Dell PowerVault ME4 Series Storage System Administrator’s Guide

About ADAPT

ADAPT is a RAID-based data protection level that maximizes flexibility, provides built in spare capacity, and allows for very fast rebuilds, large storage pools, and simplified expansion. All disks in the ADAPT disk group must be the same type (enterprise SAS, for example), and in the same tier, but can have different capacities. ADAPT is shown as a RAID level in the management interfaces.

ADAPT disk groups use all available space to maintain fault tolerance, and data is spread evenly across all of the disks. When new data is added, new disks are added, or the system recognizes that data is not distributed across disks in a balanced way, it moves the data to maintain balance across the disk group.

Reserving spare capacity for ADAPT disk groups is automatic since disk space dedicated to sparing is spread across all disks in the system. In the case of a disk failure, data will be moved to many disks in the disk group, allowing for quick rebuilds and minimal disruption to I/O.

The system will automatically default to a target spare capacity that is the sum of the largest two disks in the disk group, which is large enough to fully recover fault tolerance after loss of any two disks in the disk group. The actual spare capacity value can change depending on the current available spare capacity in the disk group. Spare capacity is determined by the system as disks are added to a disk group, or when disk groups are created, expanded, or rebalanced. For more information, see the topic about the add disk-group command in the Dell PowerVault ME4 Series Storage System CLI Guide.

ADAPT disk groups can be expanded to either replenish current target spare capacity or to increase usable capacity. For more information, see Expanding a disk group.

A system using ADAPT disk groups cannot be downgraded to a system that does not support ADAPT.