EX200 Configure local storage Practice Question
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?
⚠ Common exam trap
It's easy for candidates to assume all Linux filesystems use resize2fs, but EX200 tests the RHEL default of XFS, which requires xfs_growfs and a mount point argument, not a block device.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
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 analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
He should have used lvresize instead of lvextend.
Why it's wrong here
lvextend is a purpose-built command for increasing a logical volume's size, and it is perfectly valid on RHEL systems. lvresize is a more generic tool that can both extend and reduce LVs, but there is no requirement to use it; lvextend simply calls the same underlying resize logic. The verdict stands: the admin's error was not in choosing lvextend, but in using resize2fs to grow an XFS filesystem afterward.
- ✗
He forgot to run partprobe after pvcreate.
Why it's wrong here
pvcreate initializes a physical volume, but when run against a whole disk (e.g., /dev/sdb) it does not create or modify a partition table, so there is no partition-table change for the kernel to re-read and no partprobe is needed. partprobe is only necessary after fdisk/gdisk modify partition tables to inform the kernel of new partitions. Since the scenario involves adding a whole PV to the VG before lvextend, partprobe is irrelevant and would not affect filesystem resizing.
- ✗
The lvextend command failed because vg_system has no free extents.
Why it's wrong here
The senior admin explicitly added another PV to the vg_system volume group before running lvextend, which increases the VG's free extent count. If vg_system truly had no free extents, lvextend would fail with an 'insufficient free space' error and the LV size would not change. Yet the reported symptom is a full /var partition despite the LV being extended, meaning lvextend succeeded and the failure occurred at the filesystem-grow stage—using resize2fs on an XFS filesystem.
- ✓
He used resize2fs instead of xfs_growfs because /var is typically XFS.
Why this is correct
On RHEL 8 and RHEL 9, the default filesystem for /var (and other directories) is XFS, not ext4. After extending the logical volume, the filesystem must be grown to use the new space, and the proper command for that is xfs_growfs, not resize2fs—resize2fs only works on ext2/ext3/ext4 filesystems and will fail or do nothing against XFS. Therefore, the admin's use of resize2fs is exactly the mistake that would leave /var appearing full even though the LV was successfully expanded.
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