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Qsan Document – User Manual
Traditional Fat Provisioning
Thin provisioning sometimes is known as just-in-time capacity or over allocation. As the term
explains itself, it provides storage space by requests dynamically. Thin provisioning presents more
storage space to the hosts or servers connecting to the storage system than is actually available on
the storage system. Put it in another way, thin provisioning allocates storage space that may or
may not exist. The whole idea is actually another way of virtualization. Virtualization is always
about a logical pool of physical assets and provides better utilization over those assets. Here the
virtualization mechanism behind thin provisioning is storage pool. The capacity of the storage pool
is shared by all volumes. When write requests come in, the space will be drawn dynamically from
this storage pool to meet the needs.
Thin Provisioning
The Benefits of QThin
The benefits of QThin are described on the following.
Less disk purchase is needed initially when setting up a new storage system.
You don't need to buy more capacity to meet your future data growth at present time.
Usually hard drive price declines as time progresses. You can buy the same hard drives with
cheaper price at a later time. Why not save money upfront while you can?
No stranded storage capacity, better utilization efficiency and lower total cost of ownership.
QThin can make full use of the stranded capacity that traditional provisioning can't. All free
capacity can be made available to other hosts. A single storage system can serve more hosts
and servers to achieve high consolidation ratio. QThin can help you achieve the same level of
Actual data
(used)
Thin provisioning space
Available space
Physical space
Volume B
Whole
System
Disks not purchased
Volume A
Volume B
Volume A
Whole
System
Actual data
(used)
Available space
Physical space
