Note: this refers to concepts when using Coraid's EtherDrive VSxx VirtualStorage Appliance)

Step #1 - Physical Volumes

• Physical disks are assembled into Physical Volumes (physical LUNs) inside the EtherDrive SRxxxx storage appliance. Each Physical Volume (PV) is just a raw block storage device with a large number of 512 byte sized locations where data can be stored. (ie. each block location can hold 512 bytes of data). These block locations (also called LBA or Logical Block Address) are uniquely numbered (ie. LBA#1 through ~1,953,125,000 for a 1TB volume).
• Creating LUNs (PV's) is done on the SR by using the configuration commands to "make" RAID volumes. This is defined in the SR software manual

Step #2 - Volume Groups

• Volume Groups (VG's) are created by assigning PV's to the VG. During the process of adding the PV to the VG, each PV is carved up into small chunks called Physical Extents (PE's).
• You can set the size of a PE to 4, 8, 16 or 32MBytes. Why divide the PV into PE's? Because this give you a way to create Logical Volumes (step #3 below) of any size down to the size of one PE and up to as much storage as you need.
• Creating Volume Groups is done in the EtherDrive VSxx VirtualStorage Appliance, using the configuration commands as define in the VS software manual.
• VG's can have PV members from any AoE device on the SAN (ie. a VG can include PV's from many SR storage units). Each PV can be assigned to one, and only one VG.