TWI406545B - Method for access remote logic device with multi-path in linux operation system - Google Patents

Abstract

Method for access remote logic device with multi-path in Linux operation system is disclosed. The method is used for implement access remote devices with multi-paths between initiator and target in a storage area network (SAN). First, a connection is built between initiator and target. Afterward, the initiator sends a request to the target for setting at least one session. And then, the initiator receives allocation informs of the iSCSI Host. The initiator retrieves storage devices of the corresponding iSCSI Host by means of sending a report LUN command. And than, the initiator allocates a device-mapper for generates a redundancy devices inform according to storage devices and its corresponding logic unit number (LUN). And the initiator maps those redundancy storage devices into a mapped device.

Description

Method for multi-path access remote logic device under Linux system

The present invention is a method for accessing a remote logical device, and in particular, a method for multipath access to a remote logical device under a Linux system.

Storage Area Network (SAN) refers to the virtual large-scale connection of multiple distributed storage devices on the Internet through the Internet Small Computer Systems Interface (iSCSI) protocol. The technology of storage devices. The user accesses the data on the remote logical disk through a storage area network (SAN), just like accessing the local hard disk device. Compared with the existing RAID technology, the storage area network established by iSCSI technology has the high-speed transmission characteristics of the Small Computer Interface (SCSI) and the high scalability of the existing storage devices. Therefore, the storage area network has gradually become a popular technology related to information storage. A storage area network, which includes an initiator (initiator) and a target (Target). The so-called initiator can be considered to require access to the provider, and the target can be considered to be the provider of the storage device. The target end generates a plurality of Logic Unit Numbers (LUNs), which correspond to physical storage devices on the network. After the initiator establishes a session with the target, these logical unit numbers are obtained and assigned to the user. The user searches for the logical unit number and accesses the aforementioned physical storage device through the iSCSI command command. In general, only one conversation will be established between the initiator and the target. If multi-path Input/Output is allowed between the initiator and the target, fault-tolerant backup and load balancing can be achieved.

In general, the operating system of the Linux operating system is more stable and stable than the Windows operating system. The use of the Linux operating system by the service server means that the system stability of a higher specification can be achieved. In addition, these service servers can improve system availability and data reliability if they support multi-path reading and writing and avoid data duplication. However, under the Linux operating system, some initiators and targets of the storage area network cannot support multi-path reading and writing at all; in addition, some initiators and targets provide multiple paths for reading and writing, but in the inquiry of different logic. When the unit number is found, the content of the accessed material is found to be the same. In this way, how to enable the storage area network in the Linux system environment to support multi-path access and avoid the emergence of two logical devices with the same content has become an important information topic in the field of storage area networks.

In view of the above Linux system environment, multi-path access to remote logical devices or access to different logical device numbers (LUNs) is obtained, but the same data content is obtained. The object of the present invention is to provide a method for multi-path access to a remote logical device in a Linux system, by finding a connection device accessing the same logical unit number among all connected hosts, and connecting these wired device groups The grouping is a unique mapping device, so that each mapping device is mapped to a different logical unit number to solve the aforementioned problem of accessing the same data content.

In order to access the remote logical device (Logic Device) while supporting the above multipath, and avoiding accessing the Logic Unit Number (LUN), it is found that the same data content is obtained. The method for multi-path access to the remote logical device in the Linux system of the present invention is as follows: First, a communication connection is established between the initiator end and the target end. Then, the initiator requests to establish at least one online conversation with the target. Thereafter, the initiator obtains at least one iSCSI connection host allocated by the target. Then, the originating end obtains a message corresponding to at least one connected device of the SCSI connection host by transmitting a report LUN command. Finally, the initiator configures a device mapper, and the device mapper generates redundant device information according to the obtained wired device and the corresponding logical unit number, and maps the redundant wired devices to a unique mapping device (ie, Map device number, mapped LUN). The so-called redundant connection device refers to multiple connection devices accessing the same logical unit number.

According to a preferred embodiment of the present invention, the communication connection may be a communication connection established by a Transmission Control Protocol (TCP) protocol or a User Datagram Protocol (UDP) protocol. The establishment of the connection dialog includes: first sending an iSCSI login request packet to the target end by the initiator; and then determining, by the target end, whether to allow the initiator to transmit according to the information such as the security authentication and password parameters parsed by the iSCSI login request packet. The access request; finally, the target end returns the iSCSI login response packet to the initiator, and establishes the connection session.

In accordance with a preferred embodiment of the present invention, the information of the iSCSI login response piggyback includes the allowable connection instructions and the connection status. In addition, the aforementioned report LUN command is loaded in the Command Description Block in the SCSI packet.

According to a preferred embodiment of the present invention, traffic occurs when one of the connection sessions occurs When the congestion occurs, the foregoing device mapper performs network offloading means to switch part of the traffic to another mapped device to balance the load; in addition, when the connection session is interrupted, the device mapper switches to transmit the data packet to another mapping device. .

As described above, after the connection session is established, the target terminal obtains the connection device information of the iSCSI connection host by transmitting the report logic unit number command. Then, the initiator maps the connected devices corresponding to the same logical unit number to a unique mapping device through the configured device mapper, so as to avoid accessing different wired devices, but connect to the same logical unit number to access the same data. The situation.

The detailed description of the present invention and the detailed description of the present invention are set forth in the following detailed description of the embodiments of the present invention, which is to be understood by those skilled in the art to understand the technical contents of the present invention and to be implemented according to the present disclosure. The related objects and advantages of the present invention will be readily understood by those skilled in the art.

The objects and embodiments of the present invention are described in detail in the following preferred embodiments. However, the concepts of the present invention are also applicable to other ranges. The following examples are merely illustrative of the objects and methods of the present invention and are not intended to limit the scope thereof.

FIG. 1 is a flowchart of a method for multi-path accessing a remote logical device in a Linux system according to a preferred embodiment of the present invention. Referring to FIG. 1 , in this embodiment, a multi-path access to a remote logical device in a Linux system is used to implement a storage area network (SAN) between an initiator and a target end. Multipath access. First, the initiator establishes a communication connection with the target end (step S110). Then, the initiator requests to establish at least one connection session with the target end (step S120). Thereafter, the initiator obtains at least one iSCSI connection host allocated by the target end (step S130). Of course Then, the initiator obtains the connection device information corresponding to the SCSI connection host by transmitting the report logic unit number command (step S140). Finally, the initiator configures the device mapper to generate redundant device information according to the connection device and the corresponding logical unit number, and maps the redundant connection device to the mapping device (step S150), that is, forms a unique mapping. Device number (mapped LUN).

The procedure for establishing the communication connection between the initiator and the target is as follows: the initiator first transmits an iSCSI login request to the target. The target end resolves the security authentication and password parameters based on the iSCSI login request packet. When it is determined to be a legitimate user, the access request of the initiator is allowed. At this point, the target end returns an iSCSI login response packet to the initiator to establish a connection session. In this implementation, the communication connection is a communication connection established by using a TCP communication protocol. The communication connection can also be a UDP communication connection, and the scope is not limited herein.

The information of the piggybacked iSCSI packet (for example, iSCSI login request packet or iSCSI login response packet) transmitted by the initiator and the target terminal usually includes information such as the connection command and the connection status. When the communication connection is established, the initiator loads the report LUN command to the Command Description Block of the iSCSI packet. FIG. 2A is a schematic diagram of an iSCSI packet format according to a preferred embodiment of the present invention. Referring to FIG. 2A, the initiator encapsulates the command with the report unit of the report logic in the command description block and encapsulates it into the iSCSI data unit 250. Then, through the TCP data unit 240, the IP data unit 230, and the Ethernet roadmap header file 220, etc., the layer is encapsulated into a network packet 210, which is transmitted to the target end through the Internet. "Block 2B" is a schematic diagram of the iSCSI data unit containing fields in Figure 2A. Please refer to "Figure 2B" on the iSCSI data sheet. The element 250 further includes an iSCSI header file 252, an iSCSI control command 254, and a data content 256. The aforementioned return logic unit command number is written in the iSCSI control command 254 field, and all accessible logical unit numbers recorded in the target segment are written in the data content 256.

FIG. 3 is a schematic diagram of a system architecture for implementing multi-path access to a remote logical device in a preferred embodiment of the present invention. Please refer to "FIG. 3", the initiator 310 first establishes a TCP communication connection with the target terminal 320. After the communication connection is established, an attempt is made to establish a plurality of connection sessions with the target end 320. The initiator 310 transmits an iSCSI login request packet (Login Request PDU) to the target end, and requests to establish multiple communication connections. And the assigned iSCSI connection hosts 312, 314, and the corresponding logical unit numbers 322, 324 are obtained. The initiator sends the connection device information corresponding to the SCSI connection host by transmitting the iSCSI packet with the report logic unit number command, such as the type of the connection device, the speed and space of the stored data, or even the manufacturer of the connection device. , model and other information. In addition, the connection devices 312a and 312b corresponding to the connection host 312 and the connection devices 314a and 314b corresponding to the connection host 314 are obtained. After that, the initiator configures a device mapper, which compares the logical unit numbers 322 and 324 corresponding to the connection devices 312a, 312b, 314a, and 314b, and finds a connection corresponding to the same logical unit number. Line equipment. For example, if the logical unit number corresponding to the connection device 312a and the connection device 314a is the logical unit number 322, the connection device 312a and the connection device 314a are regarded as the same group of redundant devices. Similarly, the connection device 312b and the connection device 314b are regarded as the same group of redundant devices corresponding to the logical unit number 324. The device mapper records these redundant device information and maps these redundant wired devices to mapped devices (ie, mapped device numbers, mapped LUN). For example, the connection device 312a and the connection device 314a are set as the mapping device 332, and the connection device 312b and the connection device 314b are set as the mapping device 334. From "Figure 3", we can find access to two different mapping devices (332, 334), and finally access to different Logic Unit Numbers to avoid accessing the same logical unit number with different paths. The case where the same data is taken out occurs.

Since each mapping device includes multiple connection devices, and the logical unit number of the target end can be accessed through different connection sessions, the network can be used for the purpose of network offloading. For example, through the mapping device 332, the same logical unit number 322 can be accessed through different connection sessions established by different connection hosts (312, 314), thereby achieving the purpose of network traffic offloading. In addition, when traffic congestion occurs in a certain connection session, a network offloading method is performed to switch part of the traffic to another mapping device to balance the traffic load. When the connection dialog is interrupted, the original logical unit number can be accessed by another path by mapping the remaining redundant connection devices in the device, and the data packet transmission is continued to avoid the connection interruption.

While the present invention has been described above in terms of the preferred embodiments thereof, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. The scope of patent protection, therefore, the scope of patent protection of the present invention shall be defined by the scope of the patent application attached to the specification.

210‧‧‧Network packet

220‧‧‧Ethtonet signpost file

230‧‧‧IP data unit

240‧‧‧TCP data unit

250‧‧‧iSCSI data unit

252‧‧‧iSCSI header file

254‧‧‧iSCSI Control Instructions

256‧‧‧Information content

310‧‧‧Initiator

320‧‧‧ Target

330‧‧‧Device Mapper

312, 314‧‧‧Connected host

312a, 312b, 314a, 314b‧‧‧ connection equipment

322, 324‧‧‧ logical unit number

332, 334‧‧ ‧ mapping equipment

1 is a flow chart of a method for multi-path access to a remote logical device in a Linux system according to a preferred embodiment of the present invention.

FIG. 2A is a schematic diagram of an iSCSI packet format according to a preferred embodiment of the present invention.

Figure 2B is a schematic diagram of the iSCSI data unit containing fields in Figure 2A.

FIG. 3 is a schematic diagram of a system architecture for implementing a multi-path access remote logical device according to a preferred embodiment of the present invention.

Claims (7)

A multi-path access remote logical device in a Linux system, configured to implement a multi-path access logic device between an originating end and a target end of a storage area network, including: (a) an initiator and a target end are established a communication connection; (b) the initiator requires a plurality of conversations with the target end, wherein the step (b) further comprises: the initiator transmitting an internet small computer system interface (iSCSI) login request packet to the a target end; the target end determines, according to the one of the iSCSI login request packet parsing, a security authentication and a password parameter to allow the initiator to access the request; and returns an iSCSI login response packet to the initiator, and establishes the/the (c) the initiator obtains at least one iSCSI connection host allocated by the target end; (d) the initiator transmits at least one of the iSCSI connection hosts by transmitting a report logic unit number command a device for connecting the device; and (e) the initiator configures a device mapper to generate a redundant device information according to the/the wired device and the corresponding logical unit number, and the redundant device information Line equipment to a mapping device maps. The method of claim 1, wherein the communication protocol used to establish the communication connection is selected from a Transmission Control Protocol (TCP) protocol and a User Data Protocol (UDP) protocol. Any of the collections. The method of multi-path accessing a logical device according to claim 1, wherein the information of the iSCSI login response piggyback includes an allowable connection command and a connection status. The method of claim 1, wherein the report LUN command is loaded in a Command Description Block in an iSCSI packet. The method of multi-path accessing a logical device according to claim 1, wherein the redundant connection devices are connection devices that access the same logical unit number. The method of claim 1, wherein the device mapper includes performing a network offloading method to switch part of the traffic to another when traffic congestion occurs in one of the connection sessions. A mapping device equalizes the load. A method of multi-path accessing a logical device as described in claim 1, wherein the device mapper comprises switching the data packet to be transmitted by another mapping device when the connection sessions are interrupted.