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AWS Elastic Cloud Compute (EC2)
Terms in this set (84)
Elastic Compute Cloud. Web service providing resizeable compute capacity in the cloud. Reduces the time required to obtain and boot the new server to mins.
What are the EC2 pricing models?
1. On demand,
What length are the new EC2 and EBS instance IDs?
17 characters (<resource identifier>-<17 characters>, e.g. "i-1234567890abcdef0")
What is a reservation ID?
Every instance launched by EC2 has a reservation ID. The ID has a one-to-one relationship with an instance launch request, but can be associated with more than one instance if you launch multiple instances using the same launch request.
Are there any concerns about the new instance IDs and windows instances?
Windows will automatically truncate the name to 15 characters to adhere to NetBIOS naming conventions. Due to this, you may see duplicate computer names at 15 characters. Recommend using a unique naming scheme to avoid complications.
How many instances can I run in EC2?
Limited to up to 20 On-Demand Instances, purchasing 20 Reserved Instances, and requesting Spot Instances per your dynamic Spot limit per region. If you need more instances, complete the Amazon EC2 instance request form with your use case and your instance increase will be considered. Limit increases are tied to the region they were requested for.
What is an on demand instance?
Pay for compute capacity by the hour with no long-term commitments. Good for users that want low cost w/out up-front payment or commitment. Good for short term or spikey work loads that cannot be interrupted.
What is a reserved instance?
Provides capacity reservation and offers significant discount on the hourly charge for an instance (up to 75% off). Three payment options: all upfront, partial upfront, no upfront.
What are spot instances?
Bid for unused EC2 capacity. Prices set by Amazon, fluctuate depending on the supply and demand for capacity.
True or False. Spot instances are good for applications that must run at specific times.
False. They are only good for applications that have flexible start and end times. The instances will be terminated by AWS if someone is willing to pay more for compute time.
True or False. You will get the last hour of your Spot instance for free upon termination.
False. You only get the last hour free if AWS terminates the instance. If you terminate it, you still have to pay for the time used.
How do you bid on a spot instance?
Place a Spot Instance request, specifying the instance type, Availability Zone, number of Instances, and the maximum price you are willing to pay per instance hour. (like Ebay)
What are the EC2 instance types?
2. M3, M4
3. C3, C4
What instance type is best for small web servers or small DBs (SQLite)?
T2. Lowest cost, general purpose.
What instance type is the lowest cost?
What instance type is best for general application servers?
M3 or M4.
What instance types are best for CPU intensive applications or DBs?
C3 or C4. Compute optimized.
What instance types are best for memory intensive applications or DBs?
R3. Memory (RAM) optimized.
What instance types are best for video encoding, machine learning, or application streaming?
G2. Graphics and general purpose GPU.
What instance types are best for NoSQL DBs or data warehousing?
I2. High speed storage.
What instance types are best for Fileservers, data warehousing, or applications like Hadoop?
D2. Dense storage.
What does DIRTMCG stand for?
Tiny general purpose (T2),
Main choice for general use (M3/4),
Elastic Block Storage. Persistent block level storage volumes for use with Amazon EC2 instances. Auto-replicated w/in AZ. Can install a file system, run DB, or otherwise use like normal drive.
What are the 3 types of EBS storage?
1. General Purpose (SSD),
2. Provisioned IOPS (SSD),
3. Magnetic (standard)
What is a general purpose EBS volume?
SSD-backed, used for boot volumes, data, or databases.
Up to 16TB.
Max IOPS/volume = 10k.
Max IOPS burst = 3k <= 1TB.
Max throughput = 160MB/sec.
Price = $.10/GB/mo
What is a provisioned IOPS EBS volume?
SSD-backed, used for I/O intensive applications, relational DBs, or NoSQL DBs.
Up to 16TB.
Max IOPS/volume 20k.
Max IOPS burst = 3k <= 1TB.
Max throughput 320MB/sec.
Price $.125/GB/mo + $.065 provisioned IOPS.
What is a magnetic EBS volume?
Magnetic disk-backed, used for infrequent data access.
Up to 1TB.
Max IOPS/volume = 40-200.
Max IOPS burst = hundreds.
Max throughput = 40-90 MB/sec.
Price $.05/GB/mo + $.05/million I/O.
True or False. You can mount an EBS volume to multiple instances at the same time.
False. EBS volumes can only be mounted to a single instance at a time.
True or False. You can delete a snapshot of an EBS volume that is used as the root device of a registered AMI.
False. You must deregister the AMI before deleting it.
True or False. Volumes exist on S3.
False. Volumes exist on EBS.
Logical grouping of instances w/in an AZ. Enables applications to participate in a low-latency, 10Gbps network.
Placement group is ideal for what type of instances?
Instance requiring high network throughput and low latency across a single AZ.
What are the Linux AMI virtualization types?
HVM and PV
Hardware Virtual Machine. Run an OS directly on the VM without any modification, as if it were on the hardware. Recommended for best performance.
Paravirtual Machine. Run on host hardware that does not have explicit support for virtualization. Cannot take advantage of special hardware extensions. Once performed better than HVM, but new HVM enhancements equalized the gap.
What is the purpose of tagging an instance?
Identification and billing purposes.
True or False. You cannot encrypt a volume where an OS is installed.
True or False. Termination protection is turned off by default.
True. Can be turned on through console, CLI, or API. Cannot turn on for Spot instances or Auto Scaling group members.
True or False. Root volumes are configured to delete on instance termination.
True. This can be changed during or after instance creation.
What is a Security Group?
Acts as a virtual firewall that controls the traffic for one or more instances. Associate 1+ security groups with an instance. Add rules to each security group allowing traffic to/from associated instances.
True or False. If you edit a security group, the edits take effect immediately.
True. New rules are automatically applied to all instances that are associated with the security group.
True or False. If you allow an inbound port in a security group, you must also manually allow the same outbound port.
False. Ports are stateful. If you allow it inbound, it'll be allowed outbound too.
True or False. All inbound traffic is allowed by defualt.
False. All inbound traffic is blocked by default.
True or False. All outbound traffic is allowed by default.
True or False. You can only have 50 intances in a security group.
False. You can have any number of instances within a security group.
What storage service do volumes exist on?
Elastic Block Storage (EBS)
What storage service do snapshots exist on?
Simple Storage Service (S3) (object storage)
If you take a snapshot of a volume, what storage service is it saved on?
What is a snapshot?
A point in time copy of a volume. Backups are incremental. When you delete a snapshot, only the data exclusive to that snapshot is removed.
True or False. Snapshots of encrypted volumes are NOT encrypted by default.
True or False. Volumes restored from encrypted snapshots are also encrypted.
True or False. Encrypted snapshots can be shared with other AWS accounts and be made public.
False. Only unencrypted snapshots can be shared and made public.
True or False. Snapshots can be used across regions.
False. Snapshots are constrained to the region where they are created. Need to copy the snapshot to another region to use it there.
True or False. When creating a snapshot of a root volume, you don't need to stop the instance.
True (technically, but it will be done for you if you don't. Either way, it will be stopped.)
What is an instance store volume?
Temporary block-level storage located on disks physically attached to the host computer. Ideal for temporary storage of information that changes frequently, like buffers, caches, scratch data.
True or False. Instance store volumes cannot be stopped without losing data.
True. However, they can be restarted without losing data.
What is a RAID?
Redundant Array of Independent Disks
What are the benefits of RAID 0?
Striped, no redundency, good performance
What are the benefits of RAID 1?
What are the benefits of RAID 5?
Good for read, bad for write. AWS discourages this on EBS.
What are the benefits of RAID 10?
Striping and mirroring, good redundancy and performance.
What is the recommended practice for taking a snapshot of a RAID?
Freeze the filesystem OR unmount RAID array OR shut down the instance and then take the snapshot.
What is an AMI?
Amazon Machine Image. A copy of a VM with info required to launch a virtual server in the cloud.
What is the limit of images you can create from an AMI?
There isn't one.
What are the 3 parts of an AMI?
1. Template for the root volume,
2. Launch permissions controlling which AWS accounts can use the AMI,
3. Block device specifying the volumes to attach to the instance(s) when launched.
True or False. You can only share an AMI with specific AWS accounts.
False. You can also share AMIs with the public.
What are the recommended steps to harden your AMI?
1. Disable services and protocols that authenticate users in clear text (e.g. Telnet and FTP).
2. Do not start unnecessary network services on launch. 3. Securely delete all AWS credentials from disk and config files.
4. Securely delete any third-party credentials from disk and config files.
5. Securely delete any certificates or key material
6. Ensure installed software does not have default internal accounts and passwords.
7. Ensure the system does not violate the AWS Acceptable Use Policy.
True or False. AMIs are regional.
True. They are snapshots, so they cannot be used across regions. Must first be copied to the target region.
What is ELB?
Elastic Load Balancer. Automatically distributes incoming application traffic across multiple Amazon EC2 instances in the cloud.
True or False. You should use an IP address to target an ELB.
False. The IP may change. Always use the DNS name.
True or False. ELBs use health checks to determine if instances can receive traffic.
True. When it detects unhealthy Amazon EC2 instances, it no longer routes traffic to those instances.
What are sticky sessions?
ELB will route traffic to the same instances while the user continues to access your application using cookies.
What is CloudWatch?
A monitoring service for AWS cloud resources and the applications that run on them. Can collect/track metrics, collect/monitor log files, set alarms, and automatically react to changes in your AWS resources.
What features does basic CloudWatch monitoring include?
Every instance starts w/basic monitoring:
3 dashboards up to 50 metrics each/month,
polls every 5 mins,
5 GB of data ingestion, and
5 GB of archived storage per month.
More available at a price.
What can I do with CloudWatch?
2. Alarms that trigger actions or send notifications,
3. Events allowing you to respond to changes,
4. Install an agent on your instance that will aggregate, monitor, and store logs
True or False. I can add a role to an EC2 instance after the instance has been created and powered up.
False. Roles can only be added to an instance during creation.
True or False. Recommended practice is to store access keys on EC2 instances.
False. Recommended practice is to give permissions to a role allowing proper access, then assign the role to the instance. More secure and easier to maintain.
True or False. Roles are universal.
True. They can be used in any region.
What is Lambda?
Compute service where you can upload code and create a function. AWS takes care of provisioning and managing underlying host servers.
What are the 2 use cases for Lambda?
1. Event driven compute service, lambda runs in response to events
2. Run code in response to HTTP request using API Gateway or API calss using AWS SDKs
How will I be charged and billed for EC2 usage?
You pay only for what you use and there is no minimum fee. Pricing is per instance-hour consumed for each instance type. Partial instance-hours consumed are billed as full hours. No Data Transfer charge between two AWS within the same region.
What are billable EC2 instance-hours?
Any time your instances are in the 'running' state. Must stop or terminate the instance to avoid being billed.
If I have 2 instances in different AZs or regions, how will I be charged?
Each instance is charged for its data in and data out. Therefore, if data is transferred between these two instances, it is charged out for the first instance and in for the second instance.
What is an EC2 Compute Unit
The amount of CPU that is allocated to a particular instance is expressed in terms of these EC2 Compute Units. A consistent and predictable amount of CPU capacity used for billing purposes.
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