Fault-Tolerant Configuration for Critical Data on EC2 Instance

Answer - A.

Option A is CORRECT because, as mentioned above, RAID 1 configuration maintains the exact copy of the data (via mirroring) in a backup EBS volume that can be used in case of the failure of the main volume, providing redundancy and fault tolerance.

Option B is incorrect because, although each Amazon EBS volume is automatically replicated within its Availability Zone, it is done so to protect it from any component failure from the AWS side.

It does not withstand any failures at the user level.

It is the user's responsibility to replicate the data that is stored on the EBS volume.

EBS volumes are not automatically backed up to additional hardware in the same availability zone.

You will need to set up your backup strategy when using EBS volumes.

EBS Snapshot Doc: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSSnapshots.html.

Option C is incorrect because RAID 5 does not improve the fault tolerance.

RAID 5 and RAID 6 are not recommended for Amazon EBS because these RAID modes' parity write operations consume some of the IOPS available to your volumes.

Option D is incorrect because RAID 0 configuration helps improve the performance but does not provide redundancy or mirroring of the data across disks.

As a result of having data striped across all disks, any failure will result in total data loss.

More information on RAID Configurations with EBS volumes:

As per the AWS documentation, it is clearly given to use RAID 1 configuration for fault tolerance of EBS volumes.

With Amazon EBS, you can use any of the standard RAID configurations that you can use with a traditional bare metal server, as long as the operating system for your instance supports that particular RAID configuration.

This is because all RAID is accomplished at the software level.

For greater I/O performance than you can achieve with a single volume, RAID 0 can stripe multiple volumes together; for on-instance redundancy, RAID 1 can mirror two volumes together.

For more information on RAID configuration, please visit the below URL-

http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/raid-config.html

Option A is partially correct in that RAID 1 configuration provides fault tolerance by mirroring the data across two EBS volumes. However, it is not the most fault-tolerant option because it only protects against the failure of one EBS volume. If both EBS volumes fail at the same time, the data will be lost.

Option B is incorrect. Although EBS volumes are durable and backed up to additional hardware in the same availability zone, this does not provide fault tolerance in case of a failure of the EBS volume or the EC2 instance itself.

Option C is incorrect because RAID 5 configuration does not provide fault tolerance on EBS volumes. RAID 5 is a striping method that provides improved I/O performance by distributing data across multiple EBS volumes. It does offer some protection against the failure of one EBS volume, but not against the failure of multiple EBS volumes.

Option D is incorrect because RAID 0 does not provide any fault tolerance. It is a striping method that combines multiple EBS volumes into one logical volume, providing improved I/O performance but no protection against failure.

The most fault-tolerant configuration for critical data stored in EBS volumes would be to use a combination of RAID 1 mirroring and a multi-Availability Zone (multi-AZ) deployment. Multi-AZ deployment involves running the application and storing the data on EBS volumes in multiple availability zones. In case of a failure in one availability zone, the application can automatically switch to the EBS volumes in another availability zone, ensuring continuous availability of the application and data.