Dell PowerVault ME5 Series Administrator's Guide

Disk group expansion

You can expand the capacity of an existing linear disk group. The RAID protection level determines whether the disk group can be expanded and the maximum number of disks the disk group can have. This task cannot be performed on an NRAID or RAID-1 disk group. Host I/O to the disk group can continue while the expansion proceeds.

Virtual disk-group expansion is only available with the ADAPT protection level. An ADAPT virtual disk group can consist of 12–128 disks of the same type. Host I/O to the disk group can continue while the expansion proceeds. This task cannot be performed on a non-ADAPT virtual disk group.

When expanding a disk group, all disks in the group must be the same type (enterprise SAS, for example). Disk groups support a mix of 512n and 512e disks. However, for best performance, all disks should use the same sector format. For more information about disk groups, see Disk groups.

ADAPT disk groups are expanded when disks are added to the group. The controller determines how the additional disks are used, either to replenish spare capacity to equal target capacity, to increase usable capacity, or both.

For ADAPT disk groups, expansion is very fast. The controller invokes rebalance to redistribute spare capacity evenly across all disk members of the group to allow uniformly distributed usable capacity. Due to the possible need to rebalance, and to maintain fault tolerance and target spare capacity, any new usable capacity may not be immediately available. Monitor the Activity panel for progress on these activities, and check for updated usable capacity when the activities are complete. When set to the default spare capacity, the system will try to replenish spare capacity to be the sum of the largest two disks in the group.

In the Maintenance > Storage panel, locate the ADAPT disk group to expand, access its slide-over panel, click Expand Disk Group, and follow the on-screen directions.