User manual

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1.2.3 Volume relationship
The below graphic is the volume structure which RAG362 has designed. It
describes the relationship of RAID components. One RG (RAID group) consists of a
set of VDs (Virtual Disk) and owns one RAID level attribute. Each RG can be divided
into several VDs. The VDs in one RG share the same RAID level, but may have
different volume capacity. All VDs share the CV (Cache Volume) to execute the data
transaction. LUN (Logical Unit Number) is a unique identifier, in which users can
access through SCSI commands.
Figure 1.2.3.1
1.3 iSCSI concepts
iSCSI (Internet SCSI) is a protocol which encapsulates SCSI (Small Computer
System Interface) commands and data in TCP/IP packets for linking storage devices
with servers over common IP infrastructures. iSCSI provides high performance SANs
over standard IP networks like LAN, WAN or the Internet.
IP SANs are true SANs (Storage Area Networks) which allow several servers to
attach to an infinite number of storage volumes by using iSCSI over TCP/IP networks.
IP SANs can scale the storage capacity with any type and brand of storage system.
In addition, it can be used by any type of network (Ethernet, Fast Ethernet, Gigabit
Ethernet, and 10 Gigabit Ethernet) and combination of operating systems (Microsoft
Windows, Linux, Solaris, Mac, etc.) within the SAN network. IP-SANs also include
mechanisms for security, data replication, multi-path and high availability.
Storage protocol, such as iSCSI, has “two ends” in the connection. These ends are
initiator and target. In iSCSI, we call them iSCSI initiator and iSCSI target. The iSCSI
initiator requests or initiates any iSCSI communication. It requests all SCSI
RG
PD 2 PD 3 DS PD 1
VD 1 VD 2
iSnap
VD
RAM
Cache Volume
+
LUN 1 LUN 2 LUN 3
+
+
RAG362