Example: Writing data to a disk unit when its corresponding parity data is on a failed disk unit

The write request from the iSeries™ server detects a disk failure for the disk unit that contains the corresponding parity data. The write request is to sector 2 on disk unit 4. Parity information for disk unit 4, sector 2, is on failed disk unit 3. The following actions occur:

  1. A failure is detected on the disk unit that contains the parity data, disk unit 3.
  2. Calculating parity information is not required because it cannot write to parity sector 2 of disk unit 3. Therefore, there is no requirement to read the original data and the parity information.
  3. Data is written to disk unit 4, sector 2.

    A write operation requires only one write operation for the new data. Parity data for parity sector 2 on disk unit 3 will be rebuilt during synchronization after disk unit 3 is replaced.

Parent topic: Write operations on a failed disk unit