HP (Hewlett-Packard) XP12000 User Manual

14

Auto LUN XP for the XP12000/XP10000

group B will probably decrease and I/O response time for parity group A might increase, while the overall 

throughput might increase or decrease.
From an open-system host, you can also use RAID Manager command to perform manual volume 

migration. To use RAID Manager to perform Auto LUN XP migration, install Auto LUN XP on the 

XP12000/XP10000. For more information, see ”

Automatic migration

Auto migration is the primary tuning method for disk arrays. Auto migration analyzes data and executes 

migration plans automatically based on user-specified parameters. Use Auto LUN XP to schedule auto 

migration operations, select data to be analyzed, and specify maximum time and performance impact of 

auto migration operations. Auto LUN XP displays a detailed log of auto migration activities.
Auto migration operations are based on the following major parameters:

•

Hierarchy of parity groups. Auto LUN XP arranges parity groups in the XP12000/XP10000 in a 

hierarchy based on HDD type, and assigns each parity group to a class based on performance of its 

HDD type. Classes are ordered from highest performance drive (class A) to lowest performance drive 

(class B, C, or higher depending on number of HDD types available). The auto migration function uses 

this hierarchy to identify target volumes for auto migration operations.
The auto migration function can also specify “fixed” parity groups that are excluded from auto 

migration operations. 

•

Maximum disk usage. The auto migration function specifies the maximum disk usage rate for each 

HDD class in the XP12000/XP10000, and uses these limits to identify source volumes for auto 

migration operations.
You must identify and specify disk usage limits for your environment. When you use the same maximum 

disk usage rate for all HDD classes, HDD performance is the only factor used in determining auto 

migration plans. When you specify different usage limits for HDD classes, you can bias the auto 

migration function to favor (or avoid) certain HDD types. Migrating high-usage volumes to higher HDD 

classes should significantly improve host access to volumes, which can also have a large effect on disk 

array performance.
The auto migration function also specifies the maximum disk usage rate during auto migration 

operations, so you can control the impact of Auto LUN XP copy operations on disk array performance. 

If source or target parity group usage exceeds the specified limit during migration, the auto migration 

operation is canceled.

Do not perform manual migration operations while the auto migration function is active. Always turn off the 

auto migration function and cancel any existing auto migration plan before performing manual migration 

operations.

Storage management by maximum disk usage

Use the auto migration function to specify maximum usage rate for each HDD class in an 

XP12000/XP10000. When a parity group exceeds this limit, the auto migration function makes a plan to 

migrate one or more volumes in this parity group to a parity group in a higher HDD class or to a parity 

group in the same HDD class with lower usage. 
This storage tuning method addresses and can eliminate disk drive activity bottlenecks. Auto LUN XP uses 

its estimated usage rates to verify each proposed auto migration, and will not perform a migration 

operation that might result in a target parity group exceeding the user-specified maximum disk usage rate.
The auto migration function identifies parity groups that exceed the user-specified usage limit, and selects 

high-usage volumes as source volumes to be migrated to parity groups in higher HDD classes or to other 

parity groups in the same HDD class with lower usage.

Keep reserved volumes in high HDD classes

When parity groups in the highest HDD classes start to run out of reserved (empty) volumes, Auto LUN XP 

maintains available reserve volumes by automatically migrating low-usage volumes from higher HDD class 

groups to lower HDD class groups.