HP XP7 Storage - Manual (Page 12)

Thin Provisioning Overview
Thin provisioning is an approach to managing storage that maximizes physical storage capacity.
Instead of reserving a fixed amount of storage for a volume, it simply assigns capacity from the
available physical pool when data is actually written to disk.
Thin provisioning includes:
•
“Thin Provisioning Z concepts ” (page 12)
Thin Provisioning Z
Though basic or traditional provisioning strategies can be appropriate and useful in specific
scenarios, they can be expensive to set up, awkward and time consuming to configure, difficult to
monitor, and error prone when maintaining storage.
Although Thin Provisioning Z requires some additional steps, it is a simpler alternative to the
traditional provisioning methods. It uses thin provisioning technology that allows you to allocate
virtual storage capacity based on anticipated future capacity needs, using virtual volumes instead
of physical disk capacity.
Overall storage use rates may improve because you can potentially provide more virtual capacity
to applications while using fewer physical disks. It can provide lower initial cost, greater efficiency,
and storage management freedom for storage administrators. In this way, Thin Provisioning Z
software:
•
Simplifies storage management
•
Provides balanced resources and more optimized performance by default without inordinate
manual intervention.
•
Maximizes physical disk usage
•
May reduce device address requirements over traditional provisioning by providing larger
volume sizes.
Thin Provisioning Z concepts
Thin Provisioning Z is a volume management feature that allows storage managers and system
programmers to efficiently plan and allocate storage to users or applications. It provides a platform
for the array to dynamically manage data and physical capacity without frequent manual
involvement.
Thin Provisioning Z provides three important capabilities: thin provisioning of storage, enhanced
default volume performance, and larger volume sizes.
Thin Provisioning Z is more efficient than traditional provisioning strategies. It is implemented by
creating one or more Thin Provisioning Z pools (THP pools) of physical storage space using multiple
LDEVs. Then, you can establish virtual THP volumes (THP V-VOLs) and connect them to the individual
THP pools. In this way, capacity to support data can be randomly assigned on demand within the
pool.
THP V-VOLs are of a user-specified logical size without any corresponding physical space. Actual
physical space (in 38-MB pool page units) is automatically assigned to a THP V-VOL from the
connected THP pool as that volume’s logical space is written to over time. A new volume does not
have any pool pages assigned to it. The pages are loaned out from its connected pool to that THP
volume until the volume is reformatted or deleted. At that point, all of that volume’s assigned pages
are returned to the pool’s free page list. This handling of logical and physical capacity is called
thin provisioning. In many cases, logical capacity will exceed physical capacity.
Thin Provisioning Z enhances volume performance by default. This is an automatic result of how
THP V-VOLs map capacity from individual THP pools. A pool is created using from one to 1024
LDEVs (pool volumes) of physical space. Each pool volume is sectioned into 38-MB pages. Each
page is consecutively laid down on a number of RAID stripes from one pool volume. The pool’s
12 Introduction to provisioning