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Figure 2: Virtual disks are created
In Figure 3, the free space of "Fat-RG" immediately reduces to 862GB. 1000GB is taken
away by the virtual disk. However, the free space of "Thin-RG" is still 1862GB even though
the same size of virtual disk is created from the RAID group. Nothing is written to the virtual
disk yet, so no space is allocated. The remaining 1862GB can be used to create other virtual
disks. This is storage efficiency.
Figure 3: Write on demand
Expand capacity on demand without downtime.
Extra RAID set can be added to the thin RAID group to increase the size of free storage pool.
A thin RAID group can have up to 32 RAID sets with each RAID set containing up to 64
physical hard drives. The maximum size of each RAID set is 64TB. Figure 4 shows that "Thin-
RG" consists of two RAID sets.
Figure 4: Scalable RAID group size
Allocation unit (granularity) is 1GB. This is a number that demands careful balance between
efficiency and performance. The smaller it is, the better the efficiency and the worse the
performance becomes, and vice versa.
Thin provisioned snapshot space and it is writable.
Snapshot space sits at the same RAID group of the volume that the snapshot is taken against.
Therefore when you expose the snapshot into a virtual disk, it becomes a thin-provisioned
