linuxexpert-practice-labs/labs/lfcs/3-3-filesystems/README.md

LFCS 3.3: Filesystems

Partitioning a disk, XFS and ext4 filesystems, labels and UUIDs, repairing a damaged filesystem, and growing a partition.

Before you start

The lab adds an empty 3 GiB spare disk, /dev/loop40. Its partitions show up as /dev/loop40p1, /dev/loop40p2 and so on. It comes back at every boot, before filesystems are mounted, so /etc/fstab lines for it keep working. The disk is a file, /var/lib/le-lab/disks/disk0.img, which task 4 grows the way a hypervisor would.

Tasks

1. Create a GPT partition table on /dev/loop40 and a 2 GiB partition, /dev/loop40p1, with an XFS filesystem labeled backup, mounted at /backup by label at every boot.
2. Create a second partition, /dev/loop40p2, filling the rest of the disk, with an ext4 filesystem. Reserve only 1% of it for root, and mount it at /data by UUID at every boot.
3. Damage the ext4 filesystem while it's unmounted, with sudo dd if=/dev/zero of=/dev/loop40p2 bs=4096 seek=10 count=50, then repair it.
4. Grow the disk to 4 GiB: sudo truncate -s 4G /var/lib/le-lab/disks/disk0.img, then sudo losetup -c /dev/loop40 so the system sees the new size. Then grow the last partition (the ext4 one) and its filesystem to fill the disk, while it's mounted.

Hints

• fdisk, gdisk or parted; lsblk, partprobe.
• mkfs.xfs -L, mkfs.ext4, tune2fs -m and tune2fs -l.
• blkid, lsblk -f; LABEL= and UUID= in /etc/fstab; findmnt --verify.
• umount, e2fsck -f; e2fsck -fn only reports.
• growpart (or parted resizepart), then resize2fs; df -h.