EX200 Create and configure file systems — 20 Questions

Question 1

A system administrator needs to create a new ext4 filesystem on /dev/sdb1 and mount it persistently at /data. Which set of commands should be used?

Accepted Answer

mkfs -t ext4 /dev/sdb1 && mkdir /data && mount /dev/sdb1 /data && echo '/dev/sdb1 /data ext4 defaults 0 0' >> /etc/fstab. It creates the ext4 filesystem with `mkfs -t ext4 /dev/sdb1`, creates the mount point directory with `mkdir /data`, mounts the filesystem immediately with `mount /dev/sdb1 /data`, and then adds an entry to `/etc/fstab` using the correct format (device, mount point, filesystem type, options, dump, pass) to ensure the mount persists across reboots. The `&&` operator ensures each command only runs if the previous one succeeds, which is a safe practice for scripting this task.

Answer

mkfs.ext4 /dev/sdb1 && mount /dev/sdb1 /data

Answer

mkfs -t ext4 /dev/sdb1 && echo '/dev/sdb1 /data ext4 defaults 0 0' >> /etc/fstab && mount /data

Answer

mkfs.ext4 /dev/sdb1 && mkdir /data && mount /dev/sdb1 /data && blkid /dev/sdb1 >> /etc/fstab

Question 2

A file server is experiencing slow write performance. The admin suspects the filesystem is nearly full. Which command should be used to check disk usage per partition?

Accepted Answer

df -h. The `df -h` command displays disk space usage for all mounted filesystems in human-readable format (e.g., GB, MB). This directly answers the admin's need to check per-partition usage and identify if a filesystem is nearly full, which can cause slow write performance due to lack of free space.

Answer

df -i

Answer

du -h --max-depth=1 /

Answer

du -sh /

Question 3

A technician attempts to mount an XFS filesystem from /dev/sdc1 to /mnt/backup but receives: 'mount: /mnt/backup: mount point does not exist.' The directory /mnt/backup does exist. What is the most likely cause?

Accepted Answer

SELinux context of /mnt/backup prevents mounting.. The error message 'mount: /mnt/backup: mount point does not exist' is misleading because the directory does exist. The most likely cause is that SELinux is blocking the mount due to a missing or incorrect context on the mount point. SELinux requires the mount point directory to have a specific context (e.g., `default_t` or a context matching the filesystem type) for the mount to succeed; if the context is wrong or missing, the kernel may treat the directory as nonexistent for the mount operation, resulting in the observed error. Red Hat exams often test this nuance, where SELinux can cause a 'does not exist' error even when the directory is present, leading candidates to overlook SELinux as the root cause.

Answer

The directory /mnt/backup is not empty.

Answer

The device /dev/sdc1 does not exist.

Answer

The filesystem on /dev/sdc1 is not XFS.

Question 4

A system has two 500GB disks in a RAID1 (mirror) using mdadm. One disk fails. After replacement, what is the correct procedure to restore redundancy?

Accepted Answer

Use sfdisk to copy partition table from /dev/sda to /dev/sdb, then 'mdadm --manage /dev/md0 --add /dev/sdb1'. When replacing a failed disk in a RAID1 array managed by mdadm, the new disk must have a partition table that matches the surviving disk. Using sfdisk to copy the partition table from /dev/sda to /dev/sdb ensures that the partition layout (e.g., partition type 0xFD for Linux RAID autodetect) is identical, which is required before adding the partition (e.g., /dev/sdb1) to the array with mdadm --manage --add. Simply adding the raw disk without a proper partition table would fail because mdadm expects a partition with the correct RAID superblock and partition type.

Answer

Run 'mdadm --manage /dev/md0 --add /dev/sdb'

Answer

Remove the failed disk with 'mdadm /dev/md0 --fail /dev/sdb1' then add new.

Answer

Run 'mdadm --assemble --scan' to rebuild the array automatically.

Question 5

An admin needs to mount an NFS export from server nfs.example.com:/exports/app to /mnt/app with options for read-only and no root squash. Which command is correct?

Accepted Answer

mount -t nfs -o ro,no_root_squash nfs.example.com:/exports/app /mnt/app. The `mount -t nfs -o ro,no_root_squash` command mounts the NFS export from `nfs.example.com:/exports/app` to `/mnt/app` as read-only (`ro`) and disables root squash (`no_root_squash`), which allows the root user on the client to retain root privileges when accessing files on the NFS server. The `-t nfs` specifies the NFS filesystem type, and the mount point `/mnt/app` must exist prior to execution.

Answer

mount -t nfs -o ro,root_squash nfs.example.com:/exports/app /mnt/app

Answer

mount -t nfs -o ro,no_root_squash,nosuid nfs.example.com:/exports/app /mnt/app

Answer

mount -t nfs -o rw,no_root_squash nfs.example.com:/exports/app /mnt/app

Question 6

Which command creates an XFS filesystem on /dev/nvme0n1p1 and sets the label to 'data'?

Accepted Answer

mkfs.xfs -L data /dev/nvme0n1p1. The `-L` flag in `mkfs.xfs` is used to set the filesystem label. The command `mkfs.xfs -L data /dev/nvme0n1p1` creates an XFS filesystem on the specified partition and assigns it the label 'data'.

Answer

mkfs.xfs -l data /dev/nvme0n1p1

Answer

mkfs.xfs -f /dev/nvme0n1p1

Answer

mkfs.xfs -n data /dev/nvme0n1p1

Question 7

Which TWO commands can be used to check the UUID of a filesystem on /dev/sda1?

Accepted Answer

lsblk -o UUID /dev/sda1. The `blkid` command directly queries the UUID of a block device from the libblkid cache or by reading the filesystem superblock, and `lsblk -o UUID` filters the lsblk output to show only the UUID column for the specified device. Both commands reliably retrieve the UUID of /dev/sda1.

Answer

e2label /dev/sda1

Answer

findmnt /dev/sda1

Answer

file -s /dev/sda1

Question 8

Which THREE of the following are valid options for mounting an ext4 filesystem with specific mount options in /etc/fstab?

Accepted Answer

noexec. For an ext4 filesystem, all of the following are valid mount options that can appear in /etc/fstab: noexec, relatime, noatime, suid, and nodev. The options suid and nosuid are a pair, as are dev and nodev, exec and noexec. Thus the statement that only three are valid is false.

Answer

suid

Answer

nodev

Question 9

Which TWO commands can be used to create a new directory that will serve as a mount point?

Accepted Answer

install -d /mnt/newmount. `install -d /mnt/newmount` creates the directory `/mnt/newmount` if it does not already exist, setting it up as a mount point. Option D is correct because `mkdir /mnt/newmount` is the standard command to create a directory, which can then be used as a mount point for a filesystem.

Answer

touch /mnt/newmount

Answer

ln -s /mnt /mnt/newmount

Answer

ln /mnt /mnt/newmount

Question 10

After extending the logical volume to 500G, why does df still show 250G?

Accepted Answer

The filesystem was not resized after extending the LV.. Extending a logical volume (LV) with `lvextend` only increases the block device size; the filesystem on top must be resized separately using `resize2fs` (for ext4) or `xfs_growfs` (for XFS). Without this step, the filesystem still sees the original size, so `df` reports 250G instead of 500G.

Answer

The mount point is incorrect.

Answer

The physical volume is full.

Answer

The logical volume extension failed.

Question 11

What is the most likely cause of the mount error?

Accepted Answer

The NFS server IP address is unreachable or the nfs-utils package is not installed.. The mount error is most likely caused by the NFS server being unreachable or the nfs-utils package not being installed. Without the nfs-utils package, the system lacks the necessary NFS client tools (e.g., mount.nfs, rpcbind) to mount NFS shares. If the server IP is unreachable, the mount command will fail with a timeout or 'No route to host' error, which is a common issue when network connectivity or NFS services are not properly configured.

Answer

The entry in /etc/fstab is malformed.

Answer

The filesystem type 'nfs4' is incorrect; should be 'nfs'.

Answer

The mount point /mnt/data does not exist.

Question 12

You are managing a Red Hat Enterprise Linux 9 server that hosts a critical database application. The database stores its data on an XFS filesystem mounted on /data, backed by a logical volume in a volume group named vg_db. Recently, the database team reported that write operations are failing with 'Disk quota exceeded' errors, but the filesystem still shows 40% free space. You check the filesystem quota configuration and find that no user or group quotas are set on /data. The database runs as user 'dbadmin' with group 'dba'. Which of the following is the most likely cause of the 'Disk quota exceeded' error?

Accepted Answer

An XFS project quota is configured on the /data directory, limiting the space used by the database files.. XFS project quotas can limit the total space used by a directory tree, regardless of the user or group that owns the files. Even though no user or group quotas are set, a project quota on /data restricts the database files, causing 'Disk quota exceeded' errors despite 40% free space on the filesystem.

Answer

The logical volume is thin provisioned and the data pool is full.

Answer

SELinux is blocking the database writes due to a denial.

Answer

The filesystem has run out of inodes.

Question 13

A system administrator needs to create a new ext4 filesystem on /dev/sdb1 and mount it persistently at /data. Which set of commands should be used?

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

Accepted Answer

mkfs.xfs /dev/sdb1 && mkdir /data && mount /dev/sdb1 /data && echo '/dev/sdb1 /data xfs defaults 0 0' >> /etc/fstab. Both XFS and ext4 support extended attributes by default in RHEL. However, XFS is optimized for large files and high performance, making it the recommended choice for this scenario. Option B correctly creates an XFS file system on /dev/sdb1, creates the mount point, mounts it immediately, and adds an fstab entry for persistence. Option C uses ext4, which is not as suitable for large files as XFS. Options A and D are incorrect due to wrong device or file system type.

Answer

mkfs.xfs /dev/sda1 && mkdir /data && echo '/dev/sda1 /data xfs defaults 0 0' >> /etc/fstab

Answer

mkfs.ext4 /dev/sdb1 && mkdir /data && mount /dev/sdb1 /data && echo '/dev/sdb1 /data ext4 defaults 0 0' >> /etc/fstab

Answer

mkswap /dev/sdb1 && mkdir /data && swapon /dev/sdb1 && echo '/dev/sdb1 /data swap defaults 0 0' >> /etc/fstab

Question 14

Refer to the exhibit. The administrator wants to create a single file system that spans the entire 20 GB disk /dev/sdb. All data on the disk can be discarded. Which steps are required to create an XFS file system on the whole disk?

Accepted Answer

Run mkfs.xfs -f /dev/sdb; it will force creation of XFS on the whole disk without partition table.. An XFS file system can be created directly on a whole block device (e.g., mkfs.xfs -f /dev/sdb). This is a valid method and does not require a partition table. Creating a partition first (option D) is an acceptable alternative, but not the only required set of steps. The original explanation incorrectly states that a partition is required.

Answer

Run mkfs.xfs /dev/sdb directly; it will overwrite the partition table and create a file system.

Answer

Use pvcreate /dev/sdb, then vgcreate, lvcreate, and format the logical volume with mkfs.xfs.

Question 15

Put the steps to configure a cron job that runs a script every day at 2:30 AM in the correct order.

Accepted Answer

Edit the crontab file with 'crontab -e', add the line '30 2 * * * /path/to/script', then save and exit.. The standard method is to use `crontab -e` to edit the current crontab and add the line `30 2 * * * /path/to/script`. However, an equally valid method is to create a file containing that line and run `crontab <filename>` to install it as the crontab. Both methods are accepted on Red Hat systems. Therefore both A and B are correct.

Answer

Save and exit the crontab file first, then edit it again to add the line '30 2 * * * /path/to/script'.

Answer

Exit the crontab editor immediately, then edit the file again with 'crontab -e' and add the line '30 2 * * * /path/to/script'.

Question 16

Match each command to its function in managing storage.

Accepted Answer

fdisk: Manipulate disk partition table. The correct matches are: fdisk for partition table manipulation, mkfs for filesystem creation, mount for attaching filesystems, and lvcreate for logical volume creation. Common confusions include associating df or du with filesystem creation, and confusing lvcreate with display commands.

Answer

df: Create a filesystem

Answer

lvcreate: Display disk usage

Question 17

A junior administrator needs to create a new Ext4 file system on the device /dev/sdb1. Which command should be used?

Accepted Answer

mkfs.ext4 /dev/sdb1. The `mkfs.ext4` command is the standard utility for creating an ext4 filesystem on a block device. It formats the partition with the ext4 journaling filesystem, writing the superblock, inode table, and journal metadata. Option D is correct because it directly invokes the mke2fs program with the ext4 filesystem type.

Answer

fdisk /dev/sdb1

Answer

parted /dev/sdb1

Answer

tune2fs /dev/sdb1

Answer

fsck /dev/sdb1

Question 18

A system administrator needs to extend an existing logical volume 'lv_data' in volume group 'vg_data'. The administrator has already added a new physical volume /dev/sdd1 to the volume group. Which sequence of commands should be used to complete the extension and ensure the filesystem is usable?

Accepted Answer

lvextend -L +10G /dev/vg_data/lv_data; resize2fs /dev/vg_data/lv_data. After adding a physical volume to the volume group, the logical volume must be extended with `lvextend`, and then the filesystem must be resized with `resize2fs` to use the new space. The filesystem remains mounted and usable throughout; no remount or filesystem recreation is needed.

Answer

lvextend -L +10G /dev/vg_data/lv_data; mount /dev/vg_data/lv_data; resize2fs /dev/vg_data/lv_data

Answer

lvextend -L +10G /dev/vg_data/lv_data; mkfs.ext4 /dev/vg_data/lv_data

Answer

lvresize -L +10G /dev/vg_data/lv_data; fsck /dev/vg_data/lv_data

Answer

vgextend vg_data /dev/sdd1; lvextend -L +10G /dev/vg_data/lv_data; resize2fs /dev/vg_data/lv_data

Question 19

A logical volume 'lv_share' in volume group 'vg_share' has no free extents. The administrator needs to increase the size of '/dev/vg_share/lv_share' by 5 GB. There is another logical volume 'lv_archive' in the same volume group that has 10 GB free space within its filesystem. What must the administrator do to allocate space from 'lv_archive' to 'lv_share'?

Accepted Answer

Reduce the filesystem on 'lv_archive' with resize2fs, then reduce the logical volume with lvreduce, then extend 'lv_share'.. You must first shrink the filesystem on 'lv_archive' using resize2fs (or e2fsck -f / resize2fs) to free space within the filesystem, then reduce the logical volume with lvreduce to release the underlying physical extents back to the volume group. Only after those steps can you extend 'lv_share' with lvextend and then resize its filesystem. This sequence ensures data integrity and avoids filesystem corruption.

Answer

Shrink the filesystem on 'lv_archive' to free space, then use vgsplit to move the space to 'lv_share'.

Answer

Use lvreduce directly on 'lv_archive' without changing the filesystem, then lvextend on 'lv_share'.

Answer

Use lvresize to reduce 'lv_archive' and extend 'lv_share' in one command.

Answer

Add a new physical volume to the volume group instead.

Question 20

During boot, a custom application fails because the /data file system is not mounted. Upon investigation, the administrator sees an error 'UUID=abc123 not found' in the logs. Which command should the administrator use to correct the /etc/fstab entry?

Accepted Answer

blkid /dev/sdb1. The error 'UUID=abc123 not found' indicates that the /etc/fstab entry for /data references a UUID that does not match any block device. The administrator needs to find the correct UUID of the actual partition (e.g., /dev/sdb1) and update the fstab entry. The `blkid /dev/sdb1` command displays the UUID (and filesystem type) of that specific device, allowing the administrator to copy the correct UUID into /etc/fstab.

Answer

mount -a

Answer

xfs_info /dev/sdb1

Answer

fdisk -l /dev/sdb1

Answer

lsblk -f /dev/sdb1