HP NetRAID 1Si Controller - Manual (Page 105)

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5 Reconstructing and Rebuilding
Drives
Reconstructing and rebuilding are two important features of HP NetRAID
systems. It is important to know the difference between these two terms.
•
Reconstructing is the process of reorganizing data when you make a
fundamental change to your system such as changing RAID levels. See
"Reconstructing Data" in this chapter for more information.
•
Rebuilding is the process of recreating data on a replacement drive after a
drive failure. See "Rebuilding Data" in this chapter for more information.
Reconstructing Data
Reconstruction is the process of reorganizing data to correspond with a change in
the HP NetRAID system. The following changes require reconstructing your data:
•
Adding a physical drive to an existing logical drive.
•
Removing a physical drive from an existing logical drive.
•
Changing a logical drive from one RAID level to another.
NOTE Reconstruction can be done only on arrays containing just one
logical drive each. HP NetRAID cannot reconstruct an array
using array spanning or arrays containing multiple logical
drives.
Reconstruction occurs in the background, so the HP NetServer and the affected
drives remain available throughout the reconstruction process.
The reconstruction rate is about 80 to 180 MB per minute (depending on drive
performance, system loading, and whether or not you have enabled the Power Fail
Safeguard parameter). Count the capacity to be reconstructed as the number of
physical drives participating in the reconstruction multiplied by drive capacity.
Power Fail Safeguard Feature
The Power Fail Safeguard feature (PFS) allows users to protect a disk array during
the reconstruction process should a power failure occur. When you use this
feature, a copy of the data currently being reorganized always remains on disk, so