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Your department creates regular analytics reports from your company’s log files All log data is collected in
Amazon S3 and processed by daily Amazon Elastic MapReduce (EMR) jobs that generate daily PDF reports
and aggregated tables in CSV format for an Amazon Redshift data warehouse.
Your CFO requests that you optimize the cost structure for this system.
Which of the following alternatives will lower costs without compromising average performance of the system or
data integrity for the raw data?

Use reduced redundancy storage (RRS) for all data In S3. Use a combination of Spot Instances and
Reserved Instances for Amazon EMR jobs. Use Reserved Instances for Amazon Redshift.

Use reduced redundancy storage (RRS) for PDF and .csv data in S3. Add Spot Instances to EMR jobs. Use
Spot Instances for Amazon Redshift.

Use reduced redundancy storage (RRS) for PDF and .csv data In Amazon S3. Add Spot Instances to
Amazon EMR jobs. Use Reserved Instances for Amazon Redshift.

Use reduced redundancy storage (RRS) for all data in Amazon S3. Add Spot Instances to Amazon EMR
jobs. Use Reserved Instances for Amazon Redshift.

Using Reduced Redundancy Storage
Amazon S3 stores objects according to their storage class. It assigns the storage class to an object when it is
written to Amazon S3. You can assign objects a specific storage class (standard or reduced redundancy) only
when you write the objects to an Amazon S3 bucket or when you copy objects that are already stored in
Amazon S3. Standard is the default storage class. For information about storage classes, see Object Key and
In order to reduce storage costs, you can use reduced redundancy storage for noncritical, reproducible data at
lower levels of redundancy than Amazon S3 provides with standard storage. The lower level of redundancy
results in less durability and availability, but in many cases, the lower costs can make reduced redundancy
storage an acceptable storage solution. For example, it can be a cost-effective solution for sharing media
content that is durably stored elsewhere. It can also make sense if you are storing thumbnails and other resized
images that can be easily reproduced from an original image.
Reduced redundancy storage is designed to provide 99.99% durability of objects over a given year. This
durability level corresponds to an average annual expected loss of 0.01% of objects. For example, if you store
10,000 objects using the RRS option, you can, on average, expect to incur an annual loss of a single object per
year (0.01% of 10,000 objects).
This annual loss represents an expected average and does not guarantee the loss of less than 0.01% of
objects in a given year.
Reduced redundancy storage stores objects on multiple devices across multiple facilities, providing 400 times
the durability of a typical disk drive, but it does not replicate objects as many times as Amazon S3 standard
storage. In addition, reduced redundancy storage is designed to sustain the loss of data in a single facility.
If an object in reduced redundancy storage has been lost, Amazon S3 will return a 405 error on requests made
to that object. Amazon S3 also offers notifications for reduced redundancy storage object loss: you can
configure your bucket so that when Amazon S3 detects the loss of an RRS object, a notification will be sent
through Amazon Simple Notification Service (Amazon SNS). You can then replace the lost object. To enable
notifications, you can use the Amazon S3 console to set the Notifications property of your bucket.

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