LFCS Storage Management Practice Test 4 — 15 Questions

Question 1

A storage administrator is setting up a new filesystem on a logical volume and wants to minimize metadata overhead for a workload that stores millions of very small files. Which TWO mkfs options for XFS should be used to reduce the inode size and increase the number of inodes available for this workload? (Choose two.)

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

Accepted Answer

-i maxpct=10. XFS inode size is controlled by the -i size= option, and the percentage of space reserved for inodes is set with -i maxpct=. Reducing the inode size to 256 bytes and capping inode space at 10 percent both help accommodate millions of tiny files without wasting metadata space. Directory block size, log size, and allocation group count affect other aspects of filesystem behavior and do not reduce inode overhead.

Answer

-d agcount=32

Answer

-n size=4096

Answer

-l size=128m

Question 2

A server has a swap partition /dev/sda2 that is too small. The administrator wants to add a 4 GiB swap file /swapfile on the root filesystem and enable it immediately and persistently. Which sequence of commands correctly creates and activates the swap file?

Accepted Answer

dd if=/dev/zero of=/swapfile bs=1M count=4096; chmod 600 /swapfile; mkswap /swapfile; swapon /swapfile. The correct procedure is to create a file of the desired size with dd, restrict permissions with chmod 600, initialize it with mkswap, and enable it with swapon. The fallocate method can be faster but may produce a file that swapon rejects due to unwritten extents, and it omits the permission change. The partition-based option does not create a file. The dd sequence with chmod is the reliable standard.

Answer

fallocate -l 4G /swapfile; mkswap /swapfile; swapon /swapfile

Answer

mkswap /dev/sda3; swapon /dev/sda3

Answer

touch /swapfile; dd if=/dev/zero of=/swapfile bs=1M count=4096; mkswap /swapfile; swapon /swapfile

Question 3

A system administrator is configuring a new server and needs to set up swap space. The server has a single disk with a large unused partition /dev/sda3. The administrator wants to use this partition as swap. Which two commands are required to activate /dev/sda3 as swap space immediately and ensure it is available after reboot? (Choose two.)

Accepted Answer

mkswap /dev/sda3. To set up a swap partition, it must first be initialized with mkswap to write the swap signature. Then swapon activates it for immediate use. To ensure the swap is enabled at boot, an entry must be added to /etc/fstab, but the question asks for the commands to activate it immediately and ensure availability after reboot; mkswap and swapon are the core commands, with fstab being a configuration step rather than a command. Therefore, mkswap and swapon are the two required commands.

Answer

mkfs.ext4 /dev/sda3

Answer

swapoff /dev/sda3

Answer

fdisk /dev/sda3

Question 4

A server has two disks, /dev/sda and /dev/sdb, each 500 GB. An administrator wants to combine them into a single 1 TB usable volume that can tolerate the loss of one disk, and also provide a write cache for performance. Which mdadm command creates the required array?

Accepted Answer

mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda /dev/sdb. RAID 1 mirrors two devices, delivering 500 GB usable with tolerance for one failed disk, and it is the only syntactically valid mdadm creation among the choices for two disks. RAID 0 meets capacity but offers no redundancy, RAID 5 cannot run on two members, and RAID 10 requires four devices, so none of those satisfy the fault-tolerance requirement here.

Answer

mdadm --build /dev/md0 --level=10 --raid-devices=2 /dev/sda /dev/sdb

Answer

mdadm --create /dev/md0 --level=0 --raid-devices=2 /dev/sda /dev/sdb

Answer

mdadm --create /dev/md0 --level=5 --raid-devices=2 /dev/sda /dev/sdb

Question 5

A system administrator needs to create a new 2 GiB swap file at /swapfile on a server running Ubuntu 22.04, and ensure it is activated immediately and persistently across reboots. Which sequence of commands accomplishes this?

Accepted Answer

dd if=/dev/zero of=/swapfile bs=1M count=2048; chmod 600 /swapfile; mkswap /swapfile; swapon /swapfile; echo '/swapfile none swap sw 0 0' >> /etc/fstab. The correct sequence uses dd to create a fully allocated 2 GiB file, sets permissions to 600, formats it with mkswap, activates it with swapon, and adds an fstab entry with 'none' as the mount point and 'sw' as the options. This ensures the swap file is secure and persistent.

Answer

fallocate -l 2G /swapfile; chmod 600 /swapfile; mkswap /swapfile; swapon /swapfile; echo '/swapfile swap swap defaults 0 0' >> /etc/fstab

Answer

truncate -s 2G /swapfile; chmod 600 /swapfile; mkswap /swapfile; swapon /swapfile; echo '/swapfile none swap sw 0 0' >> /etc/fstab

Answer

dd if=/dev/zero of=/swapfile bs=1M count=2048; mkswap /swapfile; swapon /swapfile; echo '/swapfile none swap sw 0 0' >> /etc/fstab

Question 6

An administrator needs to create a new 10 GB logical volume named lv_web in an existing volume group vg_app, and then format it with ext4 and mount it persistently at /var/www. The volume group has 15 GB of free space. Which sequence of commands will accomplish this?

Accepted Answer

lvcreate -L 10G -n lv_web vg_app; mkfs.ext4 /dev/vg_app/lv_web; mount /dev/vg_app/lv_web /var/www; echo '/dev/vg_app/lv_web /var/www ext4 defaults 0 0' >> /etc/fstab. The correct sequence must create a 10 GB logical volume, format it with ext4, mount it, and add an fstab entry for persistence. lvcreate -L 10G -n lv_web vg_app creates the LV with the exact size. mkfs.ext4 formats it. The mount command mounts it temporarily, and the echo command appends the correct fstab entry. The other options either use incorrect sizing or introduce unnecessary complexity.

Answer

lvcreate -L 10G -n lv_web vg_app; mkfs.ext4 /dev/vg_app/lv_web; echo '/dev/vg_app/lv_web /var/www ext4 defaults 0 0' >> /etc/fstab; mount -a

Answer

lvcreate -l 100%FREE -n lv_web vg_app; mkfs.ext4 /dev/vg_app/lv_web; mount /dev/vg_app/lv_web /var/www; echo '/dev/vg_app/lv_web /var/www ext4 defaults 0 0' >> /etc/fstab

Answer

lvcreate -L 10G -n lv_web vg_app; mkfs.ext4 /dev/mapper/vg_app-lv_web; mount /dev/mapper/vg_app-lv_web /var/www; echo '/dev/mapper/vg_app-lv_web /var/www ext4 defaults 0 0' >> /etc/fstab

Question 7

A Linux server has a RAID 1 array created with mdadm on /dev/md0, using /dev/sdb1 and /dev/sdc1. The administrator needs to replace the failed disk /dev/sdb with a new disk /dev/sdd. After physically installing /dev/sdd, which command correctly adds the new disk to the array?

Accepted Answer

sfdisk -d /dev/sdc | sfdisk /dev/sdd; mdadm --manage /dev/md0 --add /dev/sdd1. To replace a failed disk in a RAID 1 array, you must first ensure the new disk has a partition table matching the other member. Copying the partition table from the surviving disk with sfdisk, then adding the new partition with mdadm --manage --add, is the correct approach. The array will then rebuild onto the new disk.

Answer

mdadm --add /dev/md0 /dev/sdd1

Answer

mdadm --manage /dev/md0 --add /dev/sdd1

Answer

mdadm --grow /dev/md0 --add /dev/sdd

Question 8

Which command can be used to display the UUID of a filesystem on /dev/sdb1?

Accepted Answer

blkid /dev/sdb1. The blkid command is specifically designed to locate and print block device attributes, including the UUID and filesystem type. When run against a device like /dev/sdb1, it queries the kernel's device mapper and reads the filesystem superblock to extract the universally unique identifier (UUID). This is the most direct and reliable method for displaying a filesystem's UUID.

Answer

tune2fs -l /dev/sdb1

Answer

df -h /dev/sdb1

Answer

lsblk /dev/sdb1

Question 9

An administrator needs to mount an XFS filesystem with options to optimize for a database workload. Which mount option would reduce metadata updates to improve performance?

Accepted Answer

noatime. The `noatime` mount option disables updates to the inode access time (atime) on every file read. For database workloads, this eliminates a significant source of metadata write I/O, reducing disk contention and improving overall performance by avoiding unnecessary journal updates on XFS.

Answer

noexec

Answer

nodiratime

Answer

relatime

Question 10

A system administrator notices that a new 500GB SSD (/dev/sdb) is not being recognized by the system after installation. The server uses UEFI and GPT partitioning. Which command should the administrator run first to verify that the disk is detected by the kernel?

Accepted Answer

lsblk. The `lsblk` command lists all block devices recognized by the kernel, including those without a filesystem or partition table. Since the disk is new and not yet partitioned, `lsblk` will show it if the kernel has detected it, making it the correct first diagnostic step.

Answer

fdisk -l /dev/sdb

Answer

cat /proc/cpuinfo

Answer

lsusb

Question 11

Which TWO commands can be used to mount a filesystem on /dev/sdb1 to /mnt/data?

Accepted Answer

mount /dev/sdb1 /mnt/data. Option B is correct because the standard mount syntax is `mount `, so `mount /dev/sdb1 /mnt/data` mounts the block device /dev/sdb1 onto the existing directory /mnt/data. Option C is also correct because adding `-t ext4` explicitly specifies the filesystem type, and the device-then-mountpoint order remains valid, so `mount -t ext4 /dev/sdb1 /mnt/data` successfully mounts the ext4 filesystem. Option A is wrong because it reverses the arguments, treating /mnt/data as the device and /dev/sdb1 as the mountpoint. Option D is wrong because `-o loop` is used to mount a regular file as a loopback device, not a real block device like /dev/sdb1. Option E is wrong because it combines an unnecessary `-t auto` with `-o loop`, which is inappropriate for mounting a physical partition.

Answer

mount /mnt/data /dev/sdb1

Answer

mount -o loop /dev/sdb1 /mnt/data

Answer

mount -t auto /dev/sdb1 /mnt/data -o loop

Question 12

Which THREE of the following are valid Linux filesystem types that can be used for root partitions on a modern Linux system?

Accepted Answer

XFS. XFS (A) is a valid Linux native filesystem, long supported as a root filesystem and the default on RHEL/CentOS, so it is correct. Btrfs (D) is a modern Linux copy-on-write filesystem with full root-partition support (including subvolumes and snapshots), making it correct. ext4 (E) is the long-standing default Linux filesystem and fully supports being mounted as the root partition, so it is correct. NTFS (B) is Microsoft's Windows filesystem and FAT32 (C) is a legacy FAT variant; although Linux can mount them via drivers, neither is a valid native Linux filesystem type for a root partition on a modern system.

Answer

NTFS

Answer

FAT32

Question 13

After extending the logical volume, the df output still shows 100G. What is the most likely reason?

Accepted Answer

The filesystem on the logical volume has not been resized.. `lvextend` only increases the size of the logical volume at the block device level. The filesystem (e.g., ext4, XFS) still sees the original size until it is explicitly resized with a command like `resize2fs` (for ext4) or `xfs_growfs` (for XFS). The `df` command reports filesystem usage, not the underlying block device size, so the filesystem must be grown to match the LV.

Answer

lvresize must be used instead of lvextend.

Answer

The kernel has not detected the new size; reboot required.

Answer

The mount point must be remounted with the 'remount' option.

Question 14

A system administrator receives an alert that disk /dev/sda is predicted to fail soon. The server uses LVM, and /dev/sda is part of a volume group named vg_system. Which of the following is the best course of action to replace the failing disk without downtime?

Accepted Answer

Use pvmove to move physical extents to another disk, then remove the old disk.. Pvmove relocates physical extents from /dev/sda to another physical volume in the same volume group while the filesystem remains online and accessible. This allows the failing disk to be removed from vg_system without any downtime, preserving LVM metadata and data integrity.

Answer

Use dd to clone /dev/sda to a new disk and then replace.

Answer

Use ddrescue to copy data, then replace the disk.

Answer

Remove /dev/sda from the volume group and add a new disk.

Question 15

A system administrator needs to create a new ext4 filesystem on /dev/sdb1 with a reserved block percentage of 2% instead of the default 5%. Which command should be used?

Accepted Answer

mkfs.ext4 -m 2 /dev/sdb1. The `-m` flag in `mkfs.ext4` sets the reserved block percentage for the superuser, and specifying `-m 2` overrides the default of 5% to reserve only 2% of the blocks on the new ext4 filesystem on /dev/sdb1.

Answer

mkfs.ext4 -R 2 /dev/sdb1

Answer

mkfs.ext4 -r 2 /dev/sdb1

Answer

tune2fs -m 2 /dev/sdb1