Disaster Recovery + Migrations Flashcards
What is RPO?
Recovery Point Objective:
It’s basically how often you run backups. Or the time between your latest backup and the time of a disaster.
When a disaster happens, the time between the RPO and the disaster is the time in which data is lost.
For example if you back up data every hour. Your RPO is of 1 hour. When disaster strikes, you can go back to an hour ago to recover your data. So the data you lose is between the time of the disaster and the latest backup you have.
Which value identifies how much data loss you are willing to accept in case a disaster happens?
The RPO: Recovery Point Objective
What happens between the RPO time and the time a disaster strikes?
The data you processed is lost.
If you back up your data once a week. What is your RPO?
RTO = 1 week.
What is RTO?
RTO is the amount of downtime an application has or can have.
RTO is the downtime between the time of a disaster and the time your are back in production. (Meaning a replica was activated or a backup was restored and put into production, etc).
What are the disaster recovery strategies?
Backup and Restore
Pilot Light
Warm Standby
Hot Site / Multi Site approach
What are warm and cold disaster recovery setups?
Colder have slower RPO and RTO, warmer have faster RPO and RTO.
For example backup and restore is cold, since it has low rpo and rto compared to site recovery strategies or replication strategies.
What are some backup and restore strategies in AWS?
Backup Examples:
Backup data from corporate DC into S3 and through storage gateway, and move it to glacier with lifecycle policies.
This could have an RPO of 1 day for example.
Or once a week you send a snowball device with tons of data from your dc to an s3 glacier bucket. Here your RPO will be of 1 week.
Also when using services in aws like EBS volumes, RDS, Redshift, you can schedule regular snapshots, you could have an RPO of 1 day, or 2 hours, or 1 hour, based on how frequently you run these snapshots.
These are all backup strategies, and have a higher RPO.
Restore Examples:
Use AMIs recreate EC2 instances and spin up your applications, or restore your RDS, etc, straight from your snapshot.
Restoring your data from backups takes a lot of times, so you get a high RTO as well.
RTO and RPO are high, but backup and restore is cheaper.
What is Pilot Light strategy?
It’s a disaster recovery strategy, in which a smaller version of your production systems (apps, databases, servers, configurations) is always up and running in the cloud. These are the “critical core” components of your systems. You only include what is critical for your business to operate, so that in case of a disaster it’s ready to run and to be scaled into production quickly.
How do you achieve having a version of your critical core running in the cloud? With continuous replication of those critical servers. For example a database.
Then in case of a disaster you can restore from backup the not so critical servers.
This will lower your RPO and RTO.
This could be from onpremises to the cloud. Or from a region in the cloud to another region.
What do you need to do in case of a disaster when using pilot light as a disaster recovery strategy?
Similar to backup and restore, but your critical systems will be already running somewhere else, for example the cloud, so you only need to add the restored not so critical systems.
What is Warm Standby?
All your servers are ready to go in the cloud, but in a minimal size.
Then upon a disaster, you can scale them in the moment to production load.
This could be from onpremises to the cloud. Or from a region in the cloud to another region.
Scaling can be triggered with alarms and ASG in case of EC2, or RDS scaling.
Lower RTO because all backup resources are already running and only need to be scaled so they can meet the necessary resources for production.
More expensive than pilot light because you have more extra resources up on standby.
What role does Route 53 take in disaster recovery situations?
Route 53 can do the failover of your infrastructure when a disaster occurs in your onpremises DC, or in an AWS region. Destination would be another aws region.
Route 53 can reroute unhealthy resources to backup resources, thus performing failovers.
What is the Multi Site / Hot Site approach?
It’s a very low RTO (Minutes or seconds).
You have full production scale running both onpremises and on aws cloud. (Or only on cloud using 2 AWS regions)
This would be an active active setup, with route 53 routing traffic to both sites.
The most expensive option. Lowest RTO and RPO.
Multi DC type of infrastructure.
What are great backup options when backing up data from onpremises to the cloud?
Snowball
Storage Gateway
Which service helps you migrate DNS from a region to another, or from onpremises to aws?
Route 53
What is Database Migration Service? What are it’s characteristics?
DMS:
Quickly and securely migrate DBs from anywhere to the aws cloud.
It performs live migrations. DB remains available during the mgiration.
You can enable continuous data replication.
How does it work?
You need to create an EC2 instance that will run DMS, and it will perform the migration tasks.
There is also a serverless option that doesnt use EC2.
DMS can run in multi AZ.
Uses schema conversion tool for different database engines.
What is SCT: Schema Conversion Tool?
DMS runs it in an EC2 instance, or serverless, when your migration source and destination databases schemas have different engines, meaning different types of databases, for example migration from Oracle to MySQL, etc. (You dont need to run SCT with DMS if the source and destination databases have the same engine)
How can you migrate an RDS database to Aurora MySQL?
Option 1:
Take a snapshot of your RDS MySQL DB, and restore it into an Aurora MySQL DB. (You have some downtime while you switch the active database from RDS to Aurora).
Option 2:
Create a read replica in aurora for your RDS MySQL. This is possible.
Once replica lag is 0, promote it as its own DB Cluster. (No downtime, but takes longer to replicate the read replica and costs more money).
Option 3 From Onpremises:
Can migrate to s3 with percona backup, then create an aurora database from this backup.
Option 4 From Onpremises:
Create an Aurora MySQL DB. Then use mysqldump utility to migrate MySQL to Aurora. This is slower than s3 method.
Option 5: If both databases are up and running you should use DMS.
(The same goes for PostgreSQL, but for PostgreSQL any DBbackup utility works, contrary to MySQL that only supports Percona Backup)
How do you export an EC2 instance to onpremises?
With VM Import /Export. VM Import /Export can be used through the CLI.
How do you run Amazon Linux instances onpremises?
You can download the AMI as an iso file and upload it to onpremises platforms like vmware, kvm, virtualbox, hyper-v, etc.
What is AWS Server migration service?
To perform incremental replication of your onpremises servers.
How do you migrate existing onpremises applications to EC2?
With VM Import / Export.
Also great for disaster recovery.
What is Application Discovery Service?
To gather information about your current onpremises infrastructure, and plan a migration to aws.
What is AWS Backup?
An AWS managed service. It allows you to cantrally manage and automate backup of your AWS Services.
Supports: EC2, EBS, S3, RDS, Aurora, DynamoDB, DocumentDB, Neptune, FSx, EFS, Storage Gateway (Volume Gateway), etc.
Supports Cross Region Backups, and Cross Account Backups.
Features:
Point in time recovery for DB services, on demand and scheduled backups, tag based backup policies
Backup plans with whatever frequency, backup window, transition backups to cold storage, retention periods.
Data is backed up to S3.
With AWS Backup Vault Lock, you can enforce a WORM policy, meaning you can’t delete your backups from the s3 bucket.
How do you start planning your migration from onpremises to the aws cloud?
With AWS Application Discovery Service.
You can run agentless or agent discovery in your vsphere infrastructure.
It collects data on your servers and the network connectivity between them.
This data can be viewed from the AWS Migration Hub service.
What is AWS Migration Hub?
Where you can see the data like server utilization and dependency mappings collected by the AWS Application Discovery Service from your onpremises vmware infrastructure.
How do you execute your migration from onpremises to the aws cloud?
With the AWS Application Migration Service (MGN)
After you collected all necesary data, and planned your migration, you can use this service.
It’s a lift and shift solution, that simplifies migration applications to AWS.
Converts your physical, virtual, and cloud based servers to run natively on AWS.
How does AWS Application Migration Service (MGN) work?
Staging process:
It executes continuous replication of your servers, to low cost aws version of your resources. Once you are ready you perform a cutover you move into production.
Production:
Move from staging to production by getting bigger instances and volumes that match your production standards.
What is VMware Cloud on AWS?
This is for users who have VMware vSphere Clusters, and manage them through their VMware Software. And they want to extend their Datacenter Capacity to AWS, but they want to keep managing everything through their VMware Software.
Thanks to VMware Cloud on AWS, you can extend your entire VMware infrastructure, to also be on AWS. You can run vSphere, VSAN, NSX, etc from AWS.
Use cases: Now you can extend computer power from onpremises to the cloud, or storage power.
Now you have an extra disaster recovery strategy.
Now you can access AWS Services and use them as well in conjunction with your vSphere resources.
As part of your Disaster Recovery plan, you would like to have only the critical infrastructure up and running in AWS. You don’t mind a longer Recovery Time Objective (RTO). Which DR strategy do you recommend?
Pilot Light
You would like to get the Disaster Recovery strategy with the lowest Recovery Time Objective (RTO) and Recovery Point Objective (RPO), regardless of the cost. Which DR should you choose?
Multi Site / Hot Site
Which of the AWS Disaster Recovery strategies has the highest Recovery Point Objective (RPO) and Recovery Time Objective (RTO)?
Backup and Restore
You want to make a Disaster Recovery plan where you have a scaled-down version of your system up and running, and when a disaster happens, it scales up quickly. Which DR strategy should you choose?
Warm Standby
You have an on-premises Oracle database that you want to migrate to AWS, specifically to Amazon Aurora. How would you do the migration?
Use AWS Schema conversion tool to convert the schema, and then use AWS DMS to migrate the data.
You are running many resources in AWS such as EC2 instances, EBS volumes, DynamoDB tables… You want an easy way to manage backups across all these AWS services from a single place. Which AWS offering makes this process easy?
AWS Backup
AWS Backup enables you to centralize and automate data protection across AWS services. It helps you support your regulatory compliance or business policies for data protection.
A company planning to migrate its existing websites, applications, servers, virtual machines, and data to AWS. They want to do a lift-and-shift migration with minimum downtime and reduced costs. Which AWS service can help in this scenario?
MGN: AWS Application Migration Service
A company is using VMware on its on-premises data center to manage its infrastructure. There is a requirement to extend their data center and infrastructure to AWS but keep using the technology stack they are using which is VMware. Which AWS service can they use?
VMware Cloud on AWS
A company is using RDS for MySQL as their main database but, lately they have been facing issues in managing the database, performance issues, and the scalability. And they have decided to use Aurora for MySQL instead for better performance, less complexity and less administrative tasks required. What is the best way and most cost-effective way to migrate from RDS for MySQL to Aurora for MySQL?
Create a snapshot of the RDS MySQL database, and restore it to an Aurora MySQL database.
Which AWS service can you use to automate the backup across different AWS services such as RDS, DynamoDB, Aurora, and EFS file systems, and EBS volumes?
AWS Backup
