ContextAn LVM-backed filesystem is filling up.

Objective: Increase the storage capacity of the LVM-backed filesystem mounted at /var/log by approximately 0.2 GB, using free space from the existing volume group system, without unmounting the filesystem or interrupting access to existing log files.

The solution requires two operations:

Extend the logical volume using lvextend.

Grow the filesystem online so that it can use the additional capacity.

For the ext4 filesystem demonstrated in the video, the principal commands are:

sudo lvextend -L +0.2G /dev/system/log

sudo resize2fs /dev/system/log

The commands must be executed in the correct order. The first expands the underlying logical volume, while the second expands the ext4 filesystem. Both operations can be performed without unmounting a supported ext4 filesystem.

Linux manual page

+1

Step 1: Connect to the correct Linux server.

The video identifies the required host as lfcs00093.

From the candidate terminal, execute:

ssh lfcs00093

This establishes an SSH session with the server containing the LVM-backed /var/log filesystem.

All subsequent commands must be executed on this host.

Step 2: Verify that /var/log is a separate mounted filesystem.

Execute:

findmnt /var/log

This displays the source device, filesystem type, mountpoint and mount options.

For a more concise result:

findmnt -no SOURCE,FSTYPE,TARGET /var/log

The recording identifies the logical volume as:

/dev/system/log

The mountpoint is:

/var/log

This matters because /var/log could otherwise simply be a directory inside the root filesystem. The task specifically concerns a separate LVM-backed filesystem mounted there.

Step 3: Inspect the existing filesystem capacity.

Execute:

df -hT /var/log

This reports:

Filesystem device.

Filesystem type.

Total filesystem capacity.

Used space.

Available space.

Utilization percentage.

Mountpoint.

Record the existing size before extending the volume.

Step 4: Inspect the LVM configuration.

Execute:

sudo pvs

sudo vgs

sudo lvs

These commands provide three levels of LVM information:

Command

Information displayed

pvs

Physical volumes contributing disk capacity

vgs

Volume groups and their available space

lvs

Logical volumes and their current sizes

Confirm that the volume group system contains the logical volume log.

Step 5: Verify the logical volume directly.

Execute:

sudo lvdisplay /dev/system/log

Inspect the logical volume name, volume group, current size, logical extent allocation and status.

The logical volume must belong to:

system

And its name must be:

log

You can also execute:

sudo lvs /dev/system/log

This provides a concise overview.

Step 6: Check available free capacity in the volume group.

Execute:

sudo vgs system

For specific fields:

sudo vgs -o vg_name,vg_size,vg_free,vg_extent_size system

The VFree value must be sufficient to allocate the requested extension.

LVM allocates storage in units called physical extents. Consequently, an extension requested as 0.2G may be rounded to an appropriate extent boundary.

Do not add a new disk or create another volume group. The question requires using available capacity from the existing volume group system.

Step 7: Confirm the filesystem type before resizing.

Execute:

findmnt -no FSTYPE --mountpoint /var/log

The filesystem type determines which utility must be used to expand it.

Filesystem

Online expansion command

ext4

resize2fs /dev/system/log

XFS

xfs_growfs /var/log

The commands demonstrated for this task use resize2fs, which is appropriate for ext4.

Important: Do not run resize2fs against XFS or xfs_growfs against ext4.

Step 8: Check the size of the logical volume before modification.

Execute:

sudo lvs -o lv_name,vg_name,lv_size --units m /dev/system/log

This displays the current logical volume capacity in MiB.

For example, the original volume might have a size of 96 MiB. That is an illustrative starting point; use the actual value reported by the server.

You should record the initial capacity to verify the increase afterward.

Step 9: Extend the logical volume by 0.2 GB.

Execute:

sudo lvextend -L +0.2G /dev/system/log

This is the principal LVM expansion command.

sudo executes the command with administrative privileges.

lvextend increases the capacity of an existing logical volume.

-L specifies the capacity adjustment.

+0.2G requests an additional 0.2 GiB, subject to LVM's extent allocation.

/dev/system/log is the existing logical volume.

The plus sign is essential.

Compare:

sudo lvextend -L +0.2G /dev/system/log

with:

sudo lvextend -L 0.2G /dev/system/log

The first command adds capacity to the existing logical volume.

The second requests an absolute resulting size of 0.2 GiB, which would not correctly implement the task's requirement.

The official LVM documentation confirms that + makes the size relative to the current logical volume capacity.

Linux manual page

Step 10: Understand the effect of LVM extent allocation.

LVM allocates logical volume storage in physical extents.

For example, if the existing volume was 96 MiB and the requested increase was 0.2 GiB:

0.2

×

1024

=

204.8

MiB

0.2×1024=204.8 MiB

If the volume group uses 4 MiB physical extents, LVM may round the increase upward to 208 MiB.

The resulting size would then be:

96

+

208

=

304

MiB

96+208=304 MiB

This illustrates why the final capacity may differ slightly from the mathematical increase.

Such rounding is normal and does not indicate that LVM incorrectly extended the volume.

Step 11: Verify that the logical volume extension succeeded.

After the command completes, execute:

sudo lvs /dev/system/log

For more detailed output:

sudo lvdisplay /dev/system/log

Confirm that the logical volume has increased by the requested approximate capacity.

Also verify that the volume group has allocated free extents to the extended logical volume:

sudo vgs system

Important: The block device may now have additional capacity, but the filesystem itself may still show its previous size.

This is expected when lvextend is run without its filesystem-resizing option.

Step 12: Extend the ext4 filesystem without unmounting.

For the ext4 filesystem, execute:

sudo resize2fs /dev/system/log

This is the second essential command.

resize2fs expands or resizes ext2, ext3 and ext4 filesystems.

/dev/system/log specifies the logical volume containing the filesystem.

No explicit size is given, so resize2fs expands the filesystem to occupy the available device capacity.

On a supported modern Linux kernel, ext4 supports online expansion while mounted.

The official resize2fs(8) manual explicitly confirms that mounted ext4 filesystems can be expanded online.

Linux manual page

Step 13: Examine the filesystem expansion output.

An illustrative successful output might be:

resize2fs 1.46.5

Filesystem at /dev/system/log is mounted on /var/log; on-line resizing required

The filesystem on /dev/system/log is now 77824 (4k) blocks long.

The version, block count and other details will vary.

The critical points are that online resizing is performed and the command completes successfully.

Immediately check the command's exit status:

echo $?

Expected:

0

If resize2fs reports an error, diagnose it rather than running lvextend again. The logical volume may already have been extended successfully, and a second lvextend would request additional capacity beyond the task's requirement.

Step 14: Verify the new filesystem capacity.

Execute:

df -hT /var/log

The filesystem's total size should now reflect the extended logical volume.

To inspect the size using MiB units:

df -BM /var/log

Compare the result against the initial measurement taken before performing the extension.

There may be a small difference between logical volume capacity and usable filesystem space because the filesystem maintains its own metadata and reserved structures.

Step 15: Verify that /var/log remains mounted.

Execute:

findmnt --mountpoint /var/log

The command should identify the same filesystem mounted at:

/var/log

You can also execute:

mount | grep ' on /var/log '

The task states:

Without unmounting the LVM-backed filesystem mounted at /var/log

Therefore, do not execute:

sudo umount /var/log

Unnecessary unmounting could interrupt running services and would violate the task.

Step 16: Verify the filesystem remains accessible.

Execute:

ls -ld /var/log

Then:

sudo ls -la /var/log

Confirm that the directory and its existing log files remain accessible.

There is no requirement to delete logs, format the filesystem, or recreate the mount.

Do not execute commands such as:

sudo mkfs.ext4 /dev/system/log

That command creates a new filesystem and would risk destroying existing data.

The task requires expanding the current filesystem, not recreating it.

Step 17: Alternative method using automatic filesystem expansion.

LVM also provides the option:

sudo lvextend -r -L +0.2G /dev/system/log

The -r or --resizefs option requests that the filesystem be resized along with the logical volume.

This can simplify the procedure when the installed LVM filesystem tooling supports the mounted filesystem's online expansion.

The official LVM documentation describes --resizefs as resizing the underlying filesystem together with the logical volume.

Linux manual page

However, do not execute this alternative after already running the two-command solution. Doing so would request another 0.2 GiB increase.

For this question, the explicit two-command procedure is preferable because each stage can be inspected separately:

sudo lvextend -L +0.2G /dev/system/log

sudo resize2fs /dev/system/log

Step 18: Confirm that no unnecessary storage changes were made.

The task does not require:

Creating a new logical volume.

Adding a physical disk.

Creating another volume group.

Modifying unrelated logical volumes.

Unmounting /var/log.

Reformatting the filesystem.

Rebooting the server.

Avoid commands such as:

sudo lvcreate

sudo vgcreate

sudo mkfs.ext4

sudo umount /var/log

These operations are not needed for the requested online expansion.

Step 19: Perform final verification.

Execute:

sudo lvs /dev/system/log

df -hT /var/log

findmnt --mountpoint /var/log

The completed task must satisfy the following:

Requirement

Expected result

Correct host

lfcs00093

Volume group

system

Logical volume

log

Mountpoint

/var/log

Requested increase

Approximately 0.2 GiB

Logical volume extended

Yes

Filesystem expanded

Yes

Filesystem unmounted

No

Existing data preserved

Yes

Filesystem accessible

Yes

Final Solution

The essential command sequence for the ext4 filesystem is:

# Connect to the designated server

ssh lfcs00093

# Verify the filesystem mount

findmnt --mountpoint /var/log

# Record the current filesystem size

df -hT /var/log

# Inspect the volume group and logical volume

sudo vgs system

sudo lvs /dev/system/log

# Confirm the filesystem is ext4

findmnt -no FSTYPE --mountpoint /var/log

# Extend the logical volume by 0.2G

sudo lvextend -L +0.2G /dev/system/log

# Expand the ext4 filesystem online

sudo resize2fs /dev/system/log

# Verify the new logical volume size

sudo lvs /dev/system/log

# Verify filesystem expansion

df -hT /var/log

# Confirm the filesystem remains mounted

findmnt --mountpoint /var/log

Technical Verification and References

The solution has been checked against the relevant official Linux storage manuals:

LVM lvextend(8)

— Documents relative logical volume expansion using the + prefix and the optional filesystem-resizing feature.

Linux resize2fs(8)

— Documents online ext4 filesystem expansion.

Linux xfs_growfs(8)

— Documents the corresponding online expansion utility for XFS.

Video review: The demonstrated procedure uses lvextend to increase the logical volume and resize2fs to grow the filesystem. That is the correct operational sequence for a mounted ext4 filesystem. The commands should be considered successfully verified on the target host only after their exit statuses, updated capacity and mounted state are checked.

Expected result: The existing LVM-backed filesystem at /var/log has approximately 0.2 GiB of additional capacity allocated from the system volume group. The filesystem is expanded online and remains mounted and accessible throughout the operation.

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