HP P6000 - Manual (Page 34)

space allocated does not need to be contiguous. In the event that the allocated capacity reaches
the physical disk capacity, the write operation fails.
Thin provisioned virtual disks differ from standard virtual disks as follows:
Standard virtual disk Thin provisioned disk
Requires the full amount of physical disk space to be
allocated at all times The amount of physical disk space allocated can
automatically change in response to the amount of data
being stored, up to the specified size of the virtual disk or
until all available disk space is used
Must be explicitly resized whenever the amount of disk
space needs to be changed Does not require explicit resizing (manually or with scripts)
Physical disk space that is allocated but unused can create
stranded capacity Has no unused physical disk space
The requested capacity is limited by the amount of
available physical disk capacity that can be allocated The maximum requested capacity can exceed the amount
of available physical disk capacity that can be allocated
The following example demonstrates thin provisioning:
A storage administrator is planning to create two virtual disks for two new host applications. His
HP P6000 storage system currently has a total capacity of 10 TB, with 6 TB unused disk space.
The administrator determines that each host application initially requires 2 TB of disk space, but
eventually, the host applications will require 4 TB of space. With these requirements in mind, the
administrator creates two 4 TB thin provisioned virtual disks.
Each host application recognizes a 4 TB virtual disk, even though initially only 2 TB of physical
disk space is allocated. As the amount of stored data increases, the storage system automatically
allocates more space (up to the 4 TB maximum size). And, even though only 6 TB of space is
available on the storage system, the administrator is able to add 2 virtual disks with a total potential
capacity of 8 TB.
Allocation alarms and email notification are used by the administrator to monitor data increases
and send email notifications.
You can use SSSU to view the amount of virtual disk space that is allocated and used.
NOTE: SSSU displays the percentage of allocated space used. This allocation level is rounded
down to the whole number.
34 Provisioning storage