Optimization of Volume Configurations

The ETERNUS DX allows for the expansion of volumes and RAID group capacities, migration among RAID groups, and changing of RAID levels according to changes in the operation load and performance requirements while the system is running. There are several expansion functions.

Table: Optimization of Volume Configurations

Function/usage

Volume expansion

RAID group expansion

Migration among RAID groups

Changing the RAID level

Striping for RAID groups

RAID Migration

¡ (Adding capacity during migration) (*1)

×

¡

¡

×

Logical Device Expansion

×

¡

×

¡ (Adding drives to existing RAID groups)

×

LUN Concatenation

¡ (Concatenating free spaces)

×

×

×

×

Wide Striping

×

×

×

×

¡

¡: Possible, ×: Not possible

*1 : 

For TPVs or FTVs, the capacity cannot be expanded during a migration.

Expansion of Volume Capacity

  • RAID Migration (with increased migration destination capacity)

    When volume capacity is insufficient, a volume can be moved to a RAID group that has enough free space. This function is recommended for use when the desired free space is available in the destination.

  • LUN Concatenation

    Adds areas of free space to an existing volume to expand its capacity. This uses free space from a RAID group to efficiently expand the volume.

Expansion of RAID Group Capacity

  • Logical Device Expansion

    Adds new drives to an existing RAID group to expand the RAID group capacity. This is used to expand the existing RAID group capacity instead of adding a new RAID group to add the volumes.

Migration among RAID Groups

  • RAID Migration

    The performance of the current RAID groups may not be satisfactory due to conflicting volumes after performance requirements have been changed. Use RAID Migration to improve the performance by redistributing the volumes amongst multiple RAID groups.

Changing the RAID Level

  • RAID Migration (to a RAID group with a different RAID level)

    Migrating to a RAID group with a different RAID level changes the RAID level of volumes. This is used to convert a given volume to a different RAID level.

  • Logical Device Expansion (and changing RAID levels when adding the new drives)

    The RAID level for RAID groups can be changed. Adding drives while changing is also available. This is used to convert the RAID level of all the volumes belonging to a given RAID group.

Striping for Multiple RAID Groups

  • Wide Striping

    Distributing a single volume to multiple RAID groups makes I/O access from the server more efficient and improves the performance.