4.17 Dynamic Logical Drive ExpansionWhat Is It and How Does It Work?
Before Dynamic Logical Drive Expansion, increasing the capacity of a RAID system using traditional methods meant backing up, re-creating and then restoring. Dynamic Logical Drive Expansion (a new feature in controller firmware versions 2.11 and later) allows users to add new SCSI hard disk drives and expand a RAID 0, 3 or 5 Logical Drive without powering down the system.
4.17.1 Two Modes of Dynamic Logical Drive Expansion
There are two modes of Dynamic Logical Drive Expansion.
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Mode 1 Expansion
involves adding more SCSI hard disk drives to a logical drive, which may
require that the user obtain an enclosure with more drive bays. The data
will be re-striped onto the original and newly added disks.
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As the figure
displays, new drives are added to increase the capacity of a 4-Gigabyte
RAID 5 logical drive. The two new drives increase the capacity to 8
Gigabytes (discounting one drive's capacity for storing parity data).
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Mode 2 Expansion, on
the other hand, requires the same number of higher-capacity SCSI hard disk
drives for a given logical drive.
The figure illustrates expansion of the same 4-Gigabyte RAID 5 logical drive using Mode 2 Expansion. Drives are copied and replaced, one by one, onto three higher-capacity drives.
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IMPORTANT:
The increased capacity from either expansion type will be a new partition.
Three new drives are scanned in (see section 4.6 for details on scanning in new drives.) To add the drives to the logical drive, select the logical drive where they will be added, then choose the Operation tab and Add Drive sub-tab. Select a drive to add and click the Add button. When you have selected all of the new drives you want to add, click OK.
The progress of the add process will be displayed as it is carried out.
The logical drive icon will appear to be degraded while the new drives are being added to the logical drive. The color will return to normal once the drive add is complete.
When you return to the partition table, you will notice that either partition 0 or the last partition will now be larger than before.
Follow the directions in section 4.12 to map the new partition to a host LUN. The new partition must be mapped to a host LUN in order for the HBA (host-bus adapter) to see it.