Qsan Technology P300H61, Руководство пользователя

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The below graphic is the volume structure which QSAN 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 operations like read or
write. An initiator is usually located on the host side (either an iSCSI HBA or iSCSI SW
initiator).
RG
PD 2 PD 3 DS PD 1
VD 1 VD 2
QSnap
VD
RAM
Cache Volume
+
LUN 1 LUN 2 LUN 3
+
+