LPIC-2 Block Devices, Filesystems and Advanced Storage — 30 Questions

Question 1

An administrator is designing a high-availability storage solution using DRBD. The requirement is to have two nodes with synchronous replication and automatic failover in case of primary node failure. Which configuration best achieves this?

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

Accepted Answer

DRBD in Primary/Primary mode managed by Pacemaker cluster stack.. DRBD in Primary/Primary mode, managed by the Pacemaker cluster stack, provides synchronous replication and automatic failover. Pacemaker monitors node health and can promote the secondary node to primary automatically upon primary failure, meeting the high-availability requirement without manual intervention.

Answer

Export the DRBD block device via NFS and use a load balancer.

Answer

Primary/Secondary DRBD resource with manual failover using drbdadm.

Answer

DRBD with Heartbeat to automatically promote the secondary on primary failure.

Question 2

A filesystem is reported as 'read-only' after an unexpected power failure. Which command should be used to attempt repair without data loss?

Accepted Answer

fsck -n /dev/sda1. After an unexpected power failure, the filesystem may have been marked as needing a clean replay of its journal, but it is not necessarily corrupted. Running `fsck -n` performs a read-only check of the filesystem without making any changes, allowing you to assess the extent of damage or confirm that the journal replay is all that is needed. This avoids the risk of `fsck` making incorrect automatic repairs that could cause data loss, which is critical when the root cause is an unclean shutdown rather than structural corruption.

Answer

mount -o remount,rw /dev/sda1

Answer

fsck -y /dev/sda1

Answer

e2fsck -p /dev/sda1

Question 3

A Linux administrator is managing a database server running on CentOS 7 that uses ext4 filesystems on LVM. The server has three physical volumes: /dev/sda (200GB), /dev/sdb (200GB), and /dev/sdc (200GB) all in volume group 'vg_db'. The logical volume 'lv_data' (400GB) is used for database files. Recently, the DBA reports that database writes are slower than expected. Iostat shows high average wait times (>100ms) on /dev/sdc but normal on /dev/sda and /dev/sdb. The LVM stripes data across all three PVs with a stripe size of 64KB. Which action should the administrator take to improve performance?

Accepted Answer

Replace /dev/sdc with a new disk and restore the mirror or restripe.. The high average wait time on /dev/sdc indicates that this specific physical volume is a performance bottleneck, likely due to hardware failure or degradation. Since the logical volume 'lv_data' stripes data across all three PVs, the overall write performance is limited by the slowest device in the stripe set. Replacing /dev/sdc with a new disk and restoring the stripe (e.g., using pvmove to relocate extents and then replacing the device) eliminates the bottleneck and restores balanced I/O across all PVs.

Answer

Convert lv_data to linear mapping on /dev/sda and /dev/sdb only.

Answer

Increase the stripe size to 256KB to reduce I/O overhead.

Answer

Remove /dev/sdc from the volume group and reduce the stripe count to 2.

Question 4

A system administrator needs to create a new 500 MB ext4 filesystem on /dev/sdb1 and mount it persistently at /data. Which set of commands accomplishes this task?

Accepted Answer

mkfs.ext4 /dev/sdb1 && echo '/dev/sdb1 /data ext4 defaults 0 2' >> /etc/fstab && mount -a. It first creates an ext4 filesystem on /dev/sdb1 using mkfs.ext4, then appends a mount entry to /etc/fstab with the correct filesystem type (ext4) and mount point (/data), and finally runs mount -a to mount all filesystems from fstab, including the new one. This sequence ensures the filesystem is created, persistently configured, and immediately mounted.

Answer

mkfs -t ext4 /dev/sdb1 && mount /dev/sdb1 /data

Answer

blkid /dev/sdb1 && echo 'UUID=... /data ext4 defaults 0 2' >> /etc/fstab && mount -a

Answer

mkfs.xfs /dev/sdb1 && echo '/dev/sdb1 /data xfs defaults 0 2' >> /etc/fstab && mount -a

Question 5

Which TWO statements about LVM thin provisioning are correct?

Accepted Answer

It allows creating logical volumes that can be larger than the available physical storage.. Option B is correct because LVM thin provisioning uses over-provisioning: a thin logical volume can be created with a virtual size larger than the free space in its thin pool, and physical blocks are allocated only when data is actually written. Option E is correct because thin snapshots are copy-on-write and initially reference the same data blocks as the origin, so they consume almost no additional space until the origin or snapshot is modified. Option A is wrong because thin pools do not auto-extend at 80% usage; administrators must manually run lvextend (or configure monitoring/automation) to grow the pool. Option C is wrong because a thin pool can be extended with lvextend as long as free space exists in its volume group. Option D is wrong because thin provisioning is a device-mapper feature independent of the underlying storage type and works on HDDs, SSDs, and SAN LUNs alike.

Answer

Thin pools automatically extend when they reach 80% usage.

Answer

A thin pool cannot be extended once created.

Answer

It is only supported on SSDs.

Question 6

Match each LVM term to its definition.

Accepted Answer

Physical Volume (PV): A physical disk or partition that is initialized for use by LVM.. In LVM, Physical Volumes (PVs) are physical disks/partitions; Volume Groups (VGs) pool them; Logical Volumes (LVs) are created from VGs; Physical Extents (PEs) are the smallest allocation units on PVs. Common confusions involve swapping VG and LV definitions or confusing PE with LV.

Answer

Logical Volume (LV): The smallest allocatable unit of space on a Physical Volume.

Answer

Volume Group (VG): A virtual block device that can be used as a filesystem.

Question 7

An administrator needs to create an ext4 filesystem on /dev/sdb1 with a block size of 4096 bytes and reserve 2% of blocks for root. Which command accomplishes this?

Accepted Answer

mkfs.ext4 -b 4096 -m 2 /dev/sdb1. Mkfs.ext4 uses the `-b` option to specify the block size in bytes (4096) and `-m` to set the reserved blocks percentage for root (2%). The `-b` flag is the standard short form for block size in the mke2fs family of tools, and `-m` accepts a percentage value directly.

Answer

mkfs.ext4 --block-size 4096 -m 2 /dev/sdb1

Answer

mkfs.ext4 -B 4096 -m 2 /dev/sdb1

Answer

mkfs.ext4 -b 4096 -M 2 /dev/sdb1

Question 8

After adding a new LUN to an existing SAN, the administrator runs multipath -ll but sees the new LUN as 'failed'. The multipathd service is running. What is the most likely cause?

Accepted Answer

The new LUN has not been presented to the host from the SAN. When a new LUN appears as 'failed' in `multipath -ll` output, the most common cause is that the LUN has not been properly presented to the host from the SAN. Even if the multipathd service is running, multipathd can only manage devices that the SCSI layer has already discovered. If the SAN administrator has not zoned or masked the LUN to the host, the host's SCSI subsystem never sees the device, so multipathd reports it as 'failed' because it cannot find the underlying paths.

Answer

The multipathd daemon needs to be restarted

Answer

The /etc/multipath.conf needs to be edited to include the new LUN

Answer

The scsi device needs to be manually created with mknod

Question 9

An administrator needs to extend an ext4 filesystem on logical volume 'home' by 5 GB. The volume group 'vg' has free extents. Which sequence of commands is correct?

Accepted Answer

lvresize -L +5G /dev/vg/home; e2fsck -f /dev/vg/home; resize2fs /dev/vg/home. The correct sequence is to first extend the logical volume by the required size using `lvresize -L +5G` (or `lvextend`), optionally check the filesystem with `e2fsck -f`, and then resize the filesystem with `resize2fs`. This ensures the filesystem can utilize the newly allocated space. Option A is incorrect because it extends by all free extents, not exactly 5 GB. Option B reverses the order, which fails because `resize2fs` cannot extend beyond the current block device. Option C uses `mount -o remount`, which does not resize the filesystem.

Answer

lvextend -l +100%FREE /dev/vg/home; resize2fs /dev/vg/home

Answer

resize2fs /dev/vg/home; lvextend -L +5G /dev/vg/home

Answer

lvextend -L +5G /dev/vg/home; mount -o remount /dev/vg/home

Question 10

A system's root filesystem on /dev/sda1 is offline. The administrator boots into rescue mode and needs to check the filesystem integrity. Which command should be used first?

Accepted Answer

e2fsck -p /dev/sda1. `e2fsck -p` runs an automatic, non-interactive filesystem check on the ext2/ext3/ext4 filesystem, which is the safest first step when the root filesystem is offline and the administrator is in rescue mode. The `-p` flag automatically repairs any problems that can be safely fixed without user intervention, minimizing risk of further damage. This command is specifically designed for ext-family filesystems and is the recommended initial integrity check before attempting any manual repairs.

Answer

dumpe2fs /dev/sda1

Answer

fsck.ext4 -f /dev/sda1

Answer

fsck -N /dev/sda1

Question 11

Which command can be used to display all UUIDs of block devices that contain filesystems?

Accepted Answer

lsblk -f. Both `lsblk -f` and `blkid` can display UUIDs for block devices that contain filesystems. `lsblk -f` lists filesystem information (including UUIDs) in a tree format, while `blkid` directly queries block device metadata. Option A (lsblk -f) and Option C (blkid) are both correct. Option B is not a valid command but a phrase, and it incorrectly refers to itself. Option D (fdisk -l) does not show UUIDs.

Answer

both A and B

Answer

fdisk -l

Question 12

A storage administrator sees the following output from multipath -ll: 'dm-3 (3600605b0038f1f0019f1f7e00000000) size=10G features='0' hwhandler='0' wp=rw' but the paths are all 'failed'. The scsi devices are listed in /proc/scsi/scsi. What is the most likely cause?

Accepted Answer

The SAN fiber cables are disconnected. The output from multipath -ll shows the multipath device dm-3 with its WWID and size, but all paths are 'failed'. Since /proc/scsi/scsi lists the SCSI devices, the host bus adapters (HBAs) and drivers are functioning at the OS level. The most common cause for all paths to fail simultaneously is a physical connectivity issue, such as disconnected SAN fiber cables, which prevents the initiator from reaching the target LUNs.

Answer

The device mapper is not configured

Answer

The multipathd daemon is not running

Answer

The multipath configuration uses user_friendly_names but the bindings file is missing

Question 13

Which two commands display information about LVM physical volumes? (Choose two.)

Accepted Answer

pvs. Option A, pvs, is correct because it produces a concise, one-line-per-physical-volume report showing attributes such as PV name, volume group (VG), format, attributes (e.g., allocatable), physical size (PSize), physical free (PFree), and UUID. Option E, pvdisplay, is correct because it shows detailed information about each LVM physical volume, including PV name, VG name, PV size, allocatable status, PE size, total/free PE counts, and UUID. Option B, pvcreate, is incorrect because it initializes a block device as an LVM physical volume rather than displaying PV information. Option C, pvck, is incorrect because it checks and repairs LVM metadata consistency on physical volumes, not display them. Option D, pvscan, is incorrect because it scans block devices for LVM physical volumes and can update the LVM cache, but it is not primarily a command for displaying PV details.

Answer

pvcreate

Answer

pvck

Answer

pvscan

Question 14

Refer to the exhibit. The administrator wants to mount /dev/sdb1 at /data using its UUID. Which /etc/fstab entry is correct?

Accepted Answer

UUID=ijkl-9012 /data ext4 defaults 0 0. The administrator wants to mount /dev/sdb1 using its UUID, and the exhibit (not shown) indicates that the UUID of /dev/sdb1 is 'ijkl-9012'. The correct /etc/fstab syntax uses the 'UUID=' prefix followed by the actual UUID value, the mount point, filesystem type, options, dump, and pass fields. This ensures the filesystem is identified by its universally unique identifier, which remains stable even if the device name changes.

Answer

/dev/sdb1 /data ext4 defaults 0 0

Answer

PARTUUID=ijkl-9012 /data ext4 defaults 0 0

Answer

UUID=12345678-01 /data ext4 defaults 0 0

Question 15

Refer to the exhibit. A system administrator wants to replace disk sdb1 in the RAID1 array. After physically removing sdb, which sequence of commands should be used?

Accepted Answer

mdadm /dev/md0 --fail /dev/sdb1; mdadm /dev/md0 --remove /dev/sdb1; mdadm /dev/md0 --add /dev/sdd1; mdadm --manage /dev/md0 --run. After physically removing the failed disk (sdb), the administrator must first mark the device as failed using `--fail`, then remove it with `--remove`, add the new disk (sdd1) with `--add`, and finally run `--run` to ensure the array is activated if it was stopped or degraded. The `--run` flag is necessary because a RAID1 array with a missing device may not automatically start; this command forces the array to become active so the rebuild can begin. Note that the question does not involve filesystem extension; the focus is on the correct sequence for replacing a disk in a RAID array.

Answer

mdadm /dev/md0 --remove /dev/sdb1; mdadm /dev/md0 --add /dev/sdd1

Answer

mdadm /dev/md0 --fail /dev/sdb1; mdadm /dev/md0 --remove /dev/sdb1; mdadm /dev/md0 --add /dev/sdd1

Answer

mdadm /dev/md0 --fail /dev/sdb1; mdadm /dev/md0 --remove /dev/sdb1; mdadm --grow /dev/md0 --add /dev/sdd1; mdadm --manage /dev/md0 --run

Question 16

Which command can be used to create a swap partition on /dev/sdb1?

Accepted Answer

mkswap /dev/sdb1; swapon /dev/sdb1. B is correct because creating a swap partition requires two steps: first, `mkswap` initializes the partition as a swap area by writing a swap signature (UUID and superblock) to /dev/sdb1; second, `swapon` activates the swap space, making it available to the kernel for paging. Without `mkswap`, the partition lacks the necessary swap metadata and cannot be used.

Answer

swapcreate /dev/sdb1

Answer

swapon /dev/sdb1

Answer

mkfs.swap /dev/sdb1

Question 17

An administrator wants to convert an ext4 filesystem to Btrfs without losing data. Which procedure should be used?

Accepted Answer

btrfs-convert /dev/sda1. The correct procedure is to use `btrfs-convert /dev/sda1`, which is a dedicated tool that performs an in-place conversion of an existing ext2/3/4 filesystem to Btrfs while preserving all existing data. It works by creating a Btrfs filesystem that wraps the original ext4 data structures, then allowing a gradual migration to native Btrfs features via a background process.

Answer

mkfs.btrfs /dev/sda1

Answer

cp -a /mnt/ext4 /mnt/btrfs

Answer

btrfs device add /dev/sda1 /mnt

Question 18

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 19

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 20

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