Linux filesystems exam time:
section A basics
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what does CoW stand for?
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evaluate through pros and cons which you personally would pick: Btrfs, ZFS, F2FS, bcachefs, OverlayFS, aufs, Nilfs2, JFFS2, UBIFS
section B btefs
- what exactly happens when running this command, including how qgroups, compression, and recursion interact?
btrfs balance start -dusage=5 -musage=20 -c zstd \
--bg /srv/vms && \
btrfs qgroup limit 50G /srv/vms/guests/win10
- explain the effect of the following command on device allocation, RAID reshaping, and metadsta distribution:
btrfs device add -f /dev/nvme2n1 /home && \
btrfs balance start -mconvert=raid1 -dconvert=raid1 -sconvert=dup /home
- describe what this snapshotting pipeline does, including send stream structure, parent selection, and how receive-side overwrites are handled:
btrfs subvolume snapshot -r /opt/app /opt/.snaps/auto-$(date +%s) && \
btrfs send -c -p /opt/.snaps/last-full \
/opt/.snaps/auto-$(date +%s) \
| ssh backup 'btrfs receive -f /backup/opt/incoming'
- what actions occur on the filesystem when this defrag call is executed, especially regarding extent sharing and how compression interacts?
btrfs filesystem defrag -r -v -czstd:15 \
/var/lib/docker/overlay2
- analyze subvolume management sequence, including how default-subvolume selection influences mount behavior:
btrfs subvolume delete /mnt/root/@old && \
btrfs subvolume snapshot -r /mnt/root/@clean /mnt/root/@ && \
btrfs subvolume set-default 256 /mnt/root
section C zfs
[...]
/s