Installation guide

Glossary
Manual No. 775007 G-9
Standard Disk Drive
This term refers to a hard disk drive with SCSI, IDE, or other interface, that
is attached to the host system through a standard disk controller.
Standby Replacement of Disks (“Hot Spare”)
The “Standby Replacement” (or “Hot Spare”) is one of the most important
features the controller provides to achieve automatic, non-stop service with a
high degree of fault-tolerance. The rebuild operation will be carried out by
the controller automatically when a SCSI disk drive fails and both of the
following conditions are true:
• A “standby” SCSI disk drive of identical size is found attached to the
same controller;
• All of the system drives that are dependent on the failed disk are
redundant system drives, e.g., RAID 1, RAID 3, RAID 5, RAID 0+1.
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Note
The standby rebuild will only happen on the SAME
DAC960 controller, never across DAC960 controllers.
A “Standby” disk can be created in one of two ways:
4. When a user runs DACCF utility, all disks attached to the controller
that are NOT configured into any drive group will be automatically
labeled as “standby” drives.
5. A disk may also be added (attached at a later time) to a running system
and labeled as standby by using the “DAC960 Software Kit” (see
appropriate chapters for DAC960 utilities for a particular operating
system).
During the automatic rebuild process, system activity continues as normal.
System performance may degrade slightly during the rebuild process.
To use the standby rebuild feature, you should always maintain a standby
SCSI disk in your system. When a disk fails, the standby disk will
automatically replace the failed drive and the data will be rebuilt. The system
administrator can disconnect and remove the bad disk and replace it with a
new disk. The administrator can then make this new disk a standby.