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A user runs the command “dd if=/dev/zero of=/dev/xvdfbs=1M” on a fresh blank EBS volume attached to a Linux instance. Which of the below mentioned activities is the user performing with the command given above?
A. Creating a file system on the EBS volume
B. Mounting the device to the instance
C. Pre warming the EBS volume
D. Formatting the EBS volume
Correct Answer: C
Explanation/Reference:
Explanation:
When the user creates a new 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 blank volume attached with a Linux OS, the “dd” command is used to write to all the blocks on the device. In the command “dd if=/dev/zero of=/dev/xvdfbs=1M” the parameter “if=import file” should be set to one of the Linux virtual devices, such as /dev/zero. The “of=output file” parameter should be set to the drive that the user wishes to warm. The “bs” parameter sets the block size of the write operation; for optimal performance, this should be set to 1 MB.
