LPIC-1 Devices, Filesystems and FHS Practice Test 4 — 15 Questions

Question 1

A company wants to migrate a database server from ext4 to XFS to support larger files and better scalability. The current data resides on a single partition /dev/sda1 mounted at /data. Which procedure ensures a successful migration with minimal downtime?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Add a new disk, create a partition with mkfs.xfs, mount it at /mnt, copy /data contents using cp -a, update /etc/fstab to use the new device, and remount.. It provides a safe, low-downtime migration path: create a new XFS filesystem on a separate disk, copy the existing data with `cp -a` to preserve permissions and metadata, update `/etc/fstab` to mount the new XFS device at `/data`, and remount. This avoids modifying the original ext4 partition and ensures the database files are intact on a supported filesystem.

Answer

Use dd if=/dev/sda1 of=/dev/sdb1 bs=4M to clone the partition, then change fstab to use /dev/sdb1.

Answer

Run tune2fs -O xfs /dev/sda1 to change the filesystem type.

Answer

Mount an NFS share, use rsync to copy data to the NFS mount, then unmount and reformat the original partition with XFS.

Question 2

A Linux system has a 500GB SSD. The administrator wants to partition it to support a web server with the following requirements: root (/) 20GB, swap 4GB, /var 50GB, /home 100GB, and the remaining for /srv. Which partitioning strategy is best practice according to the FHS and performance considerations?

Accepted Answer

Create separate partitions for root, swap, /var, /home, and /srv.. Creating separate partitions for root, swap, /var, /home, and /srv aligns with best practices for the Filesystem Hierarchy Standard (FHS) and performance isolation. This approach prevents one filesystem from exhausting space needed by another (e.g., runaway logs in /var cannot fill /home) and allows independent mount options (e.g., noexec on /home) and filesystem tuning for each mount point.

Answer

Use a single partition for root, but create separate partitions for /tmp, /var, /home, and /srv.

Answer

Create a single LVM volume group with logical volumes for each mount point.

Answer

Allocate one large partition for root and use bind mounts for /var, /home, and /srv.

Question 3

According to the Filesystem Hierarchy Standard (FHS), in which directory should third-party static libraries be installed?

Accepted Answer

/usr/local/lib. According to the Filesystem Hierarchy Standard (FHS), third-party static libraries should be installed in directories dedicated to locally-installed software. /usr/local/lib is for libraries that support site-specific software managed by the local administrator. /opt/lib is for libraries that are part of add-on application packages (such as those in /opt). These directories are intended for third-party static libraries that are not part of the core operating system's package management. /usr/lib (D) is reserved for libraries from the distribution's package manager, and /lib (A) is for libraries required for booting and core system functionality.

Answer

/lib

Answer

/usr/lib

Question 4

Which THREE directories under the root filesystem are typically used for variable data that changes frequently during system operation, according to FHS?

Accepted Answer

/var. According to the Filesystem Hierarchy Standard (FHS), /var (option B) is the primary directory for variable data files whose content is expected to change during normal system operation, such as logs, spool files, and databases. /run (option C) is also designated for variable runtime data, holding transient files like PID files and sockets that describe the system since boot. /tmp (option D) is used for temporary files that are variable in nature and may be cleared on reboot, fitting the definition of frequently changing data. In contrast, /usr (option A) contains static, shareable read-only data such as binaries and libraries, /opt (option E) is reserved for static add-on application software packages, and neither is intended for variable data.

Answer

/usr

Answer

/opt

Question 5

Which TWO utilities can be used to check and repair an XFS filesystem?

Accepted Answer

fsck. Option B (fsck) is correct because the generic fsck front-end can be invoked on an XFS filesystem; on modern systems fsck.xfs is a wrapper that simply calls xfs_repair when the filesystem is not mounted, so it can be used to check and repair XFS. Option C (xfs_repair) is correct because it is the native XFS utility specifically designed to check and repair XFS filesystems, typically run on an unmounted filesystem (or with -n for a read-only check). Option A (e2fsck) is incorrect because it is the ext2/ext3/ext4 filesystem checker and does not support XFS. Option D (xfs_check) is incorrect because it is a deprecated, read-only XFS consistency checker that was removed in favor of xfs_repair and cannot repair the filesystem. Option E (btrfs check) is incorrect because it is the checker for Btrfs filesystems, not XFS.

Answer

e2fsck

Answer

xfs_check

Answer

btrfs check

Question 6

You are the system administrator for a small business running a Red Hat Enterprise Linux 8 server that hosts a MySQL database and a web server. The server has two physical disks: a 240GB SSD (sda) with partitions sda1 (boot), sda2 (root), sda3 (swap), and a 1TB HDD (sdb) with a single partition sdb1 mounted at /var/lib/mysql. The server has been running for months without issues. However, this morning you receive alerts that the MySQL database is not accepting new connections. You log in and find that the /var filesystem is 100% full. You check the disk usage and see that /var/lib/mysql uses 90% of the space, but there are also large log files in /var/log/httpd. To free up space immediately and restore database service while planning a permanent solution, you decide to compress old log files and move some database archives to a backup server. After compressing several log files with gzip, the available space increases by only a few MB. You then delete some old database backups from /var/lib/mysql/backup, but the space usage shown by df remains unchanged. What is the most likely cause of this behavior?

Accepted Answer

Some processes have open file handles to the deleted files, preventing the space from being released.. When a file is deleted but still held open by a running process (e.g., the MySQL daemon or httpd), the filesystem does not release the disk space until all file handles are closed. In this scenario, the large log files in /var/log/httpd were compressed with gzip, but the original uncompressed files may still be open by the web server process, so deleting them (or the old database backups) does not free space until the process is restarted or the handles are released. This explains why df still shows 100% usage despite the deletions.

Answer

The disk quota for the mysql user is exceeded, so deletions do not reduce usage.

Answer

The SSD is not TRIM-enabled, so deleted blocks are not reclaimed.

Answer

The filesystem was remounted read-only due to errors, so deletions are not permanent.

Question 7

You are a Linux administrator for a large e-commerce company. The company's application server runs Ubuntu 22.04 and uses a Btrfs filesystem for the /srv/app partition to take advantage of snapshots and compression. During a routine maintenance window, you create a snapshot of the /srv/app subvolume using 'btrfs subvolume snapshot /srv/app /srv/app_snapshot'. Later, you need to roll back to the snapshot because of a failed application update. You attempt to delete the original subvolume with 'btrfs subvolume delete /srv/app', but the command fails with the error: 'ERROR: cannot delete '/srv/app': Device or resource busy'. You check that no processes are using the directory with lsof, and it shows no open files. The /srv/app subvolume is the default subvolume and is mounted via fstab with the option 'subvol=/' (the root of the Btrfs filesystem). What is the most likely reason for the deletion failure, and how should you proceed?

Accepted Answer

The subvolume is the default subvolume (ID 5) and cannot be deleted while it is the mounted root; use 'btrfs subvolume set-default <new_subvol_id> /srv/app', then unmount and remount with the new default subvolume, then delete the old subvolume.. The error occurs because the subvolume at /srv/app is the default subvolume (ID 5) of the Btrfs filesystem, and it is currently mounted as the root of the filesystem via the 'subvol=/' mount option. A default subvolume cannot be deleted while it is mounted because the kernel treats it as the top-level volume. To delete it, you must first set a different subvolume as the default using 'btrfs subvolume set-default', then unmount and remount the filesystem with the new default, after which the original subvolume can be safely deleted.

Answer

The subvolume is read-only; change it to read-write with 'btrfs property set -f /srv/app ro false'.

Answer

You cannot delete the subvolume because it is the default subvolume; you must first delete the snapshot and then recreate the original.

Answer

The Btrfs kernel module has a readahead lock on the subvolume; wait for it to expire or reboot.

Question 8

You are a junior system administrator tasked with adding a new 500GB HDD to a Debian 11 server that will be used for backup storage. The server currently has a 120GB SSD with two partitions: sda1 (boot) and sda2 (root). You have physically installed the HDD and it is recognized as /dev/sdb. You need to partition the disk with a single partition covering the entire disk, format it as ext4, and ensure it is automatically mounted at /backup at boot time. Which sequence of commands should you execute to accomplish this?

Accepted Answer

sudo parted /dev/sdb mklabel gpt && sudo parted /dev/sdb mkpart primary ext4 0% 100% && sudo mkfs.ext4 /dev/sdb1 && echo '/dev/sdb1 /backup ext4 defaults 0 2' | sudo tee -a /etc/fstab && sudo mount -a. It first creates a GPT partition table on /dev/sdb with parted, then creates a single primary partition spanning the entire disk, formats that partition (not the raw disk) as ext4, adds an fstab entry for automatic mounting at /backup, and finally mounts all filesystems. This sequence ensures the disk is properly partitioned, formatted, and configured for persistent boot-time mounting.

Answer

sudo mkfs.ext4 /dev/sdb1 && echo '/dev/sdb1 /backup ext4 defaults 0 2' | sudo tee -a /etc/fstab && sudo mount -a

Answer

sudo mkfs.ext4 /dev/sdb && echo '/dev/sdb /backup ext4 defaults 0 2' | sudo tee -a /etc/fstab && sudo mount -a

Answer

sudo fdisk /dev/sdb (create partition) && sudo mkswap /dev/sdb1 && echo '/dev/sdb1 /backup ext4 defaults 0 2' | sudo tee -a /etc/fstab && sudo mount -a

Question 9

You manage a CentOS 7 server that runs a critical application storing data on an XFS filesystem mounted at /data. The server experiences an unexpected power outage. After rebooting, the application fails to start, and you suspect filesystem corruption. You boot into single-user mode and attempt to mount /data, but the mount fails with an error: 'mount: /dev/sdb1: can't read superblock'. You run 'xfs_repair -n /dev/sdb1' and it reports the log is dirty and must be replayed or the filesystem repaired with the -L option (force log zeroing). You want to recover the filesystem with minimal data loss. Which action should you take?

Accepted Answer

Run 'xfs_repair -L /dev/sdb1' to force log replay and repair.. Xfs_repair -L /dev/sdb1 forces the log to be zeroed (cleared) and then performs a full filesystem check and repair. This is necessary when the log is dirty and cannot be replayed normally due to corruption, such as after an unclean shutdown. The -L option is the standard recovery method for XFS when the log is damaged, and it minimizes data loss by only discarding the log (which contains metadata changes that were not yet written to disk) while preserving the rest of the filesystem data.

Answer

Mount the filesystem with the 'norecovery' option to bypass the log and then attempt to repair.

Answer

Run 'fsck -y /dev/sdb1' to automatically repair.

Answer

Run 'xfs_admin -U generate /dev/sdb1' to generate a new UUID and then mount.

Question 10

A user reports that a USB drive (device /dev/sdc1) is not automatically mounted at boot. The output of 'blkid' and the relevant line in /etc/fstab are shown in the exhibit. What is the most likely cause of the failure?

Accepted Answer

The UUID in /etc/fstab does not match the device's UUID.. The most likely cause is that the UUID in /etc/fstab does not match the device's UUID. The blkid output shows the actual UUID of /dev/sdc1, and if the fstab entry has a different UUID (or uses an incorrect one), the system will fail to mount the device at boot because it cannot find a matching block device by UUID.

Answer

The device /dev/sdc1 does not exist.

Answer

The mount point /media/usb does not exist.

Answer

The filesystem is corrupted and requires fsck.

Answer

The filesystem type is incorrectly specified as vfat.

Question 11

According to the Filesystem Hierarchy Standard (FHS), which TWO directories are intended for variable data that persists across system reboots? (Choose two.)

Accepted Answer

/var. According to the Filesystem Hierarchy Standard (FHS), /var is the designated directory for variable data such as logs, spools, and databases that persist across reboots. /run is intended for runtime variable data and is typically cleared on boot, so it does not persist. Therefore, only /var is correct.

Answer

/run

Answer

/opt

Answer

/usr/local

Answer

/tmp

Question 12

An administrator is configuring a new server with two SATA disks. The first disk (/dev/sda) holds the root filesystem. The second disk (/dev/sdb) is intended to provide additional storage for user home directories. The administrator partitions /dev/sdb using 'fdisk' to create a single partition /dev/sdb1, formats it with 'mkfs.ext4' and adds the following line to /etc/fstab: '/dev/sdb1 /home ext4 defaults 0 2'. After rebooting, the /home directory is empty and the command 'df -h' does not show /dev/sdb1. However, running 'mount /dev/sdb1 /home' manually works perfectly. The disk is not listed in 'cat /proc/mounts' before the manual mount. What is the most likely cause of this issue?

Accepted Answer

The filesystem on /dev/sdb1 has errors and needs to be checked with fsck before mounting.. The filesystem on /dev/sdb1 has errors that prevent it from being mounted automatically at boot. The 'mount -a' command (run during boot) will skip filesystems that fail a pre-mount check, but a manual mount with 'mount /dev/sdb1 /home' will still succeed if the errors are not critical. The '0 2' in the fstab entry specifies that the filesystem should be checked by fsck on boot; if fsck finds errors, the mount is aborted to avoid data corruption.

Answer

The fstab entry is missing the _netdev option, which is required for local SATA disks.

Answer

The /home directory is not empty and contains files that conflict with the mount.

Answer

The fstab entry uses the device file /dev/sdb1 instead of the UUID.

Question 13

Refer to the exhibit. After adding a new disk to the system, the device /dev/sdb appears. However, the administrator cannot create partitions on /dev/sdb using fdisk. What is the most likely reason?

Accepted Answer

The disk is currently in use as a physical volume for LVM.. When a disk is in use as a physical volume (PV) for LVM, it is already claimed by the LVM subsystem. The `fdisk` utility cannot modify the partition table of a disk that is part of an LVM volume group because the kernel holds the device open and LVM metadata occupies the disk. The administrator must first remove the disk from LVM using `pvremove` before partitioning.

Answer

The disk is mounted and cannot be partitioned.

Answer

The disk does not have a valid partition table.

Answer

The kernel does not support the disk's interface.

Question 14

Refer to the exhibit. The system administrator wants to ensure the /data filesystem is mounted only if it is available at boot time, and if not, the system should continue to boot without error. Which change should be made to the /etc/fstab entry for /data?

Accepted Answer

Add the 'nofail' option and set the last field to 0. The 'nofail' mount option tells systemd that if the filesystem fails to mount at boot, the boot process should continue without error. Setting the last field (fs_passno) to 0 disables filesystem checks, which is appropriate for a non-critical filesystem that may not be present. This combination ensures the system boots normally even if /data is unavailable.

Answer

Change the mount point to /mnt/data

Answer

Change the filesystem type to auto

Answer

Add the 'noauto' option

Question 15

Refer to the exhibit. The root filesystem is at 95% capacity. Which option will free space on the root filesystem?

Accepted Answer

Move /var/log to /mnt/backup and create a symlink. Moving the /var/log directory to a separate partition or filesystem (e.g., /mnt/backup) and creating a symbolic link from /var/log to the new location frees space on the root filesystem without losing log data. This approach preserves the filesystem hierarchy and allows logs to continue growing on a different volume, preventing the root filesystem from filling up.

Answer

Resize /dev/sda1 using resize2fs

Answer

Delete all files in /var/log

Answer

Move /home to /mnt/backup and create a symlink