Data Recovery (Rebuild); Time Required For A Rebuild - HP Smart Array B140i User Manual

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Use replacement drives that have a capacity equal to or greater than the smallest drive in the array.
The controller immediately fails drives that have insufficient capacity.
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After removing a drive, wait 3 seconds. After 3 seconds, the firmware generates an event indicating
that the drive has been removed. You can now safely install a new drive.
To replace more drives in an array than the fault tolerance method can support, follow the previous
guidelines for replacing several drives simultaneously. Wait until rebuild is complete, as indicated by HPE
SSA, before replacing additional drives.
If you need to replace more drives than the fault tolerance method can support because fault tolerance
has been compromised, back up the data before replacing any drives. For more information, see
"Recovering from compromised fault tolerance (on page 17)."

Data recovery (rebuild)

When you replace a hard drive in an array, the controller uses the fault-tolerance information on the
remaining drives in the array to reconstruct the data from the original drive and write it to the replacement
drive. This process is called automatic data recovery or rebuild. If fault tolerance is compromised, this
data cannot be reconstructed and, likely, is lost permanently.
Rebuilding an array requires that you either be in offline HPE SSA or booted into the operating system
with the driver installed.
The operating system must be running for the rebuild to occur.
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 is then lost. In exceptional cases, however, failure of another drive does
not always cause a fatal system error. These exceptions include the following:
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Failure after activation of a spare drive
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Failure of a drive that is not mirrored to any other failed drives (in a RAID 1+0 configuration)

Time required for a rebuild

The time required for a rebuild varies, depending on several factors:
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The priority that the rebuild is given over normal I/O operations
Change the priority setting with HPE SSA
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The amount of I/O activity during the rebuild operation
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The rotational speed of the hard drives
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The brand, model, and age of the drives
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The amount of unused capacity on the drives
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In RAID 5 configurations, the time required for a rebuild may be affected by data parity initialization.
Allow approximately 15 minutes per gigabyte for the rebuild process to complete.
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.
When automatic data recovery has finished, the state of the logical volume is updated in HPE
SSA/SSA-CLI/agents, and an event is posted to the system event log indicating that the rebuild is
complete.
If HPE SSA or the posted event indicates that the rebuild has terminated abnormally, determine the
appropriate course of action. See "Abnormal termination of a rebuild (on page 19)."
("HPE Smart Storage Administrator" on page 23).
Replacing, moving, or adding hard drives 18