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.