Dell PowerVault ME5 Series Administrator's Guide

Linear disk group configuration

A linear disk group requires the specification of a set of disks, RAID level, disk group type, and a name.

Whenever the system creates a linear disk group, it also creates an identically named linear pool at the same time. No further disk groups can be added to a linear pool.

During onboarding, you were allowed to use the Linear version of the Add Disk Group modal to configure disk groups. If you deferred the disk group configuration option during onboarding, manual configuration is available.

The Add Disk Group action (Maintenance > Storage > Pool Configuration) enables manual configuration of disk groups. Disk group configuration requires you to enter a specified name, assigned controller, and protection (RAID) level.

The Add Disk Group panel is dynamic, displaying configuration options based on the RAID level selected and the available disks on the system. Available disks are listed in the middle panel, and the summary panel will update as you select disks. The disk group will be added to the pool once you complete your selections and choose Add Disk Group.

The RAID levels for linear disk groups created through the PowerVault Manager must be fault tolerant. The supported RAID levels for linear disk groups in the interface are: RAID 1, RAID 5, RAID 6, RAID 10, ADAPT. RAID 10 appears in the interface only if the system disk configuration supports it. If RAID 10 is specified, the disk group has a minimum of two subgroups. Additionally, you can create non-fault-tolerant NRAID or RAID-0 disk groups through the CLI

For maximum performance, all of the disks in a linear disk group must share the same classification, which is determined by disk type, size, and speed. This provides consistent performance for the data being accessed on that disk group.

Each time that the system adds a linear disk group, it also creates a corresponding pool for the disk group. Once a linear disk group and pool exists, volumes can be added to the pool. The volumes within a linear pool are allocated in a linear/sequential way, such that the disk blocks are sequentially stored on the disk group.

Linear storage maps logical host requests directly to physical storage. In some cases the mapping is 1-to-1, while in most cases the mapping is across groups of physical storage devices, or slices of them.

To remove a linear disk group, delete the disk group and the contained volumes are automatically deleted. The disks that compose that linear disk group are then available to be used for other purposes.

If the owning controller fails, the partner controller assumes temporary ownership of the disk groups and resources owned by the failed controller. If a fault-tolerant cabling configuration, with appropriate mapping, is used to connect the controllers to hosts, LUNs for both controllers are accessible through the partner controller so I/O to volumes can continue without interruption.