Automatic Data Recovery (Rebuild) - HP Smart Array P430 series Benutzerhandbuch

In some situations, you can replace more than one drive at a time without data loss. For example:
•
In RAID 10 configurations, drives are mirrored in pairs. You can replace several drives
simultaneously if they are not mirrored to other removed or failed drives.
•
In RAID 50 configurations, drives are arranged in parity groups. You can replace several drives
simultaneously, if the drives belong to different parity groups. If two drives belong to the same parity
group, replace those drives one at a time.
•
In RAID 6 configurations, you can replace any two drives simultaneously.
•
In RAID 60 configurations, drives are arranged in parity groups. You can replace several drives
simultaneously, if no more than two of the drives being replaced belong to the same parity group.
To remove more drives from an array than the fault tolerance method can support, follow the previous
guidelines for removing several drives simultaneously, and then wait until rebuild is complete (as
indicated by the drive LEDs) before removing additional drives.
However, if fault tolerance has been compromised, and you must replace more drives than the fault
tolerance method can support, delay drive replacement until after you attempt to recover the data (refer to
"Recovering from compromised fault

Automatic data recovery (rebuild)

When you replace a drive in an array, the controller uses the fault-tolerance information on the remaining
drives in the array to reconstruct the missing data (the data that was originally on the replaced drive) and
then write the data to the replacement drive. This process is called automatic data recovery or rebuild. If
fault tolerance is compromised, the controller cannot reconstruct the data, and the data is likely lost
permanently.
If another drive in the array fails while fault tolerance is unavailable during rebuild, a fatal system error can
occur, and all data on the array can be lost. However, failure of another drive does not always lead to a
fatal system error in the following exceptional cases:
•
Failure after activation of a spare drive
•
Failure of a drive that is not mirrored to any other failed drives (in a RAID 10 configuration)
•
Failure of a second drive in a RAID 50 or RAID 60 configuration if the two failed drives are in different
parity groups
•
Failure of a second drive in a RAID 6 configuration
Time required for a rebuild
The time required for a rebuild varies, depending on several factors:
•
The priority that the rebuild is given over normal I/O operations (you can change the priority setting
by using HPE SSA)
•
The amount of I/O activity during the rebuild operation
•
The average bandwidth capability (MBps) of the drives
•
The availability of drive cache
•
The brand, model, and age of the drives
•
The amount of unused capacity on the drives
•
For RAID 5, RAID 50, RAID 6, and RAID 60, the number of drives in the array
•
The strip size of the logical volume
tolerance" on page 23).
Drive procedures 24