220-1201 Practice Question: A server with a RAID 6 array of six 2 TB drives…

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  The new drives are not the same capacity as the originals.

  Why it's wrong here

  When replacing drives in a RAID array, using drives with a larger capacity than the originals is generally permissible. The RAID controller will typically utilize only the capacity of the smallest drive in the array for all members, effectively underutilizing the larger new drives. While this is inefficient, it does not inherently prevent a RAID 6 rebuild from completing successfully after two drive failures, as the data structure and parity calculations remain consistent within the allocated space.

• ✗

  The RAID controller firmware is outdated.

  Why it's wrong here

  While outdated RAID controller firmware can introduce various performance issues or compatibility problems, it is less probable to be the direct cause of a rebuild failure in a RAID 6 array after two drives have already failed. Firmware issues typically manifest as general instability or inability to recognize new drives, rather than a specific inability to reconstruct data from the remaining healthy drives during a critical rebuild operation. A hardware fault in a remaining drive is a more direct and common cause for such a failure.

• ✓

  A third drive has developed bad sectors.

  Why this is correct

  A RAID 6 array can tolerate the failure of any two drives because it stores two independent parity blocks. However, during a rebuild operation, the RAID controller must read data from all remaining healthy drives to reconstruct the missing data onto the new replacement drives. If a third drive, beyond the initial two that failed, develops unreadable bad sectors, the controller cannot access the necessary data or parity information to complete the reconstruction process, leading to an unrecoverable rebuild failure. This scenario highlights the critical vulnerability during rebuilds.

• ✗

  The rebuild process was interrupted by a power outage.

  Why it's wrong here

  While a power outage would certainly interrupt a RAID rebuild process, most modern RAID controllers are designed to resume a rebuild from where it left off once power is restored, assuming no further hardware damage occurred during the outage. The scenario describes a rebuild failure without mentioning any power events, making a hardware fault within the array, such as a third drive developing issues, a more direct and probable cause for the rebuild's inability to complete.