ETERNUS disk storage systems data are protected via a disk drive patrol function. An internal controller regularly checks the disk drives, in background, to detect errors and write failures. This process also ensures that data consistency within the volume group(*Note) is also maintained.

The data on each disk drive is read, and if an error is detected, data is reconstructed using redundant information contained within the volume group. The corrected data is then written to a new valid area on the disk drive.

*Note : The volume group is all the disks in a RAID configuration.

• Higher data reliability as data errors are quickly found and corrected (by reconstruction) and disk write failures are avoided.