HP Integrity rx4640 Server - Manual (Page 26)

Replacing, moving, or adding hard drives 26
If another drive in the array fails while fault tolerance is unavailable during rebuild, a fatal system error
may occur, and all data on the array is then lost. In exceptional cases, however, failure of another drive
need not lead to a fatal system error. These exceptions include:
• Failure after activation of a spare drive
• Failure of a drive that is not mirrored to any other failed drives (in a RAID 1+0 configuration)
• Failure of a second drive in a RAID ADG configuration
Time required for a rebuild
The time required for a rebuild varies considerably, depending on several factors:
• The priority that the rebuild is given over normal I/O operations (you can change the priority setting
by using ACU)
• The amount of I/O activity during the rebuild operation
• The rotational speed of the hard drives
• The availability of drive cache
• The brand, model, and age of the drives
• The amount of unused capacity on the drives
• The number of drives in the array (for RAID 5 and RAID ADG)
Allow approximately 15 minutes per gigabyte for the rebuild process to be completed. This figure is
conservative, and newer drive models usually require less time to rebuild.
System performance is affected during the rebuild, and the system is unprotected against further drive
failure until the rebuild has finished. Therefore, replace drives during periods of low activity when
possible.
CAUTION: If the Online LED of the replacement drive stops blinking and the amber Fault LED glows, or if
other drive LEDs in the array go out, the replacement drive has failed and is producing unrecoverable disk
errors. Remove and replace the failed replacement drive.
When automatic data recovery has finished, the Online LED of the replacement drive stops blinking and
begins to glow steadily.
Failure of another drive during rebuild
If a non-correctable read error occurs on another physical drive in the array during the rebuild process,
the Online LED of the replacement drive stops blinking and the rebuild abnormally terminates.
If this situation occurs, reboot the server. The system may temporarily become operational long enough to
allow recovery of unsaved data. In any case, locate the faulty drive, replace it, and restore data from
backup.
Upgrading hard drive capacity
You can increase the storage capacity on a system even if there are no available drive bays by swapping
drives one at a time for higher capacity drives. This method is viable as long as a fault-tolerance method
is running.
CAUTION: Because it can take up to 15 minutes per gigabyte to rebuild the data in the new configuration,
the system is unprotected against drive failure for many hours while a given drive is upgraded. Perform drive
capacity upgrades only during periods of minimal system activity.
To upgrade hard drive capacity:
1. Back up all data.