Which procedure for backing up a relational database on EC2 that is using a set of RAIDed EBS volumes for storage minimizes the time during which the database cannot be written to and results in a consistent backup?
A. 1. Detach EBS volumes, 2. Start EBS snapshot of volumes, 3. Re-attach EBS volumes
B. 1. Stop the EC2 Instance. 2. Snapshot the EBS volumes
C. 1. Suspend disk I/O, 2. Create an image of the EC2 Instance, 3. Resume disk I/O
D. 1. Suspend disk I/O, 2. Start EBS snapshot of volumes, 3. Resume disk I/O
E. 1. Suspend disk I/O, 2. Start EBS snapshot of volumes, 3. Wait for snapshots to complete, 4. Resume disk I/O
Correct Answer: B
Explanation/Reference:
https://aws.amazon.com/cn/premiumsupport/knowledge-center/snapshot-ebs-raid-array/ To create an "application-consistent" snapshot of your RAID array, stop applications from writing to the RAID array, and flush all caches to disk. Then ensure that the associated EC2 instance is no longer writing to the RAID array by taking steps such as freezing the file system, unmounting the RAID array, or ‘shutting down the associated EC2 instance*. After completing the steps to halt all I/O, take a snapshot of each EBS volume. http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs- detaching-volume.html You can detach an Amazon EBS volume from an instance explicitly or by terminating the instance. However, if the instance is running, you must first unmount the volume from the instance."
For me is A
key word “minimizes the time” B is valid but stopping and starting the instance require more time and how you “Suspend disk I/O” for a live instance
This is obsolete.
No need to stop the instance before snapshot now.
https://aws.amazon.com/premiumsupport/knowledge-center/snapshot-ebs-raid-array/?nc1=h_ls
Wrong. It’s E
To create an “application-consistent” snapshot of your RAID array, stop applications from writing to the RAID array, and flush all caches to disk. Then ensure that the associated EC2 instance is no longer writing to the RAID array by taking steps such as freezing the file system, unmounting the RAID array, or shutting down the associated EC2 instance. After completing the steps to halt all I/O, take a snapshot of each EBS volume.
https://aws.amazon.com/premiumsupport/knowledge-center/snapshot-ebs-raid-array/
a consistent backup for a relational database on EC2, should be B
E is definetly wrong.
As said at this link https://aws.amazon.com/premiumsupport/knowledge-center/snapshot-ebs-raid-array/
we need to stop IO (even with a shutdown but is not mandatory):
Resolution
To be sure the EBS snapshot for your RAID array can be used to restore the array, follow these steps:
Stop all applications from writing to the RAID array.
Flush all caches to the disk.
Confirm that the associated EC2 instance is no longer writing to the RAID array by taking actions such as freezing the file system, unmounting the RAID array, or even shutting down the EC2 instance.
After taking steps to halt all disk-related activity to the RAID array, take a snapshot of each EBS volume in the array.
B is correct , pls refer to link https://aws.amazon.com/premiumsupport/knowledge-center/snapshot-ebs-raid-array/
answer is D, there is no need to wait for the snapshot:
Snapshots occur asynchronously; the point-in-time snapshot is created immediately, but the status of the snapshot is pending until the snapshot is complete (when all of the modified blocks have been transferred to Amazon S3), which can take several hours for large initial snapshots or subsequent snapshots where many blocks have changed. While it is completing, an in-progress snapshot is not affected by ongoing reads and writes to the volume.
Correct answer is D.
sorry .. D is wrong
correct answer is E
E. 1. Suspend disk I/O, 2. Start EBS snapshot of volumes, 3. Wait for snapshots to complete, 4. Resume disk I/O