LPIC-2 Block Devices, Filesystems and Advanced Storage Practice Test 3 — 15 Questions

Question 1

A filesystem check on an XFS filesystem reports corruption. What is the recommended way to repair it?

Accepted Answer

Run xfs_repair -n first, then unmount and repair.. The recommended procedure for repairing a corrupted XFS filesystem is to first run `xfs_repair -n` in dry-run mode to assess the damage without making changes, then unmount the filesystem and run `xfs_repair` to perform the actual repair. XFS does not support online repair; the filesystem must be unmounted for write operations to avoid further corruption.

Answer

Run xfs_check on the mounted filesystem.

Answer

Run xfs_repair on the unmounted filesystem.

Answer

Run fsck -t xfs on the mounted filesystem.

Question 2

Which of the following is the primary configuration file for the udev device manager?

Accepted Answer

/etc/udev/udev.conf. The primary configuration file for the udev device manager is /etc/udev/udev.conf. This file sets global parameters such as the device timeout, logging priority, and the default permissions for device nodes. While custom rules are placed in /etc/udev/rules.d/, the main configuration file that controls udev's behavior is udev.conf.

Answer

/etc/udev/rules.d/

Answer

/lib/udev/rules.d/

Answer

/etc/udev/rules.d/

Question 3

An administrator needs to configure iSCSI multipathing. After setting up two paths, which command should be used to verify the multipath topology?

Accepted Answer

multipath -l. The `multipath -l` command displays the current multipath topology, showing the aggregated device mapper (dm) devices, their underlying paths, and their status (active/passive or active/active). This is the standard tool for verifying multipath configuration after setting up iSCSI paths, as it reads the multipathd state and presents a human-readable map of the multipath devices.

Answer

lsscsi

Answer

dmsetup ls

Answer

iscsiadm -m session -P 3

Question 4

A filesystem created with mkfs.ext4 on /dev/sda1 has a reserved block count of 5%. How can the administrator reduce it to 1% without reformatting?

Accepted Answer

tune2fs -m 1 /dev/sda1. The `-m` option of tune2fs sets the reserved block percentage for the filesystem. Since the question asks to reduce the reserved block count from 5% to 1% without reformatting, `tune2fs -m 1 /dev/sda1` correctly adjusts the reserved blocks percentage to 1% on the existing ext4 filesystem.

Answer

tune2fs -r 1 /dev/sda1

Answer

dumpe2fs -r 1 /dev/sda1

Answer

resize2fs -r 1 /dev/sda1

Question 5

Which file contains the filesystem table that is read during system boot to mount filesystems?

Accepted Answer

/etc/fstab. /etc/fstab is the filesystem table file that is read by the system during boot (via mount -a or systemd-fstab-generator) to automatically mount filesystems. It contains entries specifying devices, mount points, filesystem types, mount options, dump and pass fields, and is the standard configuration file for static filesystem mounting.

Answer

/etc/mtab

Answer

/proc/mounts

Answer

/etc/mounts

Question 6

An administrator wants to create a thin provisioned LVM pool and a thin volume. Which sequence of commands is correct?

Accepted Answer

lvcreate -L 10G --thinpool vg/pool; lvcreate -V 5G --thin vg/pool/thinvol. It uses the correct LVM commands to create a thin provisioned pool and a thin volume. The first command, `lvcreate -L 10G --thinpool vg/pool`, creates a thin pool named 'pool' in volume group 'vg' with a 10G metadata and data area. The second command, `lvcreate -V 5G --thin vg/pool/thinvol`, creates a thin volume named 'thinvol' within that pool, specifying the virtual size with `-V`. The `--thinpool` and `--thin` flags are the proper LVM2 syntax for thin provisioning.

Answer

lvcreate -L 10G -T vg/pool; lvcreate -V 5G -T vg/pool/thinvol

Answer

lvcreate -L 10G -T vg/pool; lvcreate -n thinvol -V 5G vg/pool

Answer

lvcreate -L 10G -T vg/pool; lvcreate -V 5G -n thinvol vg/pool

Question 7

Which TWO commands display UUIDs of block devices? (Select TWO)

Accepted Answer

lsblk -o UUID. B is correct because `lsblk -o UUID` explicitly lists the UUID column for all block devices, showing the filesystem UUIDs. D is correct because `blkid` is the dedicated command to display block device attributes, including UUIDs, by reading the udev database or directly probing the device.

Answer

parted /dev/sda print

Answer

udevadm info --query=all --name=/dev/sda

Answer

fdisk -l

Question 8

Which THREE of the following are correct statements about LVM thin provisioning? (Select THREE)

Accepted Answer

Snapshots of thin volumes use the same pool.. LVM thin provisioning uses a shared thin pool to store data for all thin volumes and their snapshots. When a snapshot of a thin volume is created, it does not allocate separate physical storage; instead, it references the same thin pool, allowing efficient space usage and copy-on-write semantics.

Answer

A thin pool can be resized smaller without data loss.

Answer

Thin volumes must be created before the thin pool.

Question 9

Which THREE of the following are correct about RAID 1 in mdadm? (Select THREE)

Accepted Answer

It can have a hot spare.. RAID 1 in mdadm provides mirroring, where data is written identically to two or more disks. A hot spare is supported: if a disk fails, mdadm automatically rebuilds the mirror onto the spare. This requires at least 2 disks to form the mirror.

Answer

It provides striping.

Answer

It uses a bitmap for resync.

Question 10

An administrator runs the command shown. However, when a user tries to execute a binary from /mnt/tmp, it fails with 'Permission denied'. What is the most likely cause?

Accepted Answer

The noexec mount option prevents execution.. The `noexec` mount option explicitly prevents execution of any binaries on the filesystem, regardless of their permission bits. When a filesystem is mounted with `noexec`, the kernel will refuse to execute any file on that mount point, returning 'Permission denied' even if the file has execute permissions set. This is the most likely cause because the administrator's command likely mounted `/mnt/tmp` with `noexec` (e.g., via `mount -o noexec` or a default mount option).

Answer

The binary is not executable.

Answer

The tmpfs filesystem does not support execution.

Answer

The nosuid option prevents setuid binaries.

Question 11

An administrator observes that only one path is shown as active for mpathb. What is the most likely cause?

Accepted Answer

The blacklist rule excludes the other path.. When only one path is active for a multipath device (mpathb), the most likely cause is that the other path is being excluded by a blacklist rule in the multipath configuration. The blacklist can filter out devices based on WWID, device name, or vendor/product, preventing them from being aggregated into the multipath map. This results in the path being visible to the system but not used by multipathd.

Answer

The find_multipaths setting is incorrect.

Answer

The SCSI devices are not properly connected.

Answer

The multipathd service is not running.

Question 12

A company runs a database server on Linux with a 4-disk RAID 10 array using mdadm. The server recently experienced a power outage. After reboot, the array is not assembling automatically. The administrator runs `mdadm --assemble --scan` and it fails with a message: 'mdadm: /dev/md0 has been found but is not a valid md superblock.' The administrator checks /proc/mdstat and sees no arrays. The disks /dev/sda, /dev/sdb, /dev/sdc, /dev/sdd are present. Running `mdadm --examine /dev/sda` shows no md superblock, but the disk contains data partitions. The administrator suspects that the superblock may be corrupted or that the disks were accidentally overwritten. The administrator has documentation that the array was created with the following parameters: RAID level 10, 4 disks, chunk size 512 KiB, metadata 1.2. What is the best course of action to recover the array?

Accepted Answer

Use `mdadm --create --level=10 --raid-devices=4 --chunk=512 --metadata=1.2 --assume-clean /dev/md0 /dev/sda /dev/sdb /dev/sdc /dev/sdd` and then mount.. When the md superblock is missing or corrupted on all disks (as confirmed by `mdadm --examine` showing no superblock), the only way to recover the array is to recreate it with `--assume-clean`. This tells mdadm to trust that the data on the disks is already in a consistent RAID 10 layout without performing an initial resync, which would overwrite the existing data. The parameters must exactly match the original creation (RAID 10, 4 disks, chunk 512 KiB, metadata 1.2) to reconstruct the correct data mapping.

Answer

Use `mdadm --create --level=10 --raid-devices=4 --chunk=512 --metadata=1.2 /dev/md0 /dev/sda /dev/sdb /dev/sdc /dev/sdd` without --assume-clean and then run fsck.

Answer

Run `mdadm --examine --scan` to probe for superblocks on all disks, then attempt recovery with --super-minor or --uuid.

Answer

Use `dd` to backup each disk's first few sectors, then use a data recovery tool.

Question 13

A server running Linux with an ext4 filesystem on /dev/sda1 has experienced an unexpected power loss due to a faulty power supply. After replacing the power supply and rebooting, the system fails to mount /dev/sda1 with an error message indicating 'wrong superblock magic number' or 'superblock corrupted'. The administrator recalls that ext4 filesystems have backup superblocks created during mkfs. Using the command 'dumpe2fs /dev/sda1 | grep -i backup' is not possible because the device is not mountable. However, the administrator remembers that for this specific filesystem, a backup superblock is located at block offset 32768 based on the output of 'mke2fs -n' from the original creation. What is the correct course of action to recover the filesystem and mount it?

Accepted Answer

Run `fsck.ext4 -b 32768 /dev/sda1` to restore the superblock, then mount the filesystem.. `fsck.ext4 -b 32768` instructs the filesystem check utility to use the backup superblock located at block offset 32768, which is a known backup location for ext4 filesystems created with default settings. This allows `fsck` to read a valid superblock, repair the primary superblock, and make the filesystem mountable again without data loss.

Answer

Run `e2fsck -fy /dev/sda1` to force a filesystem check.

Answer

Run `dd if=/dev/zero of=/dev/sda1 bs=4k count=1` to zero the superblock, then create a new filesystem with mkfs.ext4.

Answer

Run `tune2fs -j /dev/sda1` to add a journal to the filesystem.

Question 14

An organization runs a critical application on a Linux server that stores its data on a 500GB LVM logical volume named /dev/vg_data/lv_app. The application must remain operational with minimal disruption, so unmounting the volume is not acceptable. The administrator needs to create a full backup of the logical volume to an external 1TB USB drive attached via eSATA. The backup must capture a point-in-time consistent state of the filesystem. The logical volume is formatted with XFS. Which of the following procedures best achieves this goal while minimizing downtime?

Accepted Answer

Create an LVM snapshot volume of /dev/vg_data/lv_app, mount the snapshot to a temporary directory, and use rsync to copy the data to the USB drive.. It uses an LVM snapshot to capture a point-in-time consistent state of the XFS filesystem without unmounting the original volume. The snapshot is mounted read-only, and rsync copies the data to the USB drive, ensuring minimal disruption to the running application. This approach leverages LVM's copy-on-write mechanism to freeze the filesystem state at the snapshot creation moment.

Answer

Unmount the logical volume, use tar to create an archive on the USB drive, then remount the volume.

Answer

Use dd to clone the logical volume directly to the USB drive while the volume is mounted.

Answer

Create an LVM snapshot volume and then use cp -a to copy the snapshot volume's contents directly without mounting.

Question 15

A system administrator needs to create a RAID 10 array using four disks: /dev/sdb, /dev/sdc, /dev/sdd, /dev/sde. Which TWO commands correctly achieve this?

Accepted Answer

mdadm --create /dev/md0 --level=10 --raid-devices=4 /dev/sdb /dev/sdc /dev/sdd /dev/sde. `--level=10` is the accepted syntax for RAID 10 in mdadm, and specifying `--raid-devices=4` with all four disks creates a RAID 10 array (a stripe of mirrors) directly. Option C is also correct because `--level=raid10` is an alternative valid syntax that mdadm accepts for the same RAID level.

Answer

mdadm --create /dev/md0 --level=1 --raid-devices=4 /dev/sdb /dev/sdc /dev/sdd /dev/sde

Answer

mdadm --create /dev/md0 --level=0 --raid-devices=2 /dev/sdb /dev/sdc --add /dev/md1

Answer

mdadm --create /dev/md0 --level=10 --raid-devices=2 /dev/sdb /dev/sdc