in 1997, with a maximum transmission rate of 80 Mb/s. In September 1998, ultra 3 SCSI (utra 160 SCSI) was officially released with a maximum data transmission rate of 160 Mb/s. The maximum data transmission rate of Ultra 320 SCSI has reached 320 Mb/s.

FC (Fiber Channel)

FC Fiber Channel: used for data transmission between computer devices. The transmission rate reaches 2 GB (4 GB in the future ). Fiber Channel is used to connect the server to share the storage device, and the internal connection between the storage controller and the drive.

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Basic protocol architecture:

FC-4 upper layer protocol: SCSI, hippi, sbccs, 802.2, ATM, Vi, IP

The FC-3 common service

FC-2 (framing protocol/Flow Control)

FC-1 encode/decode

FC-0 media: optical or copper, 100 mb/sec to 1.062 GB/sec

Protocol layer description:

FC-0: physical layer, custom different media, transmission distance, signal mechanism standard, also defines the optical fiber and copper Interface

And Cable indicators

FC-1: defining encoding and decoding standards

FC-2: defines frame, stream control, and service quality

FC-3: defines common services such as data encryption and Compression

FC-4: Protocol ing layer, defines the interface between the Fiber Channel and the upper application, the upper application such as: Serial SCSI negotiation, HbA Driver provides FC-4 interface function, FC-4 supports multiple protocols such as: FCP-SCSI, FC-IP, FC-VI

Protocol Introduction:

FCP-SCSI:

FCP-SCSI: a protocol that converts a SCSI parallel interface into a serial interface and is used for data transmission between the storage system and the server. The new ANSI T10 standard supports direct data movement between storage systems on the San through data migration applications. The FCP-SCSI provides a transmission rate of 200 Mb/s (full-duplex exclusive bandwidth), each connection up to 10 km, up to 16000000 nodes. The FCP-SCSI replaces block transfer with frame transfer. Frame transmission transmits short and small transaction data in the transmission mode of large data streams.

ISCSI

ISCSI is a standard for data block transmission over TCP/IP. It was initiated by Cisco and IBM and has received strong support from various storage vendors. Iscsi can run the SCSI protocol on an IP network so that it can perform fast data access and backup operations on high-speed Gigabit Ethernet.

The iSCSI standard was approved by IETF (Internet Engineering Task Force) in February 11, 2003. Iscsi inherits two traditional technologies: SCSI and TCP/IP. This laid a solid foundation for the development of iSCSI.

The iscsi-based storage system can implement the SAN storage function without a small investment, and even directly use the existing TCP/IP network. Compared with the previous network storage technology, it solves problems such as openness, capacity, transmission speed, compatibility, and security. Its superior performance has attracted more attention and favor.

ISCSIData Packet structure:

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Workflow:

The iSCSI system sends a SCSI command by the SCSI adapter.

Commands are encapsulated in TCP/IP packets and sent to the Ethernet.

The receiver extracts SCSI commands from TCP/IP packets and performs related operations.

Encapsulate the returned SCSI commands and data in the TCP/IP package and send them back to the sender.

The system extracts data or commands and sends them back to the SCSI subsystem.

Security description:

The iSCSI protocol provides QoS and security features.

You can restrict the initiator to send a login request only to the target in the target list, and then confirm the request by the target and return the response.

Communication is allowed;

Encrypted data packets are transmitted through IPSec, including data integrity, certainty, and confidentiality detection;

 

Advantages of iSCSI

(1) widely distributed Ethernet networks provide the foundation for iSCSI deployment.

(2) The popularization of gigabit/10G Ethernet provides higher bandwidth for iSCSI.

(3) The popularization of Ethernet Knowledge provides a large number of management talents for storage technologies based on iSCSI technology.

(4) based on the TCP/IP network, it completely solves the difficulties of Data Replication and Disaster Recover.

(5) thanks to the price advantages of Ethernet devices and the openness and convenient management of TCP/IP networks, the cost of device expansion and application adjustment is low.

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Network Storage protocols and related technical basics