EX200 Configure local storage Practice Test 3 — 15 Questions

Question 1

An administrator wants to add the two 2G disks (sdc and sdd) as physical volumes, extend the 'data' logical volume in volume group 'vg' by 2G, and grow the filesystem. Which sequence of commands should be used?

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

Accepted Answer

pvcreate /dev/sdc /dev/sdd; vgextend vg /dev/sdc /dev/sdd; lvextend -L +2G /dev/vg/lv_data; xfs_growfs /data. It follows the correct sequence: create physical volumes on both disks, extend the volume group with both disks in a single command, extend the logical volume by exactly 2G using the `+` sign, and then grow the XFS filesystem using `xfs_growfs` with the mount point `/data`. The `+` in `lvextend -L +2G` is critical to add 2G rather than resize to 2G total, and `xfs_growfs` requires the mount point (or a block device) for XFS filesystems.

Answer

pvcreate /dev/sdc /dev/sdd; vgextend vg /dev/sdc /dev/sdd; lvresize -L 2G /dev/vg/lv_data; xfs_growfs /data

Answer

pvcreate /dev/sdc /dev/sdd; vgextend vg /dev/sdc /dev/sdd; lvextend -L +2G /dev/vg/lv_data; resize2fs /dev/vg/lv_data

Answer

pvcreate /dev/sdc /dev/sdd; vgextend vg /dev/sdc; vgextend vg /dev/sdd; lvextend -L +2G /dev/vg/lv_data; xfs_growfs /dev/vg/lv_data

Question 2

A system administrator is setting up storage for a new application server. The application requires two separate filesystems: one for the database (needs to be at least 10GiB) and one for logs (needs at least 5GiB). The server has a single 20GiB disk /dev/sda. The administrator plans to use LVM and a single volume group 'vg_app'. They create physical volume on /dev/sda, create the volume group, and then create two logical volumes: 'lv_db' of 10GiB and 'lv_logs' of 5GiB. They format lv_db as ext4 and lv_logs as xfs, and mount them at /db and /logs respectively. After rebooting, the system fails to mount /logs. What is the most likely cause?

Accepted Answer

The /logs entry is missing from /etc/fstab.. The most likely cause is that the /logs entry is missing from /etc/fstab. After reboot, the system relies on /etc/fstab to mount filesystems automatically. Since the administrator created and mounted the filesystem manually, but did not add an entry for /logs in /etc/fstab, the mount fails on reboot. The database mount may succeed if it was added, but the logs mount fails due to the missing fstab entry.

Answer

The logical volume 'lv_logs' overlaps with 'lv_db'.

Answer

The physical volume /dev/sda is not recognized by LVM after reboot.

Answer

The volume group 'vg_app' is not automatically activated.

Question 3

Order the steps to create a new LVM logical volume of 5 GiB named 'lv_data' in volume group 'vg_data'.

Accepted Answer

1. pvcreate, 2. vgcreate, 3. lvcreate, 4. mkfs, 5. mount. The correct sequence for creating an LVM logical volume is: first create physical volumes (PVs) with pvcreate, then the volume group (VG) with vgcreate, then the logical volume (LV) with lvcreate, then a filesystem on the LV with mkfs, and finally mount it. Any deviation from this order will fail because each step depends on the previous ones.

Answer

1. vgcreate, 2. pvcreate, 3. lvcreate, 4. mkfs, 5. mount

Answer

1. pvcreate, 2. lvcreate, 3. vgcreate, 4. mkfs, 5. mount

Answer

1. pvcreate, 2. vgcreate, 3. mkfs, 4. lvcreate, 5. mount

Question 4

Put the steps to configure a new swap partition of 2 GiB on /dev/sdc1 and enable it in order.

Accepted Answer

First, run mkswap /dev/sdc1 to format the partition as swap. Then, run swapon /dev/sdc1 to activate it. Finally, add an entry to /etc/fstab to make it persistent across reboots.. Swap configuration involves partitioning, formatting, enabling, and making persistent in fstab.

Answer

First, run swapon /dev/sdc1 to activate the swap. Then, run mkswap /dev/sdc1 to format it. Finally, add an entry to /etc/fstab.

Answer

First, add an entry to /etc/fstab for /dev/sdc1. Then, run mkswap /dev/sdc1. Finally, run swapon /dev/sdc1.

Answer

First, run mkswap /dev/sdc1. Then, add an entry to /etc/fstab. Finally, run swapon /dev/sdc1.

Question 5

Match each systemd unit type to its purpose.

Accepted Answer

service: Manages daemon processes. Systemd unit types define system resources: service (daemons), socket (IPC), target (group/synchronization), timer (scheduled activation). Common confusions involve mixing mount with service and target with timer.

Answer

service: Manages file system mount points

Answer

timer: Groups units to define synchronization points

Question 6

Match each cron syntax field to its meaning.

Accepted Answer

minute: 0-59. The five fields in a cron syntax are (in order): minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-7). Common confusions include swapping the minute and hour ranges.

Answer

minute: 0-23

Question 7

Which command initializes a disk partition as a physical volume for LVM?

Accepted Answer

pvcreate. `pvcreate` is the LVM command specifically designed to initialize a disk partition as a physical volume (PV), which is the first step in creating an LVM logical volume. Without a PV, LVM cannot manage the underlying block device. The command writes LVM metadata to the partition, marking it as available for inclusion in a volume group.

Answer

fdisk

Answer

vgcreate

Answer

lvcreate

Question 8

Which command shows the amount of disk space used and available on each mounted filesystem?

Accepted Answer

df -h. The `df -h` command displays disk space usage for all mounted filesystems, showing total, used, and available space in human-readable format (e.g., GB, MB). This directly answers the question about disk space on each mounted filesystem.

Answer

fdisk -l

Answer

du -sh

Answer

lsblk

Question 9

Which file contains the list of filesystems to be mounted at system startup?

Accepted Answer

/etc/fstab. The /etc/fstab file is the system configuration file that defines static filesystem information, including devices, mount points, filesystem types, mount options, dump frequency, and fsck pass order. During system startup, the mount -a command (typically run by systemd or init scripts) reads /etc/fstab to mount all filesystems listed there, making it the definitive source for automatic mounting at boot.

Answer

/etc/rc.local

Answer

/etc/filesystems

Answer

/etc/mtab

Question 10

After adding a new disk to a volume group, which command is used to extend a logical volume by 2GB?

Accepted Answer

lvextend -L +2G /dev/vg/lv. After adding a new disk to a volume group, the `lvextend -L +2G /dev/vg/lv` command extends the logical volume by exactly 2 GB. The `-L +2G` syntax specifies the additional size to add, and the target is the logical volume path. This is the standard LVM command for increasing logical volume size without specifying a physical extent range.

Answer

vgextend vg /dev/sdb

Answer

resize2fs /dev/vg/lv

Answer

pvcreate /dev/sdb

Question 11

A filesystem reports 0% free space in df -h, but when checking the directory size with du -sh, it shows much less usage. What is the most likely cause?

Accepted Answer

Deleted files still held open by processes. When a file is deleted while a process still holds an open file descriptor to it, the file's data blocks remain allocated on disk and are not freed until the process closes the descriptor. The `df` command reports disk usage based on the filesystem's block allocation, which still counts those blocks as used, while `du` calculates usage by walking the directory tree and cannot see the deleted file's data, leading to the discrepancy.

Answer

Filesystem is corrupted

Answer

The disk has bad sectors

Answer

Filesystem is mounted with noexe

Question 12

Which of the following is true regarding shrinking logical volumes?

Accepted Answer

XFS filesystems cannot be shrunk. B is correct because XFS filesystems do not support shrinking. The XFS design is based on allocation groups and a log-structured metadata layout that makes online or offline shrinking infeasible without significant filesystem restructuring. This is a fundamental limitation of XFS, unlike ext4 which can be shrunk offline.

Answer

You can reduce a volume while it is mounted if you use resize2fs

Answer

Reducing an LVM volume is a simple process

Answer

Ext4 filesystems support online shrinking

Question 13

A system administrator tries to mount a filesystem but receives the error: 'mount: /dev/sdb1 is already mounted or /data busy'. The filesystem is not listed in the mount output. What is the most likely cause?

Accepted Answer

The mount point /data is in use by a process. The error message 'mount: /dev/sdb1 is already mounted or /data busy' indicates that the mount point /data is currently in use by a process, preventing the mount operation. Even though the filesystem is not listed in the mount output, a process may have an open file descriptor or be using /data as its current working directory, which keeps the directory busy. The 'lsof' or 'fuser' commands can be used to identify the offending process.

Answer

The kernel does not have the filesystem driver loaded

Answer

The device is already mounted on another mount point

Answer

The filesystem is corrupted

Question 14

Which of the following is the correct way to persistently mount a filesystem using its UUID?

Accepted Answer

UUID=1234 /mnt xfs defaults 0 0. The /etc/fstab entry uses the 'UUID=' prefix followed by the actual UUID value to persistently mount a filesystem. The kernel reads this line at boot time and resolves the UUID to the corresponding block device, ensuring the mount is consistent regardless of device name changes.

Answer

LABEL=1234 /mnt xfs defaults 0 0

Answer

/dev/disk/by-uuid/1234 /mnt xfs defaults 0 0

Answer

PARTUUID=1234 /mnt xfs defaults 0 0

Question 15

Which command can be used to create a logical volume using all available free space in a volume group?

Accepted Answer

lvcreate -l 100%FREE -n lvdata vgdata. The `-l 100%FREE` flag allocates all unallocated physical extents in the volume group, which is the precise way to use all available free space. Option D (`-l 100%VG`) is incorrect because it attempts to allocate 100% of the volume group's extents, including those already used by other logical volumes, causing the command to fail if any extents are already allocated. Therefore, only option B is correct.

Answer

lvcreate --size 20G vgdata lvdata

Answer

lvcreate -L 20G -n lvdata vgdata

Answer

lvcreate -l 100%VG -n lvdata vgdata

Answer

lvcreate -L 100%FREE -n lvdata vgdata