A user runs the command “dd if=/dev/xvdf of=/dev/null bs=1M” on an EBS volume created from a snapshot
and attached to a Linux instance. Which of the below mentioned activities is the user performing with the step
given above?

A.
Pre warming the EBS volume

B.
Initiating the device to mount on the EBS volume

C.
Formatting the volume

D.
Copying the data from a snapshot to the device

Explanation:
When the user creates an EBS volume and is trying to access it for the first time it will encounter reduced IOPS
due to wiping or initiating of the block storage. To avoid this as well as achieve the best performance it is
required to pre warm the EBS volume. For a volume created from a snapshot and attached with a Linux OS,
the “dd” command pre warms the existing data on EBS and any restored snapshots of volumes that have been
previously fully pre warmed. This command maintains incremental snapshots; however, because this operation
is read-only, it does not pre warm unused space that has never been written to on the original volume. In the
command “dd if=/dev/xvdf of=/dev/null bs=1M” , the parameter “if=input file” should be set to the drive that the
user wishes to warm. The “of=output file” parameter should be set to the Linux null virtual device, /dev/null. The
“bs” parameter sets the block size of the read operation; for optimal performance, this should be set to 1 MB.