EX200 Configure local storage Practice Test 6 — 15 Questions

Question 1

An administrator wants to add an additional swap partition of 2GB on device /dev/sdb1. Which set of commands should be used to enable swap and make it persistent across reboots?

Accepted Answer

mkswap /dev/sdb1; swapon /dev/sdb1; echo '/dev/sdb1 swap swap defaults 0 0' >> /etc/fstab. It follows the proper sequence to prepare and activate a swap partition on /dev/sdb1. First, `mkswap` initializes the partition as a swap area by writing a swap signature. Then `swapon` activates it immediately. Finally, adding an entry to /etc/fstab ensures the swap is automatically enabled at boot, making it persistent across reboots.

Answer

parted /dev/sdb set 1 swap on

Answer

swapadd /dev/sdb1

Answer

mkfs.ext4 /dev/sdb1; mount /dev/sdb1 /swap

Answer

None of the above

Question 2

Which three fields are present in every /etc/fstab entry? (Choose three.)

Accepted Answer

Mount point. Every /etc/fstab entry consists of six whitespace-separated fields: device, mount point, filesystem type, options, dump, and pass. Although dump and pass can be omitted and default to 0, the dump field is considered present in every entry due to its default value. The question asks for three fields that are present in every entry; these include the mount point (A), device (B), and dump field (C). The filesystem type (D) is also present, but the question requires exactly three choices, and the dump field is often overlooked. UUID (E) is not a separate field; it is a method to specify the device.

Answer

Filesystem type

Answer

UUID

Question 3

Refer to the exhibit. The /proc/mdstat output shows a RAID1 array with two devices. One of the disks (/dev/sda1) fails. Which sequence of commands would be used to remove the failed disk and add a new replacement disk /dev/sdc1?

Accepted Answer

mdadm /dev/md0 --fail /dev/sda1; mdadm /dev/md0 --remove /dev/sda1; mdadm /dev/md0 --add /dev/sdc1. It uses the proper mdadm syntax with the device name immediately after the command, followed by the action and the disk. The --fail flag marks the disk as faulty, --remove removes it from the array, and --add adds the new replacement disk. This sequence ensures the array remains in a degraded state before safely replacing the failed component.

Answer

mdadm --fail /dev/md0 /dev/sda1; mdadm --remove /dev/md0 /dev/sda1; mdadm --add /dev/md0 /dev/sdc1

Answer

mdadm /dev/md0 --set-faulty /dev/sda1; mdadm /dev/md0 --remove /dev/sda1; mdadm /dev/md0 --add /dev/sdc1

Answer

mdadm /dev/md0 --remove /dev/sda1; mdadm /dev/md0 --add /dev/sdc1

Answer

mdadm /dev/md0 --replace /dev/sda1 --with /dev/sdc1

Question 4

A Red Hat Enterprise Linux 9 server has an LVM volume group 'vg01' that contains two physical volumes: /dev/sda2 and /dev/sdb1. After a reboot, the system fails to activate the volume group. The administrator runs 'pvdisplay' and sees one physical volume as 'unknown device'. What is the most likely cause?

Accepted Answer

The LVM filter in /etc/lvm/lvm.conf is excluding /dev/sdb1. The LVM filter in /etc/lvm/lvm.conf controls which devices LVM scans during activation. If the filter excludes /dev/sdb1, LVM will not recognize that physical volume, causing the volume group to fail activation. The 'unknown device' status indicates LVM cannot access the device metadata, not that the device is missing or corrupted.

Answer

The physical volume is corrupted and needs to be restored from backup

Answer

The filesystem on the logical volume has become corrupted, preventing LVM metadata access

Answer

The UUID of the physical volume has changed due to a disk replacement

Question 5

A storage administrator is asked to increase the size of an ext4 filesystem mounted at /data. The underlying logical volume /dev/mapper/vg01-lv01 is currently 10GB and the volume group has 5GB of free extents. After extending the logical volume by 2GB using lvextend -L +2G /dev/mapper/vg01-lv01, what command must be run to resize the filesystem?

Accepted Answer

resize2fs /dev/mapper/vg01-lv01. After extending the logical volume with `lvextend`, the filesystem does not automatically recognize the new space. For ext4 filesystems, the `resize2fs` command must be run to resize the filesystem to use the additional logical volume capacity. This command can be executed online (while the filesystem is mounted) and will expand the filesystem to fill the available space in the logical volume.

Answer

lvextend -r -L +2G /dev/mapper/vg01-lv01

Answer

xfs_growfs /data

Answer

fsck -f /dev/mapper/vg01-lv01

Question 6

An administrator needs to add a 2GB swap partition to an existing disk (/dev/sdc) that already has one partition. The administrator creates a second primary partition using fdisk and sets the type to Linux swap (82). Which command completes the setup to enable swap?

Accepted Answer

mkswap /dev/sdc2 && swapon /dev/sdc2. After creating the partition with fdisk and setting the type to 82 (Linux swap), the partition must be formatted as a swap area using `mkswap` before it can be activated. The `swapon` command then enables the swap space. Option C correctly chains `mkswap /dev/sdc2` to initialize the swap signature and `swapon /dev/sdc2` to activate it.

Answer

swapon /dev/sdc2

Answer

mkfs.swap /dev/sdc2 && swapon /dev/sdc2

Answer

mkswap /dev/sdc && swapon /dev/sdc

Question 7

A technician is configuring a new Red Hat Enterprise Linux 9 server with multiple disks. They need to create a RAID 1 array using /dev/sda and /dev/sdb for the /boot partition. Which tool can create the RAID array and enable booting from it?

Accepted Answer

Use mdadm to create a RAID1 device and install GRUB on both disks. Mdadm is the standard Linux tool for creating software RAID arrays, including RAID 1 (mirroring). For the /boot partition, which must be readable by the bootloader, GRUB must be installed on both disks in the RAID 1 array to ensure bootability if one disk fails. mdadm creates the RAID device, and GRUB can then be installed on each disk's MBR or GPT partition.

Answer

Use parted to create a RAID array directly by specifying the RAID level

Answer

Use fdisk to create a RAID partition and then format with ext4

Answer

Use LVM to create a mirrored logical volume for /boot

Question 8

A system has a logical volume that is thinly provisioned. The thin pool has a size of 100GB and the thin volume has a virtual size of 500GB. The administrator notices that the thin pool has only 5GB of data written so far. Which command will display the current data usage of the thin volume?

Accepted Answer

lvs -o lv_name,data_percent. The `lvs -o lv_name,data_percent` command specifically displays the percentage of the thin pool that has been consumed by the thinly provisioned logical volume. For thin volumes, the `data_percent` field reports the actual data usage relative to the thin pool's capacity, which is exactly what the administrator needs to see the current 5GB usage against the 100GB pool.

Answer

df -h /dev/mapper/vg01-thinvol

Answer

lsblk /dev/mapper/vg01-thinvol

Answer

lvdisplay /dev/vg01/thinvol

Question 9

An administrator wants to mount an existing ext4 filesystem from /dev/sdb1 to /mnt/data at boot time. What entry should be added to /etc/fstab?

Accepted Answer

/dev/sdb1  /mnt/data  ext4  defaults  0  0. It specifies the correct device (/dev/sdb1), the correct mount point (/mnt/data), the correct filesystem type (ext4), and the correct mount options (defaults) for an ext4 filesystem to be mounted at boot. The /etc/fstab entry must include all six fields in order: device, mount point, filesystem type, options, dump, and pass.

Answer

/dev/sdb1  /mnt/data  xfs  defaults  0  0

Answer

LABEL=data  ext4  defaults  0  0

Answer

/dev/sdb1  /data  ext4  defaults  0  0

Question 10

A database server experiences high disk I/O wait times. The administrator runs 'iostat -x 1' and sees that the avgqu-sz for /dev/sda is 25 and await is 200 ms. The disk is a single 7200 RPM SATA drive. Which action is most likely to improve performance?

Accepted Answer

Replace the drive with an SSD or add additional drives in RAID 10. The high avgqu-sz (25) and await (200 ms) indicate the single 7200 RPM SATA drive is saturated, as its maximum IOPS is typically around 75-100 random I/O operations per second. Replacing it with an SSD (which can handle thousands of IOPS) or adding drives in RAID 10 (which increases IOPS through parallelism) directly addresses the hardware bottleneck. No software tuning can overcome the physical limitations of a single spinning disk under heavy I/O load.

Answer

Increase the read-ahead buffer using blockdev --setra

Answer

Change the I/O scheduler from CFQ to noop

Answer

Run 'fsck -f' on the filesystem to check for fragmentation

Question 11

An administrator attempts to mount an XFS filesystem from /dev/sdc1 to /mnt/archive but receives the error: 'mount: /mnt/archive: wrong fs type, bad option, bad superblock on /dev/sdc1, missing codepage or helper program, or other error.' The output of 'dumpe2fs /dev/sdc1' shows 'dumpe2fs: Bad magic number in super-block while trying to open /dev/sdc1'. What is the most likely problem?

Accepted Answer

The filesystem on /dev/sdc1 is XFS, not ext4. The error message 'wrong fs type' combined with 'dumpe2fs: Bad magic number in super-block' indicates that the filesystem on /dev/sdc1 is not an ext2/3/4 filesystem. dumpe2fs is designed to read ext2/3/4 superblocks, and the 'bad magic number' error means it cannot find a valid ext superblock. Since the administrator is trying to mount an XFS filesystem, the correct tool to examine it is xfs_db or xfs_info, not dumpe2fs. Therefore, the most likely problem is that the filesystem is XFS, not ext4.

Answer

The mount point /mnt/archive does not exist

Answer

The XFS kernel module is not loaded

Answer

The partition /dev/sdc1 does not exist

Question 12

An administrator wants to add 20GB of additional space to the root filesystem. The volume group vg01 has no free extents. Which action should be taken first?

Accepted Answer

Attach a new disk, create a physical volume on it, add it to vg01 with vgextend, then extend vg01-root. To extend the root filesystem when the volume group has no free extents, you must first add a new physical volume to the volume group. This involves attaching a new disk, creating a physical volume on it with `pvcreate`, adding it to vg01 with `vgextend`, and then using `lvextend` followed by `resize2fs` (or `xfs_growfs` for XFS) to extend the logical volume and filesystem. This sequence ensures the volume group has available extents before extending the logical volume.

Answer

Shrink the logical volume vg01-data and then extend vg01-root

Answer

Run vgextend vg01 /dev/sdc (assuming /dev/sdc is a new disk) but this command requires the PV to be created first

Answer

Use lvextend to extend the root logical volume into the free space of sdb1

Question 13

An administrator needs to mount the backup filesystem with the ‘exec’ option temporarily for a one-time script. Which command will remount the filesystem with exec without unmounting?

Accepted Answer

mount -o exec,remount /dev/sdc1 /mnt/backup. Both options B and C are valid commands to remount a filesystem with the exec option without unmounting. Option B specifies both the device and mount point, which is accepted by the mount command when using the remount option. Option C uses only the mount point, which is also sufficient. The remount option allows changing mount options on a live filesystem. Options A and D are invalid: A unmounts and remounts, which is not a single remount operation and could cause issues; D attempts to remount all filesystems with exec, which may not apply correctly and does not target the specific filesystem.

Answer

umount /mnt/backup && mount /mnt/backup

Answer

mount -a -o exec

Question 14

An administrator replaces a failed disk in a RAID 10 array /dev/md0. The new disk is /dev/sdc. The admin runs: mdadm /dev/md0 --add /dev/sdc. The command succeeds, but the array does not start rebuilding. What is the most likely reason?

Accepted Answer

The failed disk was not removed from the array first; you need to mark it as failed and remove it.. When a disk in a RAID array fails, the array marks it as faulty but does not automatically remove it. The administrator must first explicitly mark the failed disk as failed with `mdadm --fail` and then remove it with `mdadm --remove` before adding a replacement. Without removing the failed device, the array still considers the old disk as part of the array, and the new disk is not recognized as a replacement, so no rebuild starts.

Answer

The new disk must be partitioned with the same layout as the failed disk.

Answer

The --add command should have been --re-add instead.

Answer

The array is still clean and does not need the new disk yet.

Question 15

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.