3.2 Operations Optimization (Virtualization)
The Thin Provisioning function can be used for disk virtualization. This function reduces the initial cost by
optimizing the usability of physical capacity. The power consumption requirements can also be reduced be-
cause a fewer number of drives are installed.
A single controller configuration differs from a dual controller configuration in the following ways:
•
The Thin Provisioning function cannot be used.
3.2.1 Thin Provisioning
The Thin Provisioning function sets virtually-available capacity regardless of the actual physical capacity that
is registered.
In an environment where the Thin Provisioning function is used, the capacity is allocated to virtual volumes
instead of physical disks to meet user's requests. Physical disks are managed as a shared disk pool. Physical
disks are allocated a capacity that is in proportion to the amount of data that is written to the virtual volume.
This enables efficient usage of physical disks by making sure that there are no unused physical disks.
A threshold for a physical disk pool to prevent any capacity shortage and a function that automatically noti-
fies the administrator when the threshold is reached enable drives to be added when needed.
Figure 3.6 Example of Thin Provisioning
Although the disk usage rate differs for each volume,
the free area of these volumes cannot be shared.
Used area
Free area
Vol.1
Vol.1 to Vol.3 Used area
Free area
Vol.2 Vol.3
The physical disk can be managed by a pool, and unused
capacity is shared with virtual volumes that belong to the
pool.
Conventional way Thin Provisioning
Free area in the physical disk
is shared with each volume.
Chapter 3 Functions
3.2 Operations Optimization (Virtualization)
29
FUJITSU Storage ETERNUS DX60 S3 Disk storage system
Overview
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