HP StorageWorks 500 Modular Smart Array - Manual (Page 139)

Troubleshooting
D-6 HP StorageWorks Modular Smart Array 500 System User Guide
Recovering from Hard Drive Failure
CAUTION: Back up all data before removing drives or changing configurations.
Failure to do so could result in permanent loss of data. Before moving drives and
arrays, run ACU 6.0.
The purpose of fault-tolerant configurations on the HP MSA500 controller is to
protect against data loss due to drive failure. Although the MSA500 controller
firmware is designed to protect against normal drive failure, you must perform the
correct actions to recover from a drive failure without inadvertently inducing any
additional drive failures. Multiple drive failures in the same array generally result in
data loss (exceptions include failures following activation of a spare drive, and failure
of drives in a mirroring configuration that are not mirrored to one another or ADG
configuration).
Drives may be either Ultra2 or Ultra 3 hot-plug universal hard disk drives. When
grouping drives in an array, always use drives of the same capacity. The array cannot
use the excess capacity of a larger drive, so this capacity is ignored and wasted.
A list of supported hard drives is available at the HP website
www.hp.com/products/sharedstorage
Hard Drive Failure
When a hard drive fails, all logical drives in the same array are affected. Each logical
drive in an array may be using a different fault tolerance method, so the effect on
each logical drive can be different.
• RAID 0 configurations cannot tolerate drive failure. If any physical drive in the
array fails, the controller fails all non-fault-tolerant (RAID 0) logical drives in the
same array.
• RAID 1 configurations can tolerate multiple drive failures as long as no failed
drives are mirrored to one another.
• RAID 5 configurations can tolerate one drive failure.
• RAID ADG configurations can tolerate simultaneous failure of two drives in the
array.