001. iSCSI Introduction

I. iSCSI Introduction

Internet small computer system interface is an opportunity TCP/IP protocol, used to simulate SCSI high-performance local storage bus through an IP network, so as to provide data transmission and management for remote storage devices. As the San protocol, iSCSI expands the San across local and wide area networks, and provides location-independent data storage and retrieval through distributed servers and arrays.

2. Advantages of iSCSI

• San frees you from local cabling restrictions and facilitates storage integration between local and remote data centers;
• The iSCSI structure is logical. Only software configurations are used for new storage allocation, without additional cables and physical disks;
• Iscsi uses multiple remote data centers to simplify data replication, migration, and disaster recovery.

Basic Principles of three iSCSI

Iscsi mainly uses TCP/IP technology to form a server that can provide disks through the iSCSI target function, and then uses the iSCSI initiator (iSCSI initialization user) function, become a client that can be mounted to use iSCSI target, so that the disk can be applied through the iSCSI protocol.

Iscsi target: the storage device. It is a RAID device that stores disks. You can simulate a Linux host as an iSCSI target for use by other hosts;

ISCSI initiator: the disk service provided by target can be used only after the iSCSI initiator is used, usually a server.

Four iSCSI component terms

Terms	Description	Remarks
Starter	An iSCSI client is usually provided by software.	The initiator must be assigned a unique name (iqn)
Target	An iSCSI storage resource is configured for connections from the iSCSI server.	The target must be assigned a unique name (iqn)
ACL	Access permission Control List (multi-object ).	Use the node iqn (initiator name) to verify the permissions and restrictions of the initiator.
Found	Query the target server to list the configured targets.	Other access steps are required for the target user.
Iqn	Iscsi qualified name, a globally unique name, used to identify the initiator and target in a forced naming format.	Used to identify the initiator and target in a forced naming format. Iqn.YYYY-MM.com. reversed. Domain [: optional_string]
Login	Authenticate the target or lun to start using the client block device.
Lun	A logical unit. It is a block device with numbers. It is connected to a target and used by the target.	One or more Luns are connected to one target. One Target provides only one Lun.
Node	Any iSCSI initiator or iSCSI target is identified by its iqn.
Portal	The target or initiator is used to establish connections and IP addresses and ports.
TPG	Target portal group, a set of interface IP addresses and TCP ports that a specific iSCSI target will listen on.

001. iSCSI Introduction