HP 3PAR StoreServ Concepts Guide: HP 3PAR OS 3.1.3

capability of TPVVs reduces the need for Dynamic Optimization to change the layout of TPVVs
after adding disks.
• Volume RAID level changes. Since different RAID levels have varying capacity requirements
and offer different degrees of performance, you may want to convert volumes from one RAID
type to another when system requirements change.
• Volume fault-tolerance changes. A volume with a cage-level availability can tolerate the failure
of a drive cage because its RAID sets use chunklets from different drive cages. A volume with
a magazine-level availability can tolerate the failure of a drive magazine because its RAID
sets use chunklets from different magazines. As applications and business requirements change,
it may be advantageous to update the fault-tolerance characteristics of existing virtual volumes.
• CPG and volume growth configuration changes. Changing the characteristics of CPGs and
changing virtual volume growth patterns can also reduce system performance over time. Tuning
optimizes the system layout by balancing the use of all available resources.
With dynamic optimization, you can manually change specific parameters on any specified virtual
volumes. This feature also analyzes your entire system and automatically corrects space usage
imbalances in the system. Virtual volume and physical disk capacity are analyzed and rebalanced
for optimal performance. The dynamic optimization automated tuning process has three phases:
1. Analyze the system and detect virtual volumes that are not correctly balanced between nodes.
If virtual volumes are not balanced correctly, the volumes are tuned to correct the imbalance.
This is the internode tuning phase.
2. Analyze the system and detect any chunklet imbalance between physical discs associated
with the same node. After the analysis, chunklets are moved from over-used physical disks to
under-used physical discs associated with the same node. This is the intranode tuning phase.
3. Analyze the system and verify that logical disks associated with a CPG have the same
characteristics as the CPG. If the LD characteristics do not match the CPG, the LD is modified
to match the CPG characteristics.
Dynamic Optimization tasks can be performed with both the HP 3PAR CLI and the HP 3PAR
Management Console. See the HP 3PAR Command Line Interface Administrator’s Manual and the
HP 3PAR Management Console Online Help for instructions on performing these tasks.
HP 3PAR System Tuner Software
HP 3PAR System Tuner Software is an optional feature that improves performance by identifying
over-used physical disks, and performing load balancing on those disks without interrupting access.
You must purchase the HP 3PAR System Tuner license to use this feature.
The HP 3PAR OS automatically creates a balanced system layout by mapping virtual volumes to
many logical disks, and creating logical disks from chunklets drawn from many physical disks. The
I/O for each volume is striped across many physical disks, increasing the throughput of the volume.
As the system grows and new applications are introduced, new storage usage patterns can emerge,
and the system performance can degrade. System Tuner maintains peak system performance by
automatically detecting and resolving bottlenecks without interrupting access.
If the performance of one or more physical disks degrades, the throughput of the logical disks is
reduced, and the entire system performance may decline. There are two general reasons why a
physical disk may have degraded performance:
• The physical disk has reached its maximum throughput due to an unbalanced load. A disk in
this state typically has unusually high average service times when compared to other disks.
• The physical disk is a bad disk. A bad disk typically has unusually high maximum service
times when compared to other disks.
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