DELL MD3220 사용자 설명서

Planning: MD3200 Series Storage Array Terms and Concepts

A preferred controller is a RAID controller module designated as the owner of 

a virtual disk or disk group. The preferred controller is automatically selected 

by MDSM when a virtual disk is created. You can change the preferred RAID 

controller module owner of a virtual disk after it is created. If a host is only 

connected to only one RAID controller module, the preferred owner must 

manually be assigned to the RAID controller module the host can access.
Ownership of a virtual disk is moved from the preferred controller to the 

secondary controller (also called the alternate controller) when the preferred 

controller is:

• Physically removed 
• Updating firmware 
• Involved in an event that caused failover to the alternate controller 

Paths used by the preferred RAID controller module to access either the disks 

or the host server are called the preferred paths; redundant paths are called 

the alternate paths. If a failure causes the preferred path to become 

inaccessible, the storage array automatically uses the alternate path to access 

data, when this occurs the enclosure status LED blinks amber.

MDSM can be used to automatically build and view virtual disks. It uses 

optimal settings to stripe the disk group. Virtual disks are assigned to 

alternating RAID controller modules when they are created. This default 

assignation provides a simple means for load balancing the workload of the 

RAID controller modules.
Ownership can later be modified to balance workload according to actual 

usage. If virtual disk ownership is not manually balanced, it is possible for one 

controller to have the majority of the work, while the other controller is idle. 

Limit the number of virtual disks in a disk group. If multiple virtual disks are 

in a disk group, consider:

• The impact each virtual disk has on other virtual disks in the same disk 

group.

• The patterns of usage for each virtual disk.
• Different virtual disks have higher usage at different times of day.

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