When a drive fails in a Dynamic Disk Pool (DDP) with no free capacity, what happens to the data?

Dynamic Disk Pools (DDPs) in NetApp E-Series systems are designed with integrated spare capacity, known as "preservation capacity." This capacity is reserved specifically for data reconstruction in the event of a drive failure. When a drive fails, the SANtricity controller uses the distributed parity data across the remaining healthy drives to rebuild the data segments from the failed drive. This rebuilt data is then written into the reserved preservation capacity, which is spread across all other drives in the pool. This process is independent of the "free capacity" available for creating new volumes and does not require a dedicated hot spare drive.

A. Data is reconstructed using distributed parity information inherent to the DDP's data layout, not from a separate on-board backup database.

C. "Rebuilt" is the correct term for reconstructing data from a failed drive using parity. "Evacuated" implies copying data from a failing, but still operational, drive.

D. DDPs fundamentally replace the concept of dedicated hot spare drives with integrated, distributed preservation capacity for rebuilds.

1. NetApp Technical Report TR-4090: Dynamic Disk Pools on NetApp E-Series.

Page 6

Section "DDP Preservation Capacity": "Preservation capacity is spare capacity that is reserved for reconstructing data from a failed drive. The amount of preservation capacity is determined by the number of drives in the DDP."

Page 7

Section "DDP Rebuild": "When a drive fails

the DDP rebuilds the data that was on the failed drive into the preservation capacity. The rebuild process uses the parity data that is distributed across the other drives in the pool to reconstruct the data."

2. NetApp E-Series SANtricity 11.7 System Manager Documentation.

Section: "About dynamic disk pools": "When a drive fails

the controller automatically reconstructs the data that was on the failed drive to the reserved preservation capacity within the pool. This feature is a key advantage over traditional volume groups

which require a hot spare drive for reconstruction."