Which procedure for backing up a relational database on EC2 that is using a set of RAlDed 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
Explanation:
http://media.amazonwebservices.com/AWS_Storage_Options.pdf (page 11)
D (probably not B as it is incomplete)
http://www.aiotestking.com/amazon/which-the-database-cannot-be-written-to-and-results-in-a-consistent-backup/
I’m picking D because B and D are pretty much the same except B doesn’t start the App/DB which means it doesn’t minimize the down time. This question/answer is debatable..
https://aws.amazon.com/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.
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It says right there in your reference…”or shutting down the associated EC2 instance. After completing the steps to halt all I/O, take a snapshot of each EBS volume.”
I’d go with B
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C. You can freeze the disk run the snapshot and unfreeze the disk without inconsistency.
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B
http://jayendrapatil.com/tag/ebs/
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E
As per http://jayendrapatil.com/tag/ebs/
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