AWS Certified Developer - Associate Questions and Answers (Dumps and Practice Questions)

Question : To host a Apache WebServer for the www.HadoopExam.com website you launched an EBS backed Linux instance.
How can a you detach the root device and attach it to another instance as a secondary volume?

1. It is not possible to mount the root device as a secondary volume on the other instance
2. It is not possible to mount the root volume to some other instance
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4. Unmount the root volume first and then detach it

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Explanation: You can detach an Amazon EBS volume from an instance explicitly or by terminating the instance. However, if the instance that the volume is attached to is running, you must unmount the volume (from the instance) before you detach it. Failure to do so results in the volume being stuck in the busy state while it is trying to detach, which could possibly damage the file system or the data it contains. If an EBS volume is the root device of an instance, you must stop the instance before you can detach the volume. When a volume with an AWS Marketplace product code is detached from an instance, the product code is no longer associated with the instance.

Important : After you detach a volume, you are still charged for volume storage as long as the storage amount exceeds the limit of the Free Usage Tier. You must delete a volume to avoid incurring further charges. For more information, see Deleting an Amazon EBS Volume.This example unmounts the volume and then explicitly detaches it from the instance. This is useful when you want to terminate an instance or attach a volume to a different instance. To verify that the volume is no longer attached to the instance, see Viewing Volume Information
Note that you can reattach a volume that you detached (without unmounting it), but it might not get the same mount point and the data on the volume might be out of sync if there were writes to the volume in progress when it was detached.
To detach an EBS volume using the console
First, use the following command to unmount the /dev/sdh device.
[ec2-user ~]$ umount -d /dev/sdh
Open the Amazon EC2 console.
Click Volumes in the navigation pane.
Select a volume and then click Detach Volume.
In the confirmation dialog box, click Yes, Detach.

To detach an EBS volume from an instance using the command line
You can use one of the following commands. For more information about these command line interfaces, see Accessing Amazon EC2.
detach-volume (AWS CLI)
ec2-detach-volume (Amazon EC2 CLI)
Dismount-EC2Volume (AWS Tools for Windows PowerShell)
Troubleshooting : If your volume stays in the detaching state, you can force the detachment by clicking Force Detach. Forcing the detachment can lead to data loss or a corrupted file system. Use this option only as a last resort to detach a volume from a failed instance, or if you are detaching a volume with the intention of deleting it. The instance doesn't get an opportunity to flush file system caches or file system metadata. If you use this option, you must perform file system check and repair procedures.

If you've tried to force the volume to detach multiple times over several minutes and it stays in the detaching state, you can post a request for help to the Amazon EC2 forum. To help expedite a resolution, include the volume ID and describe the steps that you've already taken.If an Amazon EBS volume is the root device of an instance, it cannot be detached unless the instance is in the stopped state.

Question : You have created an EBS instance in the US-East-a AZ which had a volume of GB in the US-East-b zone. How can you attach the volume to an instance?

1. Take a snapshot of the volume. Create a new volume in the USEast-1a and attach that to the instance
2. Since both the volume and the instance are in the same region, the user can attach the volume
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4. Use the volume replicate function to create a new volume in the US-East-1a and attach that to the volume

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Explanation: If an EBS volume is not in the same AZ of an EC2 instance, it cannot be attached to the instance. The only option is to take a snapshot of the volume and create a new volume in the instance's AZ. You can back up the data on your EBS volumes to Amazon S3 by taking point-in-time snapshots. Snapshots are incremental backups, which means that only the blocks on the device that have changed after your most recent snapshot are saved. When you delete a snapshot, only the data exclusive to that snapshot is removed. Active snapshots contain all of the information needed to restore your data (from the time the snapshot was taken) to a new EBS volume.

If you are dealing with snapshots of sensitive data, you should consider encrypting your data manually before taking the snapshot or storing the data on a volume that is enabled with Amazon EBS encryption. For more information, see Amazon EBS Encryption.
Snapshot Overview : When you create an EBS volume, you can create it based on an existing snapshot. The new volume begins as an exact replica of the original volume that was used to create the snapshot. When you create a volume from an existing snapshot, it loads lazily in the background so that you can begin using them right away. If you access a piece of data that hasn't been loaded yet, the volume immediately downloads the requested data from Amazon S3, and then continues loading the rest of the volume's data in the background. For more information, see Creating an Amazon EBS Snapshot.

Snapshots of encrypted volumes are automatically encrypted. Volumes that are created from encrypted snapshots are also automatically encrypted. Your encrypted volumes and any associated snapshots always remain protected. For more information, see Amazon EBS Encryption.

You can share your unencrypted snapshots with specific AWS accounts, make them public to share them with the entire AWS community. User with access to your snapshots can create their own EBS volumes from your snapshot. This doesn't affect your snapshot. For more information about how to share snapshots, see Sharing an Amazon EBS Snapshot. Note that you can't share encrypted snapshots, because your volume encryption keys and master key are specific to your account. If you need to your encrypted snapshot data, you can migrate the data to an unencrypted volume and then share a snapshot of that volume. For more information, see Migrating Data.

Snapshots are constrained to the region in which they are created. After you have created a snapshot of an EBS volume, you can use it to create new volumes in the same region. For more information, see Restoring an Amazon EBS Volume from a Snapshot. You can also copy snapshots across regions, making it easier to leverage multiple regions for geographical expansion, data center migration and disaster recovery. You can copy any accessible snapshots that are in the available state. For more information, see Copying an Amazon EBS Snapshot.

Question : You are creating an EBS volume and asks for your advice to your senior developer Tom. Which below advice Tom should you not give to you for creating an EBS volume?

1. Attach multiple volumes to the same instance
2. Take the snapshot of the volume when the instance is stopped
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4. Stripe multiple volumes attached to the same instance

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Explanation: When a user creates an EBS volume, the user can attach it to a running instance. The user can attach multiple volumes to the same instance and stripe them together to increase the I/O. The user can take a snapshot from the existing volume but cannot create an AMI from the volume. However, the user can create an AMI from a snapshot. Benefits of Using EBS Volumes :
Data Availability : When you create an EBS volume in an Availability Zone, it is automatically replicated within that zone to prevent data loss due to failure of any single hardware component. After you create a volume, you can attach it to any EC2 instance in the same Availability Zone. After you attach a volume, it appears as a native block device similar to a hard drive or other physical device. At that point, the instance can interact with the volume just as it would with a local drive; the instance can format the EBS volume with a file system, such as ext3, and then install applications. An EBS volume can be attached to only one instance at a time within the same Availability Zone. However, multiple volumes can be attached to a single instance. If you attach multiple volumes to a device that you have named, you can stripe data across the volumes for increased I/O and throughput performance.

You can get monitoring data for your EBS volumes at no additional charge (this includes data for the root device volumes for EBS-backed instances). For more information, see Monitoring Volumes with CloudWatch.
Data Persistence : An EBS volume is off-instance storage that can persist independently from the life of an instance. You continue to pay for the volume usage as long as the data persists. By default, EBS volumes that are attached to a running instance automatically detach from the instance with their data intact when that instance is terminated. The volume can then be reattached to a new instance, enabling quick recovery. If you are using an EBS-backed instance, you can stop and restart that instance without affecting the data stored in the attached volume. The volume remains attached throughout the stop-start cycle. This enables you to process and store the data on your volume indefinitely, only using the processing and storage resources when required. The data persists on the volume until the volume is deleted explicitly. After a volume is deleted, it can't be attached to any instance. The physical block storage used by deleted EBS volumes is overwritten with zeroes before it is allocated to another account. If you are dealing with sensitive data, you should consider encrypting your data manually or storing the data on a volume that is enabled with Amazon EBS encryption.By default, EBS volumes that are created and attached to an instance at launch are deleted when that instance is terminated. You can modify this behavior by changing the value of the flag DeleteOnTermination to false when you launch the instance. This modified value causes the volume to persist even after the instance is terminated, and enables you to attach the volume to another instance.
Data Encryption : For simplified data encryption, you can create encrypted EBS volumes with the Amazon EBS encryption feature. You can use encrypted EBS volumes to meet a wide range of data-at-rest encryption requirements for regulated/audited data and applications. Amazon EBS encryption uses 256-bit Advanced Encryption Standard algorithms (AES-256) and an Amazon-managed key infrastructure. The encryption occurs on the server that hosts the EC2 instance, providing encryption of data-in-transit from the EC2 instance to EBS storage. For more information, see Amazon EBS Encryption.
Amazon EBS encryption uses AWS Key Management Service (AWS KMS) master keys when creating encrypted volumes and any snapshots created from your encrypted volumes. The first time you create an encrypted EBS volume in a region, a default master key is created for you automatically. This key is used for Amazon EBS encryption unless you select a Customer Master Key (CMK) that you created separately using the AWS Key Management Service. Creating your own CMK gives you more flexibility, including the ability to create, rotate, disable, define access controls, and audit the encryption keys used to protect your data. For more information, see the AWS Key Management Service Developer Guide.

Snapshots : Amazon EBS provides the ability to create snapshots (backups) of any EBS volume and write a copy of the data in the volume to Amazon S3, where it is stored redundantly in multiple Availability Zones. The volume does not need be attached to a running instance in order to take a snapshot. As you continue to write data to a volume, you can periodically create a snapshot of the volume to use as a baseline for new volumes. These snapshots can be used to create multiple new EBS volumes, expand the size of a volume, or move volumes across Availability Zones. Snapshots of encrypted EBS volumes are automatically encrypted.
When you create a new volume from a snapshot, it's an exact copy of the original volume at the time the snapshot was taken. EBS volumes that are restored from encrypted snapshots are automatically encrypted. By optionally specifying a different volume size or a different Availability Zone, you can use this functionality to increase the size of an existing volume or to create duplicate volumes in new Availability Zones. The snapshots can be shared with specific AWS accounts or made public. When you create snapshots, you incur charges in Amazon S3 based on the volume's total size. For a successive snapshot of the volume, you are only charged for any additional data beyond the volume's original size.
Snapshots are incremental backups, meaning that only the blocks on the volume that have changed after your most recent snapshot are saved. If you have a volume with 100 GiB of data, but only 5 GiB of data have changed since your last snapshot, only the 5 GiB of modified data is written to Amazon S3. Even though snapshots are saved incrementally, the snapshot deletion process is designed so that you need to retain only the most recent snapshot in order to restore the volume. When a user creates an EBS volume, the user can attach it to a running instance. The user can attach multiple volumes to the same instance and stripe them together to increase the I/O. The user can take a snapshot from the existing volume but cannot create an AMI from the volume. However, the user can create an AMI from a snapshot.

AWS Certified Developer - Associate Questions and Answers (Dumps and Practice Questions)

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