Logical Device Expansion (Lde) - Fujitsu ETERNUS DX80 S2 User Manual

Chapter 3 Setup
3.7 Optimizing Volume Configurations
• During RAID Migration, the access performance for the RAID groups that are specified as the RAID
Migration source and RAID Migration destination may be reduced.
• If the power is turned off or an electrical power outage occurs during RAID Migration, the process will
simply continue when the power is restored.
• When RAID Migration is used to increase the volume (LUN) capacities, note that the increased size of the
expanded volumes may not always be dynamically re-recognized by the server, depending on the server-
side OS (type and version) being used. Refer to the applicable OS and file system documentation before
dynamically expanding the volume capacity.
This is not necessary when building a new system after the volume capacity has been expanded.
3.7.2

Logical Device Expansion (LDE)

Logical Device Expansion (LDE) allows the capacity of an existing RAID group to be dynamically expanded by
the addition of extra drives. By expanding the capacity of existing RAID group, a new volume can be added
without having to add new RAID groups.
This section describes the restrictions and notes on using LDE.
For details on the LDE procedure, refer to "ETERNUS Web GUI User's Guide" or "ETERNUS CLI User's Guide".
• A RAID group can be specified as a target for LDE.
• Multiple LDEs cannot be performed simultaneously.
• LDE can be performed if the new RAID group capacity is the same or larger than the old capacity.
• Capacity expansion and changing the level of a RAID group can be performed at the same time.
• When adding drives, use drives that have the same capacity and speed as the drives that configure the
target RAID group. If drives of different capacities exist in a RAID group, the smallest capacity becomes the
standard for the RAID group after expansion, and all other drives are regarded as having the same capacity
as the smallest drive. In this case, the remaining drive space is not used. In addition, if drives of different
speeds exist in a RAID group, the access performance of the RAID group is reduced by the slower drives.
• If the drives that configure the target RAID group are SSDs, SSDs must be used when adding drives.
• If the drives that configure the target RAID group are SEDs, SEDs must be used when adding drives.
• LDE can be performed on a RAID group that contains an Advanced Copy target (copy source or copy
destination) volume.
• LDE cannot be performed on a RAID group that belongs to a Thin Provisioning Pool (TPP) or a Flexible Tier
Pool (FTRP).
• LDE cannot be performed for a RAID group in which a Wide Striping Volume (WSV) belongs.
• Since the data cannot be recovered after the failure of LDE, back up all the data of the volumes in the
target RAID group to another area before performing LDE. If LDE fails, recover using this backup data.
• Volumes cannot be added to the target RAID groups while LDE is running. Volumes can be added after LDE
is complete. Volumes cannot be deleted from the target RAID groups while LDE is running.
• If the power is turned off or an electrical power outage occurs during LDE, the process will simply continue
when the power is restored.
ETERNUS DX80 S2/DX90 S2 Disk storage system User's Guide -Operation-
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