Simple Storage Service

AWS Storage Services:

• Amazon Elastic block Store - Need an instance to access it .
• Amazon elastic file System - You can configure instances to mount the file system
• Amazon s3 Glacier - Stores archival data( Data that we don't use frequently), It takes some time to retreive that data, high latency.
• AWS Storage gateway - A gateway to move data between different environments
• Snowball - moves data physically (copy and paste )
• Snowmobile - Moves a large amount of data physically
• Amazon s3 storage - It is an object store good at storing vast numbers of backups or user files.

Amazon s3(Simple storage service)

• It is flexible , durable(99.99999999999) with the help of checksum , Available , cost efficient , scalable , secure
• It works with the concept of object and buckets
• Object - data + Meta data(Data with key(file name) and version ID) - Meta data is automatically created by the system
• Bucket - container that holds objects

Note: When we go to s3 dashboard , the region changes to global indicating that the s3 service is global .

Creation of s3 bucket -

1. Click on create bucket

2. The name of the bucket should be globally unique

3. leave the remaining as default and click on create bucket

4. Now you can upload files and folders in to that bucket

Amazon s3 has 3 storage classes:

Versioning :

We may use versioning to keep multiple versions of an object in one bucket Why do we need multiple versions ? - Example - we put a image named "image" into the s3 bucket and created a copy of it in the same bucket. For both the images the name would be same but the version ID is different - This is called versioning.

By any case, if we lost that image , the other version of the image is there hence preventing data loss

• In case of s3 , by default version ID is disabled
• Versioning prevents overwriting or accidental deletion of data
• Get non concurrent version by specifying version ID - Basically ,The latest version of the data comes on the top . If we want to get particular version of the data , we can fetch it by specifying the version ID.

Cross region replication -

This allows to move data that is stored in a bucket in one region to another bucket that is stored in another region, By enabling it in the Management tab.

->Versioning is required , we cannot move the data with versioning suspended

->Here, we have a flexibility of changing the storage class of the object in the destination bucket

Life cycle Management -

We can change the life cycle(change in the storage class)of the objects in the bucket that is available under the Management tab

->It asks - which version to move , when to move , and when to expire that for all the objects in that bucket

S3 Transfer Acceleration :

• This sevice moves the files faster than snowball and snowmobile(Takes days to move)
• It enables fast, easy and secure transfers of files over longer distances( if the file is present in far away datacenter) between you and your client, with the help of cloud front
• Amazon cloud Front Edge Location -It is established in a location that is nearer to the client to cache the data . So that the response is given in a less time 

Some testcases:

• If versioning is not enabled , and we are upload the file file that already exists , the new file replaces the old one
• For cross region replication - versioning is required , we cannot move the data with versioning suspended

ARN - Amazon Resource Name

ACL - Access Control List 

Policy generator:

If we want to give the permissions of our own other than existing ACL's, we can create our own set of permissions with the help of policy generator Under permissions we can see this policy generator

Select policy type - Select the service for which you want to apply the policy

Effect - This tells the console whether is to allow a specific permision or to deny a specific permission

Principal - For want objects in the bucket we want to set permissions for, '*' for all the objects

Amazon Resource Name - copy the ARN of the bucket and paste here- at the end of the ARN -'/*' should be given, Eg: arn:aws:s3:::pujitha/*

copy the code and paste it in the policy generator page