Effects of a hard drive failure, Compromised fault tolerance, Recovering from compromised fault tolerance – HP D6000 Disk Enclosure User Manual
Page 31
Troubleshooting 31
CAUTION:
Sometimes, a drive that has previously failed 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.
Effects of a hard drive failure
When a hard drive fails, all logical drives that are in the same array are affected. Each logical drive in an
array may be using a different fault-tolerance method, so each logical drive can be affected differently.
•
RAID 0 configurations cannot tolerate drive failure. If any physical drive in the array fails, all
non-fault-tolerant (RAID 0) logical drives in the same array will also fail.
•
RAID 1+0 configurations can tolerate multiple drive failures as long as no failed drives are mirrored to
one another (with no spares assigned).
•
RAID 5 configurations can tolerate one drive failure (with no spares assigned).
•
RAID 6 with ADG configurations can tolerate simultaneous failure of two drives (with no spares
assigned).
Compromised fault tolerance
CAUTION:
When fault tolerance is compromised, data loss can occur. However, it may be
possible to recover the data. For more information, see "Recovering from compromised fault
tolerance (refer to "
" on page
)."
If more drives fail than the fault-tolerance method can manage, fault tolerance is compromised, and the
logical drive fails. If this failure occurs, the operating system rejects all requests and indicates unrecoverable
errors.
For example, fault tolerance might occur when a drive in an array fails while another drive in the array is
being rebuilt.
Compromised fault tolerance can also be caused by problems unrelated to drives. In such cases, replacing
the physical drives is not required.
Recovering from compromised fault tolerance
If fault tolerance is compromised, inserting replacement drives does not improve the condition of the logical
volume. Perform the following procedure to recover data:
1.
Check for loose, dirty, broken, or bent cabling and connectors on all devices.
2.
Power down the D6000 ("
" on page
3.
Power up the D6000 ("
" on page
In some cases, a marginal drive is operational long enough to allow backup of important files.
4.
Make copies of important data, if possible.
5.
Replace any failed drives.