LFCS Storage Management Practice Test 5 — 15 Questions

Question 1

Which TWO of the following are valid ways to mount a filesystem with the 'noexec' option to prevent execution of binaries?

Accepted Answer

mount -o noexec /dev/sdb1 /mnt/data. The `mount -o noexec /dev/sdb1 /mnt/data` command explicitly sets the `noexec` mount option at runtime, which prevents execution of any binaries on the mounted filesystem. This is a direct and valid way to apply the `noexec` flag without modifying configuration files.

Answer

Add 'exec' to the fourth field of /etc/fstab for the entry.

Answer

Add 'defaults' to the fourth field of /etc/fstab for the entry.

Answer

mount --bind /mnt/data1 /mnt/data2

Question 2

Which THREE of the following are potential causes for a system failing to boot with 'Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block'?

Accepted Answer

The initramfs image is missing the necessary tools to mount the root filesystem, e.g., missing filesystem driver.. The kernel relies on the initramfs to load necessary filesystem drivers (e.g., ext4, XFS, Btrfs) and tools (e.g., fsck, lvm) to mount the root filesystem. If the initramfs is missing the required driver for the root filesystem type, the kernel will fail with 'VFS: Unable to mount root fs' because it cannot access the block device containing the root partition.

Answer

The SATA cable for the root disk is loose, causing the disk to be detected intermittently.

Answer

The partition table on the root disk uses GPT but the BIOS is set to legacy boot.

Question 3

Which TWO of the following commands can be used to check and repair an ext4 filesystem?

Accepted Answer

fsck.ext4 /dev/sdb1. A is correct because `fsck.ext4` is the dedicated front-end for checking and repairing ext4 filesystems, invoking the `e2fsck` program with ext4-specific defaults. It performs a full consistency check of the filesystem metadata, including the journal, inode tables, and block bitmaps, and can automatically repair detected issues when run with the `-y` or `-p` options.

Answer

xfs_repair /dev/sdb1

Answer

mkfs.ext4 /dev/sdb1

Answer

btrfs check /dev/sdb1

Question 4

You are managing a Linux server that hosts a critical application using a 500GB ext4 filesystem on an LVM logical volume. The application writes large log files that are rotated weekly. Recently, the system has been experiencing intermittent performance degradation and occasional 'Input/output error' messages when writing to the log directory. The disk (SSD) is relatively new, and SMART tests report no errors. The filesystem is not full, with 60% usage. You notice that the errors occur more frequently during peak write times. Which of the following is the most appropriate first step to diagnose and resolve the issue?

Accepted Answer

Unmount the filesystem and run 'e2fsck -f' to check and repair filesystem corruption.. The correct first step. The symptoms of intermittent I/O errors on a filesystem that is not full and with a healthy SSD suggest filesystem corruption rather than hardware failure. Running 'e2fsck -f' will force a check and repair of the ext4 filesystem, which can resolve the errors. Option A is incorrect because adding an LVM cache layer would only improve performance but not fix corruption. Option C is incorrect because replacing the SSD is not warranted given clean SMART tests. Option D is incorrect because mounting with 'noatime' reduces write overhead but does not address filesystem corruption.

Answer

Add an LVM cache layer to improve write performance.

Answer

Replace the SSD immediately as it is likely failing despite SMART tests.

Answer

Mount the filesystem with the 'noatime' option to reduce write overhead.

Question 5

A company's database server uses LVM for storage. The system administrator notices that the logical volume /dev/vg_db/lv_data is at 95% capacity. The server is in production and cannot be taken offline. The volume group vg_db has free physical extents. Which command sequence should the administrator use to safely increase the size of the logical volume and filesystem without unmounting?

Accepted Answer

lvextend -L +10G /dev/vg_db/lv_data; resize2fs /dev/vg_db/lv_data. It first extends the logical volume using `lvextend -L +10G` to allocate additional physical extents from the volume group, then resizes the ext4 filesystem online with `resize2fs` to utilize the new space. Both operations can be performed without unmounting the filesystem, as ext4 supports online resizing and LVM allows live extension of logical volumes.

Answer

lvextend /dev/vg_db/lv_data /dev/sdb; resize2fs /dev/vg_db/lv_data

Answer

lvresize -L +10G /dev/vg_db/lv_data; mkfs.ext4 /dev/vg_db/lv_data

Answer

lvextend -L +10G /dev/vg_db/lv_data; mount -o remount /dev/vg_db/lv_data

Question 6

After adding a new SCSI disk to a server running Linux, the system fails to boot with the error: 'Kernel panic - not syncing: VFS: Unable to mount root fs'. The root filesystem is on LVM. What is the most likely cause?

Accepted Answer

The initramfs was not regenerated after the disk addition, missing LVM tools.. When the root filesystem resides on LVM, the initramfs must contain the LVM tools and modules (e.g., lvm2, device-mapper) to activate the logical volumes before the kernel can mount the root filesystem. Adding a new SCSI disk does not inherently require regenerating the initramfs, but if the initramfs was not rebuilt after the LVM configuration changed (e.g., after adding a disk that becomes part of a volume group), it may lack the necessary LVM support, causing a kernel panic when it cannot mount the root LV.

Answer

The /etc/fstab entry for the new disk is missing.

Answer

The GRUB configuration is incorrect.

Answer

The new disk's partition table is corrupt.

Question 7

A system administrator needs to set up software RAID1 on a server for /data. The available disks are /dev/sdb (500GB) and /dev/sdc (1TB). What is the maximum usable capacity of the RAID1 array?

Accepted Answer

500GB. RAID1 (mirroring) writes identical data to all disks in the array, so the usable capacity is limited by the smallest disk. With /dev/sdb at 500GB and /dev/sdc at 1TB, the maximum usable capacity is 500GB. The remaining space on /dev/sdc (500GB) is unusable in the RAID1 array because it cannot be mirrored.

Answer

250GB

Answer

1TB

Answer

1.5TB

Question 8

An administrator has enabled quotas on the /home filesystem by adding usrquota,grpquota to /etc/fstab and remounting. Then ran quotacheck -cug /home and it completed successfully. However, users are still able to write beyond their assigned soft limits. What step is missing?

Accepted Answer

Running quotaon to activate quotas.. The missing step is activating quotas with `quotaon`. Even after configuring `/etc/fstab` with `usrquota,grpquota`, remounting the filesystem, and running `quotacheck -cug` to create the quota database files (`aquota.user` and `aquota.group`), quotas remain inactive until explicitly enabled with `quotaon`. Without this command, the kernel does not enforce quota limits, allowing users to exceed soft limits without warning.

Answer

Setting limits with edquota.

Answer

Running repquota to view quotas.

Answer

Setting limits with setquota.

Question 9

Which TWO commands can display disk space usage of mounted filesystems? (Choose two.)

Accepted Answer

du. The `du` command (disk usage) can display disk space usage of mounted filesystems by summarizing the space used by files and directories, typically with the `-h` option for human-readable output. While `du` is primarily used for per-directory usage, it can be used to check usage on mounted filesystems when run from their mount points. The `df` command (disk free) is the standard tool for displaying disk space usage of mounted filesystems, showing total, used, and available space for each mounted partition.

Answer

parted

Answer

fdisk

Answer

lsblk

Question 10

Which THREE steps are required to create a new ext4 filesystem on /dev/sdc1 and ensure it is automatically mounted at /mnt/data at boot? (Choose three.)

Accepted Answer

mkfs.ext4 /dev/sdc1. B is correct because `mkfs.ext4 /dev/sdc1` creates a new ext4 filesystem on the specified partition. This is the fundamental step to format the device with the ext4 filesystem type, which is required before the partition can be mounted and used for data storage.

Answer

e2label /dev/sdc1 data

Answer

mount /dev/sdc1 /mnt/data

Question 11

A large e-commerce platform runs on a database server that uses LVM thin provisioning. The thin pool is overcommitted at 200% (pool size 1TB, thin volumes total 2TB). Suddenly, the database reports write errors and performance degrades drastically. The administrator checks the system and finds that the thin pool is completely full. What is the immediate effect on the thin volumes, and what should the administrator do to restore normal operation without data loss?

Accepted Answer

The volumes become read-only; administrator must add more physical storage to the volume group and extend the thin pool.. When an LVM thin pool is completely full, writes to thin volumes fail and the volumes become read-only to prevent data corruption. This matches option C. The correct action is to add more physical storage to the volume group and extend the thin pool, which will allow normal writes to resume. Option A is incorrect because volumes do not continue to operate; they become read-only. Option B is incorrect because corruption does not occur immediately. Option D is false because thin pools do not auto-extend.

Answer

The volumes continue to operate but with severe slowdown; administrator must delete unnecessary snapshots.

Answer

The volumes become corrupted; administrator must restore from backup.

Answer

The volumes automatically extend the pool using metadata space; no action needed.

Question 12

A system administrator is setting up a new backup server. The server has two 4TB disks /dev/sda and /dev/sdb. The administrator decides to create a RAID1 array and then an LVM volume group on top of the RAID device. After creating the RAID1 array /dev/md0, they create a physical volume, volume group named vg_backup, and a logical volume lv_data of size 2TB. Then they format with ext4 and mount at /backup. During testing, they realize that the backup data volume will likely exceed 2TB eventually. They want to expand the filesystem to use all available space in the RAID array. What is the correct procedure?

Accepted Answer

lvextend -l +100%FREE /dev/vg_backup/lv_data, resize2fs /dev/vg_backup/lv_data.. Lvextend -l +100%FREE extends the logical volume to use all free space in the volume group, and resize2fs can grow the ext4 filesystem online without requiring unmounting. Option B is incorrect because unmounting is unnecessary for online resize. Option C does not use all available space in one filesystem. Option D is unnecessary as the RAID array already has sufficient space; the goal is to expand the filesystem within the existing volume group.

Answer

Unmount /backup, lvextend -l +100%FREE /dev/vg_backup/lv_data, resize2fs /dev/vg_backup/lv_data, mount /backup.

Answer

Create a new logical volume and mount it separately.

Answer

Add new disk to RAID array, then extend LVM.

Question 13

A sysadmin is troubleshooting an issue where a software RAID1 array fails to assemble after a reboot. The array was created with mdadm using /dev/sdb1 and /dev/sdc1. The administrator checks /proc/mdstat but the array is not present. They attempt to assemble manually with mdadm --assemble /dev/md0 /dev/sdb1 /dev/sdc1, but it requires a repair. After repair, the array works. To prevent this from happening again, what should the administrator do?

Accepted Answer

Add an entry for the array in /etc/mdadm/mdadm.conf.. Adding an entry for the array in /etc/mdadm/mdadm.conf (or /etc/mdadm.conf) ensures that mdadm reads the configuration at boot and automatically assembles the RAID array. Without this entry, the system does not know which devices belong to the array, causing it to fail to assemble after reboot. Option A (using UUIDs) is a good practice but not mandatory; the array can still be assembled by device names if configured. Option B (setting partition type to 'Linux RAID') is helpful for disk identification but does not directly address the assembly configuration. Option C (rebuilding initramfs) may be required after adding the config, but the primary solution is to add the config entry.

Answer

Use UUIDs instead of device names in configuration.

Answer

Set the partition type to 'Linux RAID' on both partitions.

Answer

Rebuild the initramfs.

Question 14

A server’s root filesystem on LVM is nearly full. The administrator has added a new 20GB disk and created a physical volume on it. They added the PV to the volume group containing root, then extended the root logical volume by 10GB. Next, they ran resize2fs on the mounted root filesystem. After the resize, the server continues to function. However, upon reboot, the system fails to boot and enters emergency mode. What is the most likely cause?

Accepted Answer

The initramfs needs to be regenerated to include the new disk.. After adding a new physical volume to an LVM volume group containing the root filesystem, the initramfs must be regenerated to include the necessary LVM tools and device information so that the root volume can be activated early in the boot process. Without rebuilding the initramfs, the system may fail to mount the root filesystem after reboot. Option A is irrelevant because the kernel is unchanged. Option B is incorrect because the /etc/fstab entry, typically using UUID or logical volume path, remains valid. Option C is unlikely because resize2fs succeeded and the filesystem is consistent after running it immediately.

Answer

The GRUB configuration is missing the new kernel.

Answer

The /etc/fstab entry for root is incorrect.

Answer

The filesystem was not resized correctly.

Question 15

A system administrator needs to increase the size of an existing filesystem mounted at /var/www. The filesystem resides on a logical volume /dev/vg_web/lv_web. The volume group has free space. The administrator runs: lvextend -L +5G /dev/vg_web/lv_web, and then resize2fs /dev/vg_web/lv_web. The commands complete without error, but df shows the filesystem size did not change. What is the most likely reason?

Accepted Answer

The filesystem is not ext4; it is XFS, which requires xfs_growfs.. The `resize2fs` command is specific to ext2, ext3, and ext4 filesystems. Since the filesystem is mounted at /var/www and the `lvextend` succeeded, the most likely reason `df` shows no change is that the filesystem is XFS, which requires the `xfs_growfs` command to resize online. XFS does not use `resize2fs`, and running it on an XFS filesystem would either fail silently or have no effect.

Answer

The resize2fs command was run without the device path; it requires the mount point.

Answer

The volume group does not have enough free extents; the lvextend failed silently.

Answer

The logical volume was not properly extended; need to use pvresize.