LCA File Systems & Storage Management 5

Question 1

Which command creates a 2 GB sparse file named 'disk.img' using dd?

Accepted Answer

dd if=/dev/zero bs=1 count=0 seek=2G of=disk.img

Answer

Using seek=2G with count=0 creates a sparse file by placing the file pointer without writing zeros, consuming no actual disk blocks.

Question 2

What is the effect of running 'vgreduce vg0 /dev/sdb' without pvmove first?

Accepted Answer

Fails if /dev/sdb still holds active physical extents

Answer

vgreduce refuses to remove a PV that still contains allocated physical extents; pvmove must be run first.

Question 3

Which command mounts an ISO image file as a loopback device at /mnt/iso?

Accepted Answer

mount -o loop image.iso /mnt/iso

Answer

The -o loop option tells mount to use a loop device to mount the image file as if it were a block device.

Question 4

What does the XFS 'xfs_growfs' command do?

Accepted Answer

Expands a mounted XFS filesystem to fill available space on its underlying device

Answer

xfs_growfs can expand an XFS filesystem online (while mounted) to use newly added space on the underlying block device.

Question 5

Which command lists all open files on a specific mount point, useful before unmounting?

Accepted Answer

lsof +D /mnt/data

Answer

lsof +D recursively lists all open files under a directory, helping identify processes preventing unmount.

(LCA) Certified Linux Administrator Practice Test