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E-20 Understanding Drive Arrays
Writer: Rickard Project: Compaq Smart Array 3200 Controller Reference Guide Comments: 340862-002
File Name: L-APPE.DOC Last Saved On: 12/7/98 9:30 AM
COMPAQ CONFIDENTIAL - NEED TO KNOW REQUIRED
The Smart Array 3200 Controller equally redistributes the data to all the drives,
using the same fault-tolerance method as the original configuration. The first
logical drive remains first, but it now spans 14 drives instead of 10. The Array
Configuration Utility also detects the unused space on each drive (because each
drive contains 10/14ths of the data it used to contain) and helps you configure it
into a second logical drive with its own fault tolerance distributed over the extra
space of all the drives.
When this process is finished, both logical drives,–,one containing the original
data and the new empty drive,–,will be configured into a single array with more
total capacity than the original drive. Now your array will resemble
Figure D-11, using the same shading scheme to represent the logical drives.
It is not necessary for all logical drives in an array to be the same size or even
have the same fault-tolerant configuration. Each logical drive is treated as a
separate entity no matter how many physical drives it crosses. Each may be
configured to best suit your needs.
It is important to remember that all physical drives in an array should be the
same size (capacity). This is because each drive contains an equal portion of one
or more logical drives and the portion sizes can only total the size of the
smallest drive. While you are not prevented from expanding storage capacity
with larger drives, the extra space cannot be used.
During expansion of an array that initially has two or more logical drives,
redistribution of data takes place one logical drive at a time. When the capacity
expansion has completed, any newly created logical drive will become
available. Under Windows NT and NetWare, the new logical drive can then be
appended to your existing logical volume.