TOP 50 Interview Questions on AWS Cloud Computing Services -Elastic Block Storage (EBS)

1. What kind of performance can I expect from Amazon EBS volumes?

It provides four current generation volume types: General Purpose SSD (gp2), Provisioned IOPS SSD (io1), Throughput Cold HDD (sc1) and Optimized HDD (st1). These volume types differ in performance characteristics and price, allowing you to tailor your storage performance and price to the requirements of your applications. The average latency between EBS and EC2 instances is single digit milliseconds.

2. When an Amazon EC2 instance terminates what happens to my data?

Unlike the info stored on an area instance store (which persists only as long as that instance is alive), data stored on an Amazon EBS volume can persist independently of the life of the instance. Therefore, we recommend that you simply use the local instance store just for temporary data. For data requiring a better level of durability, we recommend using Amazon EBS volumes or backing up the info to Amazon S3. If you’re using an Amazon EBS volume as a root partition, set the Delete on termination flag to “No” if you would like your Amazon EBS volume to persist outside the life of the instance.

3. When would I use Fast Snapshot Restore (FSR)?

You should enable FSR on snapshots if you are concerned about latency of data access when you restore data from a snapshot to a volume and want to avoid the initial performance hit during initialization. FSR is meant to assist with use cases like backup & restore, test/dev volume copies, virtual desktop infrastructure (VDI), and booting from custom AMIs. By enabling FSR on your snapshot, you will see improved and predictable performance whenever you need to restore data from that snapshot.

4. Does enabling FSR for my snapshot speed up snapshot creation?

No. From your snapshot ‘our volumes  FSR-enabled snapshots improve restoring backup data. FSR-enabled snapshots don’t speed up snapshot creation time.

5. How do I enable Fast Snapshot Restore (FSR)?

To use the feature, invoke the new enable-fast-snapshot-restores API on a snapshot within the supply zone (AZ) where initialized volumes are to be restored.

The FSR-enabled snapshot could also be in anybody of the subsequent states: enabling, optimizing, enabled, disabling, disabled. State transitions are published as CloudWatch events and the FSR state can be checked via the describe-fast-snapshot-restores API.

Enabling FSR on a snapshot doesn’t change any existing snapshot API interactions, and existing workflows won’t get to change. FSR are often enabled or disabled on account-owned snapshots only. FSR cannot be applied to shared snapshots. You can view the list of your FSR-enabled snapshots via API or the console.

6. How do I use Fast Snapshot Restore (FSR)?

FSR-enabled snapshots are fully initialized to create volumes. However, there are limits on the amount of volumes which will be created with immediate full performance. These limits are expressed within the sort of a credit bucket that’s related to an FSR-enabled snapshot during a given AZ. The important things to know regarding credits:

1. one volume create operation consumes one credit

2. the amount of credits may be a function of the FSR-enabled snapshot size

3. Credits refill over time

4. Maximum credit bucket size is 10

It’s important to note that the credit bucket size is a function of the FSR-enabled snapshot size, not the size of the volumes that are created. For example, it’s possible to make up to 10 1TiB volumes from a 100GiB snapshot directly .

Lastly, each AZ during which the snapshot is FSR-enabled gets its own credit bucket independent of other AZs.

7. How do I know when a volume was created from an FSR-enabled snapshot?

When using FSR, a replacement EBS-specific attribute (fastRestored) is added within the DescribeVolumes API to denote the status at create time. When a volume is created from an FSR-enabled snapshot without sufficient volume-create credits, the create will succeed but the volume will not be initialized.

8. Which volume should I choose?

Amazon EBS includes two major storage categories: SSD-backed storage for transactional workloads and HDD-backed storage for throughput workloads. SSD-backed volumes are designed for IOPS-intensive database workloads, boot volumes, transactional, and workloads that need high IOPS. SSD-backed volumes include Provisioned IOPS SSD and General Purpose SSD. HDD-backed volumes are designed for throughput-intensive and  large I/O sizes, big-data workloads, and sequential I/O patterns. HDD-backed volumes include Throughput Optimized HDD and Cold HDD.

9. Are EBS Standard Volumes still available?

EBS Standard Volumes are renamed to EBS Magnetic volumes. Any existing volumes won’t be changed as a result of this and there are not any functional differences within the EBS Magnetic offering compared to EBS Standard. The name of this offering was changed to avoid confusion with our General Purpose SSD volume type which is our recommended default volume type.

10. How do I modify the capacity, performance, or type of an existing EBS volume?

Changing a volume configuration is easy. The Elastic Volumes feature allows you to extend capacity, tune performance, or change your volume type with one CLI call, API call or a couple of console clicks.

11. Do volumes need to be un-mounted to take a snapshot?

No, snapshots are often wiped out real time while the quantity is attached and in use. Which could exclude any data that has been locally cached by your application, Snapshots only capture data that has been written to your Amazon EBS volume. We recommend detaching the quantity cleanly, issuing the snapshot command, then reattaching the quantity, To ensure consistent snapshots on volumes attached to an instance. For Amazon EBS volumes that function root devices, we recommend shutting down the machine to require a clean snapshot.

12. Does it take longer to snapshot an entire 16 TB volume as compared to an entire 1 TB volume?

By design, an EBS Snapshot of a whole 16 TB volume should take not more than the time it takes to snapshot a whole 1 TB volume. However, the particular time taken to make a snapshot depends on several factors including the quantity of knowledge that has changed since the last snapshot of the EBS volume.

13. Are snapshots versioned? Can I read an older snapshot to try to do a point-in-time recovery?

Each snapshot is given a singular identifier, and customers can create volumes supporting any of their existing snapshots.

14. How can I discover Amazon EBS snapshots that are shared with me?

You can find snapshots that are shared with you by selecting Private Snapshots from the list within the Snapshots section of the AWS Management Console. This section lists both snapshots that you simply own and snapshots that are shared with you.

15. How can I find which Amazon EBS snapshots are shared globally?

You can find snapshots that are shared globally by selecting Public Snapshots from the list within the Snapshots section of the AWS Management Console.

16. Are Provisioned IOPS SSD (io1) volumes available for all Amazon EC2 instance types?

Yes, Provisioned IOPS SSD volumes are available for Amazon EC2 Instance Types. To enable your EC2 instances to use the IOPS provisioned on an EBS volume consistently and predictably, you’ll launch selected EC2 instance types as EBS-optimized instances. With options between 62.5 MB/s and a couple of ,375 MB/s counting on the instance type used, EBS-optimized instances deliver dedicated throughput between Amazon EC2 and Amazon EBS. To achieve optimum performance for workloads requiring quite 32,000 IOPS or 500 MB/s, you ought to use EC2 instances that support the Nitro system.

17. What level of performance consistency can I expect to see from my Provisioned IOPS SSD (io1) volumes?

When attached to EBS-optimized instances, Provisioned IOPS SSD (io1) volumes are designed to deliver within 10% of the provisioned IOPS performance 99.9% of the time during a given year. Exact performance depends on the application’s I/O requirements.

18. What level of performance latency can I expect to see from my Provisioned IOPS SSD (io1) volumes?

When attached to EBS-optimized instances, Provisioned IOPS volumes are able to do single digit millisecond latencies. Exact performance depends on the application’s I/O requirements.

19. Does the I/O size of my application reads and writes affect the rate of IOPS I get from my Provisioned IOPS SSD (io1) volumes?

Yes. The IOPS rate you get depends on the I/O size of your application reads and writes, For a given allocation of resources, .

The base I/O size of Provisioned IOPS volumes is 16KB. Volumes up to 500 MB/s throughput, up to 32,000 IOPS have an enhanced throughput I/O size of 256KB. Every increase in I/O size above the bottom size (16KB) or enhanced throughput size (256KB) linearly increases the resources you would like to realize an equivalent IOPS rate.

20. What level of performance consistency am i able to expect to ascertain from my HDD-backed volumes?

Throughput Optimized Cold HDD and HDD volumes are designed to deliver within 10% of the expected throughput performance 99% of the time in a given year, When attached to EBS-optimized instances. Your exact performance depends on your application’s I/O requirements and therefore the performance of your EC2 instance.

21. How can I use EBS direct APIs for Snapshots?

This feature is often used via the subsequent APIs which will be called using AWS CLI or via AWS SDK.

List Snapshot Blocks: The ListSnapshotBlocks API operation returns the block indexes and block tokens for blocks within the specified snapshot.

List Changed Blocks: The ListChangedBlocks API operation returns the block indexes and block tokens for blocks that are different between two specified snapshots of an equivalent volume/snapshot lineage.

Get Snapshot Blocks: The GetSnapshotBlock API operation returns the info during a block for the required snapshot ID, block index, and block token.

22. What block sizes are supported by getSnapshotBlock API?

GetSnapshotBlock will return data as 512KiB blocks.

23. What is Amazon EBS encryption?

Amazon EBS encryption offers seamless encryption of EBS data volumes, boot volumes and snapshots, eliminating the necessity to create and maintain a secure key management infrastructure. It enables data at keys you create and manage using the AWS Key Management Service (KMS), or rest security by encrypting your data using Amazon-managed keys. The encryption occurs on the servers that host EC2 instances, providing encryption of knowledge because it moves between EC2 instances and EBS storage. For more details, see Amazon EBS encryption within the Amazon EC2 User Guide.

24. What is the AWS Key Management Service (KMS)?

AWS KMS is a managed service that makes it easy for you to create and control the encryption keys used to encrypt your data. AWS Key Management Service is integrated with other AWS services including Amazon EBS, Amazon S3, and Amazon Redshift, to make it simple to encrypt your data with encryption keys that you manage. AWS Key Management Service is also integrated with AWS CloudTrail to provide you with logs of all key usage to help meet your regulatory and compliance needs. To learn more about KMS, visit the AWS Key Management Service product page.

25. Why should I use EBS encryption?

You can use Amazon EBS encryption to satisfy security and encryption compliance requirements for data at rest encryption within the cloud. Pairing encryption along with existing IAM access control policies improves a company’s defense-in-depth strategy.

26. How are my Amazon EBS encryption keys managed?

Amazon EBS encryption handles key management for you. Each newly created volume gets a singular 256-bit AES key; Volumes created from the encrypted snapshots share the key. Which implements strong logical and physical security controls to stop unauthorized access, These keys are protected by our own key management infrastructure. Associated keys and data are encrypted using the industry-standard AES-256 algorithm.

27. Does EBS encryption support boot volumes?

Yes, EBS encryption support boot volumes

28. Can I create an encrypted data volume at the time of instance launch?

Yes, using customer master keys (CMKs) that are either AWS-managed or customer-managed. You can specify the volume details and encryption through a RunInstances API call with the BlockDeviceMapping parameter or through the Launch Wizard in the EC2 Console.

29. The storage volume that AWS EBS offers?

The AWS EBS offers the subsequent storage volume options:

General Purpose SSD (gp2): An optimum balance between performance and cost  for a spread of IT workloads. Use cases include virtual desktops, apps, dev and test environments, among others.

Provisioned IOPS SSD (io1): Suitable use cases include large databases and business apps that need 16,000 IOPS or 250 MiB/s of throughput per volume.

Throughput Optimized HDD (st1): a coffee cost alternative for giant storage volume workloads with high performance throughput requirements. Examples include streaming workloads, big data applications, log processing and data warehousing.

Cold HDD (sc1): a cheap alternative to be used cases with a requirement to take care of minimal cost for giant volume data storage. Examples include workloads that are accessed less frequently.

30. Features of the AWS EBS?

Other notable features of the AWS EBS include:

Amazon EBS and NVMe: AWS offers Non-Volatile Memory Express (NVMe) devices for its Nitro-based instance types designed for top performance computing. The Nitro hypervisor system reduces virtualization overhead and offers an equivalent high performance as bare metal hardware.

Amazon EBS Volume Performance: Users get to configure and tune the systems to maximise performance on Linux instances, Since the AWS EBS is delivered as a raw storage solution. AWS offers a detailed guideline on producing optimal configurations for real-world workloads and benchmarking for a variety of I/O characteristics, EC2 instances and EBS volumes.

Amazon EBS Encryption: It supports all EBS volume types to secure data at rest, in transition, snapshots and instances. AWS promises minimal impact on the performance on the storage volume thanks to encryption. Users can manage policies, security, control of snapshots and volume data using the IAM and AWS Key Management Service (AWS KMS).

EBS CloudWatch Events: Users can set policies and automatic actions in response to EBS event notifications. These actions may include operational changes to the activating AWS Lambda functions, environment, batch jobs, and adjusting EBS capacity

31. What are the offers for EBS Optimized Instances?

It offers bursts of performance improvements for storage workloads that need short and intense periods of high device I/O operations. The throughput performance for EBS-optimized instances can vary between 4250 to 14,000 Mbps supported the instance type. For instance, the SSD GP2 volume option is designed to operate within 10 percent of its baseline and burst performance, for 99 percent of the time that it’s used as such. This capability allows low spec instances to replicate the high performance of larger instances for a limited period of the day. As a result, the EBS volumes are optimized for a spread of storage use cases and therefore the demand spikes don’t impact end-user or customer experience. The EBS solutions are optimized by default or available on a coffee hourly pricing.

32. Can I stripe multiple volumes together to get better performance?

Yes. You can stripe multiple volumes together to achieve up to 80,000 IOPS or 2,375 MiB/s when attached to larger EC2 instances. However, performance for st1 and sc1 scales linearly with volume size so there might not be the maximum amount of a benefit to stripe these volumes together.

33. Does the I/O size of my application reads and writes affect the rate of throughput I get from my HDD-backed volumes?

Yes.  In I/O sizes of 1MB HDD-backed volumes the process reads and writes. Sequential I/Os are merged and processed as 1 MB units while each non-sequential I/O is processed as 1MB albeit the particular I/O size is smaller. while a transactional workload with random IOs, like a database, small, won’t perform well on HDD-backed volumes, sequential I/Os and enormous I/O sizes will achieve the advertised performance of st1 and sc1 for a longer period of time.

34. Will I be able to access my snapshots using the regular Amazon S3 API?

No, Through the Amazon EC2 API snapshots are only available .

35. How many concurrent volumes can I create and what happens when I surpass this limit?

The size of the create credit bucket represents the utmost number and therefore the balance of the credit bucket represents the amount of creates available. When filled, up to 10 initialized volumes are often created from an FSR-enabled snapshot directly . Both the utmost size of the credit bucket and therefore the credit bucket balance are published as CloudWatch metrics. Volume creations beyond the limit will proceed as if FSR isn’t enabled on the snapshot.

36. Can I create additional encrypted data volumes at the time of instance launch that are not part of the AMI?

Yes, you can create encrypted data volume with either default or custom CMK encryption at the time of instance launch. You can specify the quantity details and encryption through BlockDeviceMapping object in RunInstances API call or through Launch Wizard in EC2 Console.

37. Can I launch an encrypted EBS instance from an unencrypted AMI?

Yes.

38. Can I share encrypted snapshots and AMIs with other accounts?

Yes. you’ll share encrypted snapshots and AMIs employing a customer-managed customer passkey (CMK) with other AWS accounts.

39. Can I ensure that all new volumes created are always encrypted?

Yes, you’ll enable EBS encryption by default with one setting per region. This ensures that each one new volume is always encrypted.

40. Is there an additional fee to enable Multi-Attach?

No. Multi-Attach are often enabled on an EBS Provisioned IOPS io1 volume and there’ll be charges for the storage (GB-Mo) and IOPS (IOPS-Mo) provisioned.

41. Can I boot an EC2 instance using a Multi-Attach enabled volume?

No.

42. What happens if all of my attached instances do not have the ‘deleteOnTermination’ flag set?

The volume’s deleteOnTermination behavior is determined by the configuration of the last attached instance that is terminated. To ensure predictable delete on termination behavior, enable or disable ‘deleteOnTermination’ for all of the instances to which the quantity is attached.

If you want the volume to be deleted when the attached instances are terminated, enable ‘deleteOnTermination’ for all of the instances to which the volume is attached. If you would like to retain the quantity after the attached instances are terminated, disable ‘deleteOnTermination’ for all attached instances. For more information, see Multi-Attach technical documentation.

43 Can my application use Multi-Attach?

If your application does not require storage layer coordination of write operations, such as a read-only application or it enforces application level IO fencing, then your application can use Multi-Attach.

44. What is EBS Volume Deletion?

EBS volume deletion would wipe out its data and therefore the volume can’t be attached to any instance. However, it are often protected before deletion using EBS snapshots

45. How to create EBS Volume?

EBS volume can be created either

Creating New volumes

• Completely new from console or command line tools and can then be attached to an EC2 instance in the same Availability Zone

Restore volume from Snapshots

• EBS volumes also can be restored from a previously created snapshots
• New volumes created from existing EBS snapshots load lazily within the background.
• There is no need to await all of the info to transfer from S3 to the EBS volume before the attached instance can start accessing the quantity and every one its data.
• If the instance accesses the data that hasn’t yet been loaded, the volume immediately downloads the requested data from S3, and continues loading the rest of the data in the background.

By default EBS volumes are often created and attached to a running EC2 instance by specifying a block device mapping

46. How to detach EBS Volume?

• EBS volumes can be detached from an instance explicitly or by terminating the instance
• EBS root volumes are often detached by stopping the instance
• EBS data volumes, attached to a running instance, can be detached by unmounting the volume from the instance first.
• If the volume is detached without being unmounted, it might result the volume being stuck in the busy state and could possibly damaged the file system or the data it contains
• EBS volume are often force detached from an instance, using the Force Detach option, but it’d cause data loss or a corrupted filing system because the instance does not get a chance to flush filing system caches or filing system metadata
• Charges are still incurred for the volume after its detachment

47. How to connect EBS volume to multiple instances?

We can’t be ready to connect EBS volume to multiple instances. Although, you’ll connect various EBS Volumes to one instance.

48. Will I be billed for the IOPS provisioned on a Provisioned IOPS volume when it is disconnected from an instance?

Yes, you’ll be billed for the IOPS provisioned when it’s disconnected from an instance. When a volume is detached, we recommend you think about creating a snapshot and deleting the quantity to scale back costs. For more information, see the “Underutilized Amazon EBS Volumes” cost optimization sign up Trusted Advisor. This item checks your Amazon EBS volume and warns when volumes appear to be underused and configurations.

49. Do your prices include taxes?

Except as otherwise noted, our prices are exclusive of applicable taxes and duties, including VAT and applicable nuisance tax . With a Japanese customers billing address, use of AWS services is subject to Japanese Consumption Tax.

50. What factors can affect the performance consistency of my HDD-backed volumes?

EBS-optimized instances are designed to supply consistent performance attached Cold HDD volumes and Optimized HDD volume, delivering within 10% of the expected throughput performance 99% of the time in a given year. There are several factors that could affect the level of consistency you see. For example, the relative balance between random and sequential I/O operations on the quantity can impact your performance. Too many random small I/O operations will quickly deplete your I/O credits and lower your performance right down to the baseline rate. Your throughput rate can also be lower counting on the instance selected. Although st1 can drive throughput up to 500 MB/s, performance is going to be limited by the separate instance-level limit for EBS traffic. Another factor is taking a snapshot which can decrease expected write performance right down to the baseline rate, until the snapshot completes. This is specific to st1 and sc1.