Dell PowerVault MD3000i Hardware Owner's Manual

Also see for PowerVault MD3000i: Getting started Tuning guide System installation guide User guide Information update

Contents

Dell PowerVault MD3000i Hardware Owner's Manual Manual pdf 50 page image

50 Using Your RAID EnclosurePreferred and Alternate Controllers and PathsA preferred controller is a RAID controller module designated as the owner ofa virtual disk or disk group. The preferred controller is automatically selectedby MD Storage Manager when a virtual disk is created. You can change thepreferred RAID controller module owner of a virtual disk after it is created.Ownership of a virtual disk is moved from the preferred controller to thesecond controller (also called the alternate controller) when the preferredcontroller is:• Physically removed• Updating firmware• Involved in a fatal event that caused failover to the alternate controllerPaths used by the preferred controller to access either the disks or the hostserver are called the preferred paths; redundant paths are called the alternatepaths. If a failure causes the preferred path to become inaccessible, thestorage array automatically uses the alternate path to access data.When a RAID Controller Module Is Replaced or RemovedWhen one RAID controller module fails, or is removed from the RAIDenclosure, failover software on the host server directs the alternate RAIDcontroller module to assume all controller responsibilities for the storagearray. The virtual disks owned by the failed or removed RAID controllermodule are failed over to the surviving controller and no data is lost.NOTE: For Linux kernels, stop and then restart the SMagent after moving acontroller offline, replacing a controller, or configuring iSCSI connections.Because host-based multi-path software is configured for automatic failback,the data paths and virtual disks are restored to their original RAID controllermodule after the RAID controller module is replaced.Automatic failback occurs under the following conditions:• Data is protected by dual redundant paths to the host server.• The host server has multi-path failover software installed, and it isconfigured for auto failback.