Sans Digital iSCSI STORAGE User Manual page 9

Figure 1.4.1
This is the volume structure of Sans Digital 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. Each VD will be associated with one specific CV (Cache Volume) to execute the data
transaction. Each CV can have different cache memory size by user's modification/setting. LUN (Logical
Unit Number) is a unique identifier, in which users can access through SCSI commands.
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