User guide

Hard Drive Arrays
Daz-9-14.EPS
Original
Logical
Drive
Added
Physical
Drives
Data from original logical drive redistributed over "Top" of all
physical drives.
New logical drive created over "Bottom" of all physical drives.
Figure E-10. Expanded array storage capacity with a second logical drive
For example Assume you have two Compaq RA4000(s), with a total of
10 drives; you want to expand this to the 12-drive maximum supported by one
RA4000 Controller. With Array Configuration Utility running, simply install
four matching drives in the empty drive bays. At this point, your array will
resemble Figure E-9, with the original data (original logical drive) represented
by the gray shaded drives and the new drives unshaded. Execute the Array
Configuration Utility, which is located on the Compaq SmartStart and Support
Software CD.
The RA4000 Controller then redistributes the data to an equal portion of all
the drives, using the same fault-tolerance method used originally. This is still
the first logical drive, but it now spans 12 drives instead of 10. The Array
Configuration Utility also detects the unused space on each drive (because
each drive contains 10/12ths of the data that it used to) 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 one, will be configured into a single array with more
total capacity than the original one. Now your array will look more like Figure
E-10 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 as best suits your needs.