EX200 Configure local storage Practice Test 6 — 15 Questions

Question 1

A system fails to mount an XFS filesystem at boot. The /etc/fstab entry is: UUID=abc123 /mnt xfs defaults 0 0. Running mount -a shows: 'mount: wrong fs type, bad option, bad superblock on /dev/sdb1'. Which is the most likely cause?

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

Accepted Answer

The filesystem on /dev/sdb1 is not XFS but ext4.. The error 'wrong fs type, bad option, bad superblock' occurs when the device exists but the filesystem type does not match or the superblock is unreadable. Since the error explicitly mentions /dev/sdb1, the UUID must have resolved to that device. Therefore, a UUID mismatch would produce a different error like 'can't find UUID=abc123' or 'no such device'. The most likely cause is that /dev/sdb1 is not formatted as XFS (e.g., it is ext4). A missing mount point gives 'No such file or directory', and kernel XFS support issues typically produce 'unknown filesystem type'.

Answer

The UUID specified in fstab does not match the actual UUID of /dev/sdb1.

Answer

The mount point /mnt does not exist.

Answer

The kernel does not have XFS support enabled.

Question 2

Which single command shows the UUID of a filesystem on /dev/sdb1?

Accepted Answer

blkid /dev/sdb1. The `blkid /dev/sdb1` command queries the libblkid library to read the filesystem metadata directly from the block device, displaying attributes including the UUID (Universally Unique Identifier) stored in the superblock. This is the standard, single-purpose command to retrieve the UUID of a specific partition.

Answer

df -h

Answer

mount

Answer

fdisk -l

Question 3

Which TWO commands can be used to create a physical volume for LVM? (Choose exactly two.)

Accepted Answer

pvcreate /dev/sdb1. The `pvcreate` command initializes a block device (such as a partition or an entire disk) for use as a physical volume in LVM. Option B targets a partition `/dev/sdb1`, and option C targets the whole disk `/dev/sdb` — both are valid devices that can be initialized as physical volumes, as LVM can operate on either.

Answer

mkfs.ext4

Answer

lvcreate

Answer

vgcreate

Question 4

Which THREE filesystem types are natively supported in RHEL 8/9 for local storage? (Choose exactly three.)

Accepted Answer

vfat. A is correct because vfat (FAT32) is natively supported in RHEL 8/9 for local storage, primarily for compatibility with UEFI boot partitions and removable media. The kernel includes the vfat module, and mkfs.vfat is available from the dosfstools package, allowing creation and mounting of FAT32 filesystems without additional software.

Answer

ntfs

Answer

btrfs

Question 5

Which TWO commands can be used to list block devices and their attributes? (Choose exactly two.)

Accepted Answer

lsblk. B (lsblk) is correct because it lists all block devices (e.g., /dev/sda, /dev/nvme0n1) and displays their attributes such as size, type, mount point, and model in a tree-like format by reading the sysfs filesystem. E (blkid) is correct because it shows block device attributes like UUID, filesystem type, and LABEL by querying the libblkid library, which reads metadata directly from the device.

Answer

fdisk -l

Answer

du

Answer

df

Question 6

A junior admin receives a ticket: 'The /var partition is filling up quickly. The server has an extra 100GB disk /dev/sdb. The /var filesystem is on logical volume lv_var in volume group vg_system. Currently, vg_system has no free extents. The admin's plan: create a new physical volume on /dev/sdb, extend vg_system, extend lv_var, and resize the filesystem. He runs: pvcreate /dev/sdb; vgextend vg_system /dev/sdb; lvextend -L+100G /dev/vg_system/lv_var; resize2fs /dev/vg_system/lv_var. The system reports error: 'resize2fs: Invalid argument while trying to open /dev/vg_system/lv_var'. What is the most likely mistake?

Accepted Answer

He used resize2fs instead of xfs_growfs because /var is typically XFS.. The error 'resize2fs: Invalid argument while trying to open /dev/vg_system/lv_var' indicates that the filesystem on lv_var is not ext2/3/4 but likely XFS. RHEL 8/9 defaults to XFS for /var, and XFS requires xfs_growfs (which operates on a mount point, not a block device) instead of resize2fs. Using resize2fs on an XFS filesystem produces this exact error.

Answer

He should have used lvresize instead of lvextend.

Answer

He forgot to run partprobe after pvcreate.

Answer

The lvextend command failed because vg_system has no free extents.

Question 7

A production server runs RHEL 8 with a software RAID 5 array (/dev/md0) composed of three disks: /dev/sda, /dev/sdb, /dev/sdc. The array is used to store database files. The server experiences a disk failure on /dev/sdc. The admin replaces /dev/sdc with an identical disk and wants to rebuild the array. He runs: mdadm /dev/md0 --add /dev/sdc. The command completes without error, but the array shows a degraded state after several hours. What should the admin do next?

Accepted Answer

Run mdadm --detail /dev/md0 to check the status and rebuild progress.. After adding a replacement disk to a RAID 5 array, the rebuild process begins automatically but may take hours depending on disk size and I/O load. Running `mdadm --detail /dev/md0` allows the admin to check the current state, rebuild progress (e.g., percentage complete), and any errors that might have stalled the rebuild. This is the first diagnostic step to determine if the rebuild is still ongoing, has failed, or is degraded for another reason.

Answer

Rebuild will happen automatically; just wait longer.

Answer

Recreate the array using mdadm --create with the same parameters.

Answer

Format /dev/sdc with a filesystem before adding to the array.

Question 8

A system administrator is configuring a new RHEL 9 server with two 500GB SSDs. The requirement: create a 200GB XFS filesystem for /srv/data that is resilient to disk failure. The admin decides to create a RAID 1 (mirror) using mdadm with partitions on each disk: /dev/sda1 and /dev/sdb1, each 200GB. He creates the partitions with fdisk, then runs: mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1. The array is created and synced. He then creates a physical volume, volume group, and logical volume on top of /dev/md0, formats with XFS, and mounts. Later, a disk fails. After replacing the failed disk, he recreates the partition with identical size and runs: mdadm /dev/md0 --add /dev/sdb1. The command fails with 'Device /dev/sdb1 is busy'. What is the most likely cause?

Accepted Answer

The kernel still sees the old partition table; need to run partprobe to reread the partition table.. After replacing a failed disk and recreating the partition, the kernel's in-memory partition table still reflects the old state. The `mdadm --add` command fails with 'Device busy' because the kernel sees the old partition layout and may still hold references to the old partition. Running `partprobe` (or `partx -a`) forces the kernel to reread the partition table from the disk, clearing the stale state and allowing the new partition to be added to the RAID array.

Answer

The replacement disk was not initialized with an mdadm superblock before adding.

Answer

The /dev/md0 array is still in a clean state and does not need the disk yet.

Answer

The /dev/sdb1 partition is already part of another md array.

Question 9

A RHEL 8 system has an ext4 filesystem on /dev/sdb1 mounted at /backup. The admin runs out of space and wants to extend the filesystem. He adds a new disk /dev/sdc, creates a partition /dev/sdc1 (all space), adds it to LVM by creating a PV and extending the VG that contains the LV for /backup. He then extends the logical volume with lvextend -L+20G /dev/vg_backup/lv_backup. The command succeeds, but the filesystem still shows the old size. What did he forget to do?

Accepted Answer

Resize the filesystem using resize2fs.. When extending an LVM logical volume, the `lvextend` command only expands the logical volume's block device, not the filesystem residing on it. After extending the LV, the admin must run `resize2fs` (for ext4) to resize the filesystem to match the new LV size. Without this step, the kernel still sees the old filesystem metadata, so `df -h` reports the original size.

Answer

Reboot the system to recognize the new space.

Answer

Run lvchange -ay to activate the logical volume.

Answer

Unmount the filesystem before extending the LV.

Question 10

During a system audit, an administrator finds that a filesystem mounted at /srv/data with ext4 is not showing in /etc/fstab. Further investigation reveals that the underlying device is an LVM logical volume lv_data in vg_data. The administrator wants to ensure the filesystem is mounted at boot. He adds an entry to /etc/fstab using the device path /dev/vg_data/lv_data. On reboot, the system fails to mount the filesystem and enters emergency mode. The logical volume and filesystem are intact. What is the most likely reason for the failure?

Accepted Answer

The device path /dev/vg_data/lv_data is a symlink that may not be available; use /dev/mapper/vg_data-lv_data or UUID.. The device path /dev/vg_data/lv_data is a symbolic link created by LVM that may not be available early in the boot process because the device mapper nodes are not yet created. The correct approach is to use the stable /dev/mapper/vg_data-lv_data path or the filesystem UUID in /etc/fstab to ensure reliable mounting at boot.

Answer

The mount point /srv/data does not exist.

Answer

The filesystem type specified in fstab is incorrect.

Answer

The logical volume is not activated at boot because lvm2-lvmetad is not running.

Question 11

A system administrator runs the following command: # vgextend mydata-vg /dev/sdc. After successfully extending the volume group, what is the next step to make the additional space available in the logical volume mydata-lv?

Accepted Answer

lvextend -l +100%FREE /dev/mydata-vg/mydata-lv. After extending the volume group with vgextend, you must extend the logical volume to use the new free space. The command lvextend -l +100%FREE /dev/mydata-vg/mydata-lv allocates all remaining free extents in the volume group to the logical volume, making the additional space available for the filesystem.

Answer

xfs_growfs /data

Answer

resize2fs /dev/mydata-vg/mydata-lv

Answer

lvextend -L +10G /dev/mydata-vg/mydata-lv

Question 12

A system administrator is managing a Red Hat Enterprise Linux 9 server that uses LVM for storage. The volume group 'vgdata' contains two 500 GB physical volumes (sdb and sdc) with a logical volume 'lvdata' of 800 GB formatted with XFS and mounted at /data. The administrator adds a new 200 GB disk /dev/sdd and intends to use all of its capacity to extend lvdata. The following commands are executed in order: pvcreate /dev/sdd, vgextend vgdata /dev/sdd, lvextend -l +100%FREE /dev/vgdata/lvdata. The lvextend command completes successfully, but running 'df -h /data' still shows 800 GB. What is the most likely reason?

Accepted Answer

The filesystem has not been grown after extending the logical volume.. After extending the logical volume with `lvextend`, the underlying block device has more space, but the filesystem still sees the original size. For XFS, you must run `xfs_growfs /data` (or `xfs_growfs /dev/vgdata/lvdata`) to expand the filesystem to use the newly allocated extents. Without this step, `df -h` continues to report the old filesystem size.

Answer

The volume group 'vgdata' is not active, so the new space is ignored.

Answer

The logical volume was extended using a snapshot instead of the original.

Answer

The physical volume was not created correctly and the space is not available.

Question 13

Refer to the exhibit. An administrator runs 'mount -o remount,ro /data' and then 'mount' shows /data as read-only. Later, the system is rebooted. What is the state of /data after reboot?

Accepted Answer

/data will be mounted read-write because fstab specifies defaults (rw).. The `mount -o remount,ro /data` command changes the mount state only for the current session; it does not modify the `/etc/fstab` entry. The `defaults` mount option in fstab implies `rw` (read-write). After a reboot, the system reads fstab and mounts `/data` according to its persistent configuration, which is read-write.

Answer

/data will be mounted read-only because the remount persists across reboots.

Answer

/data will not be mounted because the filesystem is marked as read-only.

Answer

/data will be mounted read-only because the kernel remembers the last mount state.

Question 14

Refer to the exhibit. After extending the logical volume, why does the df output still show 5.0G?

Accepted Answer

The filesystem needs to be resized with xfs_growfs.. The output shows the logical volume was extended (e.g., from 5G to 10G), but the filesystem itself has not been resized to use the new space. For XFS filesystems, the `xfs_growfs` command must be run to expand the filesystem to match the logical volume size. The `df` command reports filesystem usage, not block device size, so it still shows 5.0G until the filesystem is grown.

Answer

The lvextend command failed silently.

Answer

The filesystem type is ext4 and requires resize2fs.

Answer

The mount point /data is not accessible.

Question 15

Refer to the exhibit. An administrator attempts to mount the partition but receives an error. Which command should be run first to resolve the issue?

Accepted Answer

file -s /dev/sdc1. The error indicates that the partition /dev/sdc1 does not contain a recognized filesystem. Running 'file -s /dev/sdc1' displays the actual data on the partition, confirming whether a filesystem exists or if the partition is raw. This diagnostic step is essential before any repair or formatting action.

Answer

xfs_repair /dev/sdc1

Answer

partprobe /dev/sdc

Answer

mkfs.xfs /dev/sdc1