HP 3PAR Management Console 4.5.1 Software User Guide

29 Tuning the System
The Tune System feature allows you optimize system performance by reallocating space for virtual
volumes and logical disks, and reallocating chunklets across physical disks.
Tune System runs only for those domains you are authorized. If you do not have authorization for
all domains, intranode and chunklet level tuning fails.
There are three possible types of tunes, all of which run as a background task:
• “Tune System” (page 459) – Detects physical disk space usage imbalance between nodes and
rebalances virtual volumes between nodes, detects newly added disks and rebalances chunklets
from a node's existing physical disks to its under-allocated ones, and performs a re-layout of
LDs whose characteristics do not match their parent CPG.
NOTE: Tuning a system can take anywhere from a few hours to several days. If the System
has restarted during that time, you might not see the task information, and you should check
the log for failures.
• “Tune CPGs” (page 463) – Performs the same task as Tune system but limits the retuning to a
specific CPG.
• “Tune Physical Disk Chunklets Only” (page 464) – (Option available for 3.1.2 systems only.)
Rebalances a node's physical disks at the chunklet level. This option is aimed at systems where
new disks have been added to a node. It is run on a per-node basis.
NOTE: Virtual volumes associated with CPGs in Adaptive Optimization configurations are not
tuned by Tune System.
Tune System
The tuning process is slightly difference for 3.1.1 and 3.1.2 systems. Procedural instructions for
both systems are provided.
To access the Tune system feature:
1. Select Provisioning in the Manager Pane.
2. Click Tune System in the Common Actions panel.
The Tune System wizard appears.
3. Select the system you want to tune from the System list.
4. Select the Tune system radio button.
Follow the instructions related to your system:
“Tuning HP 3PAR OS 3.1.2 Systems” (page 459)
“Tuning HP 3PAR OS 3.1.1 Systems” (page 461)
Tuning HP 3PAR OS 3.1.2 Systems
With 3.1.2 systems there are three types of tunes available: Tune system, Tune CPGs, and Tune
physical disk chunklets only.
When Tune system is selected, you have the option of changing the following settings:
• Volume Allocation Imbalance Threshold – The percentage above the average space allocated
across nodes at which a volume is considered out of balance.
• Chunklet Allocation Imbalance Threshold – The percentage above the average (for physical
disks of one device type on a single node) at which the number of chunklets allocated to a
physical disk is considered out of balance.
Tune System 459