Linux Advanced File System and Storage 3

Question 1

Which command is used to resize an ext4 filesystem online (while mounted)?

Accepted Answer

resize2fs

Answer

resize2fs can resize ext2/3/4 filesystems; when the filesystem is mounted and the kernel supports it, online growing is possible.

Question 2

What does the 'dm-crypt' subsystem provide in Linux?

Accepted Answer

Transparent block-level encryption via the device mapper

Answer

dm-crypt is a Linux kernel device mapper target that provides transparent encryption of block devices using the kernel crypto API.

Question 3

What is the function of the 'fstrim' command?

Accepted Answer

Send TRIM/discard commands to an SSD to free unused blocks

Answer

fstrim issues TRIM commands to SSDs for all unused blocks in a mounted filesystem, helping maintain SSD performance and longevity.

Question 4

In Btrfs, what command creates a read-write snapshot of a subvolume?

Accepted Answer

btrfs subvolume snapshot

Answer

btrfs subvolume snapshot creates a snapshot of a subvolume; by default it is read-write unless the -r flag is passed.

Question 5

Which file in /proc provides real-time information about mounted filesystems and their usage?

Accepted Answer

/proc/mounts

Answer

/proc/mounts lists all currently mounted filesystems with their options, similar to /etc/mtab but always up to date.

Linux Practice Test