HP A7143A RAID160 SA Controller Support Guide, February 2007

Hard Drive Installation and Replacement
General Aspects of Disk Drive Replacement
Appendix C
106
General Aspects of Disk Drive Replacement
CAUTION Sometimes, a disk drive that has previously been failed by the controller may seem to be
operational after the system is power-cycled, or (for a hot-pluggable drive) after the drive has
been removed and reinserted. However, continued use of such marginal drives may eventually
result in data loss. Replace the marginal drive as soon as possible.
There are several other factors to remember when replacing a disk drive:
• Non-hot-pluggable drives should only be replaced while the system is powered down.
• Hot-pluggable drives can be removed and replaced at any time, whether the host or storage system power
is on or off.
• When a hot-pluggable drive is inserted, all disk activity on the array pauses while the new drive is
spinning up (usually 20 seconds or so). If the drive is inserted while power is on, in a fault-tolerant
configuration, data recovery onto the replacement drive begins automatically (indicated by the blinking
Online LED).
• Replacement disk drives must have a capacity no less than that of the smallest disk drive in the array.
Drives of insufficient capacity will be failed immediately by the controller, before automatic data recovery
can begin.
CAUTION In systems using external data storage, take care that the server is the first unit to be powered
down and the last to be powered back up. Doing this ensures that the system will not
erroneously mark the drives as failed.
The rebuild operation takes several hours, even if the system is not busy while the rebuild is in progress.
System performance and fault tolerance are both affected until the rebuild has finished. Therefore, replace
drives during low activity periods whenever possible. In addition, be sure that all logical drives on the same
array as the disk drive being replaced, have a current, valid backup.