Showing posts with label block. Show all posts
Showing posts with label block. Show all posts

April 19, 2022

Top 20 AWS Elastic Block Store (EBS) Interview Questions and Answers


            The Amazon Elastic Block Store (EBS) is a block storage solution for long-term data storage. Amazon EBS is a highly available block level storage volume that is suited for EC2 instances. General Purpose (SSD), Provisioned IOPS (SSD), and Magnetic are the three types of volume available. The performance, attributes, and pricing of these three volume categories vary. For usage with Amazon EC2 instances, Amazon Elastic Block Store (EBS) provides block level storage volumes. Amazon EBS volumes are off-instance storage that lasts indefinitely, regardless of how long an instance is running.

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Ques.1 ): What is Elastic Block Store, and how does it work?


Amazon Elastic Block Store (EBS) is a high-performance, easy-to-use block storage service designed for use with Amazon Elastic Compute Cloud (EC2) for both throughput and transaction-intensive workloads at any scale. Amazon EBS is a storage service that provides block-level storage volumes for AWS EC2 instances. EBS volumes are off-instance storage that lasts indefinitely. It's a simple-to-use block storage service designed to integrate with AWS EC2 for high-throughput and transaction-intensive operations at any scale.

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Ques. 2): What are the advantages of using Amazon EBS?


Storage that is both reliable and secure - Each EBS volume will automatically respond to its Availability Zone in order to protect against component failure. Secure - You may decide who has access to which EBS volumes using Amazon's flexible access control policies. Access control combined with encryption provides a robust data defense-in-depth security technique. Higher performance - Amazon EBS makes advantage of SSD technology to deliver data results with consistent application I/O performance. Simple data backup - Take point-in-time snapshots of Amazon EBS volumes to save data backup. Benefits of Amazon EBS are as follows:

Reliable and Secure Storage - It automatically respond to its availability zone protecting from component failure.

Secure - It allows us to specify access EBS volumes.

Higher Performance - Delivers data results with consistent performance.

Easy Data Backup - Takes taking point-in-time snapshots of Amazon EBS volumes.

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Ques. 3): What is EBS Block Express, and how does it work?


EBS Block Express is the next version of Amazon EBS storage server architecture, designed to provide the highest levels of performance for block storage at cloud scale with sub-millisecond latency. Block Express accomplishes this by communicating with Nitro System-based EC2 instances via Scalable Reliable Datagrams (SRD), a high-performance, low-latency network protocol. This is the same high-performance, low-latency network interface used in Elastic Fabric Adapter (EFA) for High Performance Computing (HPC) and Machine Learning (ML) applications for inter-instance communication. Block Express also provides modular software and hardware building blocks that can be built in a variety of ways, allowing us to design and deliver greater performance and new features more quickly.

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Ques. 4): What are the various types of EBS volumes?


There are five types of EBS volumes available as below:

General Purpose SSD (gp2): The SSD (Solid State Drive) is the volume that EC2 defaults to as the root volume of your instance. SSDs are many times faster than HDDs for modest input/output tasks (Hard Disk Drive). It has a good price-performance ratio (measured in IOPS - Input-Output Operations per second).

Provisioned IOPS SSD (io1): This is the most costly and time-consuming EBS volume. They're designed for applications that require a lot of I/O, such as huge Relational or NoSQL databases.

Throughput Optimized HDD (st1): These are low-cost magnetic storage volumes whose performance is measured in terms of throughput.

Cold HDD (sc1): These are even less expensive magnetic storage options than Throughput Optimized. They are intended for large, sequential cold workloads, such as those found on a file server.

Magnetic (standard): These are older generation magnetic drives that are best suited for workloads with infrequent data access.

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Ques. 5): When would I want to use FSR (Fast Snapshot Restore)?


If you are concerned about data access latency when restoring data from a snapshot to a volume and wish to prevent the first performance hit during initialization, you should enable FSR on snapshots. Virtual desktop infrastructure (VDI), backup and restore, test/dev volume copies, and booting from custom AMIs are all examples of use cases for FSR. When you enable FSR on your snapshot, you'll get better and more predictable results anytime you need to restore data from it.

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Ques. 6): What are the different kinds of EBS Volumes?


General Purpose EBS (SSD) This volume type is appropriate for small and medium workloads, such as root disc EC2 volumes, small and medium database workloads, and workloads that access logs regularly. By default, SSDs support 3 IOPS/GB, which means that a 1 GB volume will provide 3 IOPS and a 10 GB volume will provide 30 IOPS. One volume's storage size ranges from 1 GB to 1 TB. For one month, each volume costs $0.10 per GB.

IOPS provisioned (SSD) This volume type is best for transactional workloads that require a lot of I/O, as well as large relational, EMR, and Hadoop workloads. IOPS SSDs support 30 IOPS/GB by default, so a 10GB volume will provide 300 IOPS. One volume's storage size ranges from 10GB to 1TB. For supplied storage, one volume costs $0.125 per GB per month and $0.10 per provisioned IOPS per month.

Magnetic Volumes from EBS Previously, it was known as standard volumes. This volume type is suited for workloads that require infrequent data access, such as data backups for recovery, log storage, and so on. One volume's storage size ranges from 10GB to 1TB. For provisioned storage, one volume costs $0.05 per GB per month and $0.05 per million I/O requests. There are 3 types of EBS Volume:

·      The EBS General Purpose (SSD) volume is suitable for small and medium workloads, such as those on the Root Disc EC2.

·      Povisioned IOPS (SSD) volume is ideal for the most I/O heavy and big workloads, such as Hadoop.

·      EBS Magnetic Volumes, also known as standard volumes, are a type of magnetic volume. It is appropriate for tasks such as data backups and log storage.

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Ques. 7): How can I change an existing EBS volume's capacity, performance, or type?


It's simple to change the volume configuration. Using a single CLI call, API call, or a few console clicks, you can expand capacity, optimise performance, or change your volume type with Elastic Volumes. See the Elastic Volumes documentation for more information on Elastic Volumes.

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Ques. 8): What is the Amazon Web Services (AWS) Key Management Service (KMS)?


AWS KMS is a managed service that allows you to easily produce and maintain the encryption keys that are used to encrypt your data. AWS Key Management Service works with other AWS services like Amazon EBS, Amazon S3, and Amazon Redshift to make it simple to encrypt your data with encryption keys you control. AWS Key Management Service and AWS CloudTrail are connected to provide you with logs of all key usage to help you satisfy your regulatory and compliance requirements.

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Ques. 9): How can we change default root EBS size in cloudformation?


Use BlockDeviceMappings to approach

 "BlockDeviceMappings": [


            "DeviceName": "/dev/xvda",

            "Ebs": {

              "VolumeType": "io1",

              "Iops": "300",

              "DeleteOnTermination": "false",

              "VolumeSize": "30"





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Ques. 10): What happens if the 'deleteOnTermination' flag isn't set on all of my linked instances?


The configuration of the last associated instance that is terminated determines the volume's deleteOnTermination behaviour. Enable or disable 'deleteOnTermination' for all instances to which the volume is associated to ensure predictable remove on termination behaviour.

Enable 'deleteOnTermination' for all instances to which the volume is attached if you want the volume to be erased when the attached instances are terminated. Disable 'deleteOnTermination' for all attached instances if you want to keep the volume after the attached instances have been terminated. See the Multi-Attach technical documentation for further information.

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Ques. 11): How to Set Up Amazon EBS?


Use the following steps for setting up Amazon EBS:

STEP 1 - Create Amazon EBS volume.

STEP 2 - Store EBS Volume from a snapshot.

STEP 3 - Attach EBS Volume to an Instance.

STEP 4 - Detach a volume from Instance.

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Ques. 12): Is it necessary to unmount volumes before taking a snapshot?


No, while the volume is mounted and in use, snapshots can be taken in real time. Snapshots, on the other hand, only capture data that has been written to your Amazon EBS volume, so any data that has been cached locally by your application or OS may be missed. We recommend removing the volume cleanly, issuing the snapshot command, and then reattaching the volume to ensure consistent snapshots on volumes associated to an instance. Shutting down the computer to take a clean snapshot of Amazon EBS volumes that function as root devices is recommended.

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Ques. 13): Does the read and write I/O size of my application effect the rate of IOPS I get from my Provisioned IOPS SSD (io2 and io1) volumes?


It certainly does. The IOPS rate you obtain when you provision IOPS for io2 or io1 volumes is determined by the I/O size of your application reads and writes. The base I/O size for provisioned IOPS volumes is 16KB. So, if you provisioned a volume with 40,000 IOPS for an I/O size of 16KB, it will achieve that size and 40,000 IOPS. If you increase the I/O size to 32 KB, you can get up to 20,000 IOPS, and so on.

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Ques. 14): How do I transfer files from one EBS to another?


We need to attach to an instance for copying files from one EBS to another EBS, and we can store the contents on a third storage option if the volumes aren't attached to instances.Follow the following steps for doing the same:

·      Start a temporary instance.

·         Use a larger size for higher IO bandwidth.

·         Attach both EBS volumes to the instance and mount them as, say, /vol1 and /vol2.

·         Copy the files from /vol1 to /vol2.

·         Unmount the volumes, detach the EBS volumes, terminate the temporary instance.

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Ques. 15): Does the size of the read and write I/O in my application effect the rate of throughput I obtain from my HDD-backed volumes?


Yes. The throughput rate you get is determined on the read and write I/O sizes of your application. Reads and writes in 1MB I/O sizes are processed by HDD-backed volumes. Even though the actual I/O size is smaller, sequential I/Os are merged and processed as 1 MB units, whereas non-sequential I/Os are treated as 1MB units. While a transactional workload with small, random IOs, such as a database, will not perform well on HDD-backed volumes, sequential I/Os and huge I/O sizes will reach the claimed st1 and sc1 performance for a longer length of time.

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Ques. 16): What is the maximum storage capacity of an EBS device?


At the moment, EBS supports a maximum volume size of 16 TiB. This suggests that you can construct an EBS volume with a capacity of up to 16 TiB, but whether the OS recognises all of that capacity is dependent on the OS's own design characteristics and the partitioning of the volume.

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Ques. 17): When an EBS volume fails, how do you make it available with no downtime and link it to an EC2 instance?


You can use a load balancer and auto scaling to make an EBS volume available with no downtime. If the ec2 instance goes down due to autoscaling, a new instance will be launched, and you can use the shell script to add commands to map to the EBS. We can also take frequent backups and replace the EBS volume with the most recent backup or snapshot if the EBS fails.

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Ques. 18): When an Amazon EC2 instance is terminated, what happens to my data?


Data stored on an Amazon EBS volume, unlike data stored on a local instance store (which persists just as long as the instance is alive), can persist regardless of the instance's life. As a result, we suggest that you only use the local instance storage for transient data. We recommend using Amazon EBS volumes or backing up data to Amazon S3 for data that requires a higher level of durability. If you're using an Amazon EBS volume as a root partition, make sure the Delete on termination flag is set to "No" if you want the Amazon EBS volume to survive the instance's life.

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Ques. 19): What can I expect from Amazon EBS volumes in terms of performance?


Provisioned IOPS SSD (io2 Block Express, io2, and io1), General Purpose SSD (gp3 and gp2), Throughput Optimized HDD (st1), and Cold HDD are the seven volume types offered by Amazon EBS (sc1). These volume kinds differ in terms of performance and cost, allowing you to adjust your storage performance and cost to your applications' requirements. Between EC2 instances and EBS, the typical latency is in the single digit milliseconds. See the EBS product specifics page for more information about performance.


Ques. 20): What's the difference between io2 Block Express and io2?


For all EC2 instances, io2 volumes provide high-performance block storage. Attaching io2 volumes to R5b instance types, which operate on Block Express and provide 4x the performance of io2, is recommended for applications that demand even more performance. With sub-millisecond average IO latency, you can achieve up to 64 TiB capacity, 256,000 IOPS, and 4,000 MB/s throughput from a single io2 volume.




November 22, 2021

Top 20 AWS Solution Architect Interview Questions & Answers


Ques: 1). I have a few private servers, and I also use the public cloud to share some workloads. What kind of structure is this?


The hybrid cloud is created when both private and public cloud services are combined. When private and public clouds are virtually housed on the same network, it is easy to comprehend a hybrid architecture.


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Ques: 2). What's the difference between stopping and terminating an instance?


Stopping an Instance: When you stop an instance, it goes through a standard shutdown process. Its Amazon EBS volume, on the other hand, remains attached, and you may restart the instance whenever you want. The advantage of stopping an instance is that you will not be charged for that instance once it has been terminated.

Terminating an Instance: When an instance is terminated, it goes through a normal shutdown and any Amazon EBS volumes attached to the instance are destroyed at the same time. You cannot restart an instance once it has been terminated.

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Ques: 3). What distinguishes a Spot Instance from a Reserved or On-Demand Instance?


Pricing models include Spot instances, Reserved instances, and On-demand instances. Users can buy compute power without making an upfront investment using a spot instance, however they must pay hourly, which is lower than the on-demand instance fee in each area.

Spot instances are analogous to bidding, and the Spot Price is the bidding price for these instances. The price may fluctuate due to availability and demand, but you will never pay more than the maximum amount mentioned. In the event that spot prices rise above the maximum price, the EC2 instances will automatically shut down. The opposite is not true: if spot prices fall, EC2 Instances are not instantly launched. It's possible to do it manually.

There is no obligation on the part of the user for Spot and On-demand instances. In the case of Reserved Instances, however, one must keep to the time period that was previously selected.

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Ques: 4). In AWS, which instance type should you use to deploy a 4-node Hadoop cluster?


Each Hadoop cluster is built on a master-slave model, in which the master system processes the data and the slave machine acts as a data node. Because all of the processing is done on the master system, it requires a high-capacity CPU and RAM, and because all of the storage is done on the slave machine, a large hard disc is required.

You have complete control over the machine's setup based on the workload. If you don't want to configure the computer manually, you can immediately launch an Amazon EMR instance that will do it for you. You dump the data to be processed in S3, EMR picks the data from there, processes it, and dumps it back to the S3.

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Ques: 5). Is a single Elastic IP address sufficient for all running instances?


Each instance has its own public and private addresses. When an instance is stopped or terminated, it returns a private address that is unique to that instance. Similarly, until the instance is halted or terminated, a public address is connected only with it. However, an EIP (Elastic IP address) can be assigned to an instance that will remain active until the user detaches it manually. In the event that you are hosting multiple websites on your EC2 server, you will require different EIP numbers.

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Ques: 6). Is it possible to use an S3 bucket with EC2 Instances as well?


Yes, it's possible to utilise it with root devices that are backed up by local instances storage. Amazon S3 gives developers access to the same dependable and expensive data storage infrastructure that Amazon uses to power its global websites.

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Ques: 7). Explain how to use Amazon Instance to vertically scale.


The following are the steps to vertically scale on Amazon:

  1. Upgrade from the current instance to a new larger instance.
  2. Pause the previous instance and discard it by detaching the root web volumes from the servers.
  3. Now stop the live instance and also detach its root volume.
  4. Attach the root volume to the new server after you note the unique device ID.
  5. And finally, restart it.

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Ques: 8). What does a buffer do in Amazon web services?


The buffer is used to make the system more robust for managing traffic or load by synchronising multiple components. The components, in general, receive and process requests in an uneven manner. When the buffer is used, however, the components are balanced and operate at the same speed, ensuring that proper service is provided.

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Ques: 9). What kind of performance can Elastic Block Storage provide? How do you back it up and improve the results?


The performance of elastic block storage fluctuates, and it might go above and below the SLA performance threshold. SLA gives an average disc I/O rate, which can irritate performance experts who want a server's disc throughput to be consistent and reliable. This is not the case with virtual AWS instances. A graphical user interface, such as elasticfox, can be used to backup EBS volumes, or an API call can be used to leverage the snapshot feature. Using Linux software raid and striping over four drives can further increase performance.


Ques: 10). Distinguish between an on-demand and a spot instance.


Spot Instances are unused Amazon EC2 instances that can be bid on. The spot instance will be launched once the bid exceeds the current spot price (which changes in real-time based on demand and supply). If the spot price exceeds the bid price, the instance can be cancelled at any time and with only 2 minutes' notice. The best technique to determine the best bid price for a spot instance is to consult the AWS console's price history for the previous 90 days. Spot instances have the benefit of being cost-effective, but the disadvantage is that they can be cancelled at any time. Spot instances are ideal to use when –

There are optional nice to have tasks.

You have flexible workloads which can be run when there is enough compute capacity.

Tasks that require extra computing capacity to improve performance.

On-demand instances are available anytime you need them, and you must pay on an hourly basis for the time you utilise them. These instances can be released as soon as they are no longer needed, and there is no commitment required up front. Unlike spot instances, AWS guarantees the availability of these instances.

The recommended practise is to start a few on-demand instances that can provide a minimal level of assured compute resources for the application and then add on a few spot instances as needed.


Ques: 11). What is Amazon EMR and how does it work?


Amazon EMR is a surviving cluster stage that is useful in data structures since it demonstrates how things work before they are notified. On Amazon Web Services, Apache Spark and Apache Hadoop are useful for analysing massive amounts of data. Data for analytics purposes and marketing intelligence workloads can be prepared using Apache Hive. It also makes use of other open-source ideas that are applicable.


Ques: 12). Is it possible to scale an Amazon Instance vertically? If so, how do you go about doing it?


The steps to vertically scale an Amazon Instance are as follows –

    1. Spin up a larger Amazon instance than the existing one.
    2. Pause the exisiting instance to remove the root ebs volume from the server  and discard.
    3. Stop the live running instance and detach its root volume.
    4. Make a note of the unique device ID and attach that root volume to the new server.
    5. Start the instance again.


Ques: 13). How will you prepare an instance to serve traffic by configuring it with the application and its dependencies?


The use of lifecycle hooks can help you do this. They are useful because they allow you to halt the construction or termination of an instance so that you can sneak a peek inside and do specific activities such as configuring the instance, downloading relevant files, and performing any other steps necessary to get the instance ready. There can be many lifecycle hooks in each auto scaling group.


Ques: 14).  How can EC2 instances running in a VPC be protected?


AWS Security groups connected with EC2 instances can help you protect EC2 instances running in a VPC by enforcing protocol and port access security. You can secure access to the EC2 instance by configuring both INBOUND and OUTBOUND traffic. AWS security groups are similar to firewalls in that they contain a collection of rules that filter traffic entering and exiting an EC2 instance and prevent unauthorised access to those instances.


Ques: 15). What are some of the most important security best practises in Amazon EC2?


To limit access to your AWS resources, create unique IAM (Identity and Access Management) users. Creating a unique IAM user gives each user their own set of credentials, allowing them to be given varying permissions based on their access needs.

  • Secure the AWS Root account and its access keys.
  • Harden EC2  instances by disabling unnecessary services and applications by installing only necessary software and tools on EC2 instances.
  • Grant least privileges by opening up permissions that are required to perform a specific task and not more than that. Additional permissions can be granted as required.
  • Define and review the security group rules on a regular basis.
  • Have a well-defined strong password policy for all the users.
  • Deploy anti-virus software on the AWS network to protect it from Trojans, Viruses, etc.


Ques: 16). What are the key characteristics of a traditional load balancer in EC2?


The high availability functionality distributes traffic among EC2 instances in a single or several availability zones.

This assures a high level of incoming traffic availability.

Based on the findings of the health check, a traditional load balancer can decide whether or not to route traffic.

By defining security groups in a VPC, you may achieve safe load balancing within a network.

Sticky sessions are supported by traditional load balancers, which ensure that a user's traffic is always routed to the same instance for a consistent experience.


Ques: 17).  What are the possible connection issues you encounter when connecting to an EC2 instance ?


    • Unprotected private key file
    • Server refused key
    • Connection timed out
    • No supported authentication method available
    • Host key not found,permission denied.
    • User key not recognized by the server, permission denied.


Ques: 18). What's the difference between stopping and terminating an EC2 instance?


When you end an EC2 instance, it goes into a standard shutdown mode and is moved to the stop state. When an EC2 instance is terminated, it is put into a suspended state, and any EBS volumes attached to it are erased and can't be restored.


Ques: 19). How can you use EBS to automate EC2 backups?


Creating snapshots of EBS volumes can be used to back up AWS EC2 instances. Amazon S3 is utilised to store the snapshots. Snapshots can capture all of the data in EBS volumes and produce precise replicas of it. The snapshots can then be cloned and relocated to another AWS region, ensuring that sensitive data is kept safe and secure.

Stopping the instance or detaching the EBS volume that will be backed up is suggested before executing AWS EC2 backup. Any failures or problems will not effect newly produced snapshots as a result of this.

The following steps must be followed to back up an AWS EC2 instance:

  1. Sign in to the AWS account, and launch the AWS console.
  2. Launch the EC2 Management Console from the Services option.
  3. From the list of running instances, select the instance that has to be backed up.
  4. Find the Amazon EBS volumes that are attached locally to that particular instance.
  5. List the snapshots of each of the volumes, and specify a retention period for the snapshots. A snapshot has to be created of each volume too.
  6. Remember to remove snapshots that are older than the retention period.


Ques: 20). What is a denial-of-service (DoS) attack, and how do you respond to one?


When a malicious attempt is made to affect the availability of a certain system, such as an application or a website, a Denial of Service (DoS) attack occurs. When an attacker uses many sources to generate a DDoS attack, it is known as a Distributed Denial of Service attack. DDoS assaults are usually classified according to whatever layer of the Open Systems Interconnection (OSI) model they target. The Network, Transport, Presentation, and Application levels, which correspond to layers 3,4,6, and 7, are the most typical targets for DDoS attacks.