= filesystems
== metadata

https://en.wikipedia.org/wiki/Comparison_of_file_systems

=== admissible characters for basenames

FAT32/FAT32X short-filename      [OEM] A-Z, 0-9, ! # $ % & ' ( ) - @ ^ _ ` { } ~, 0x80–0xFF, 0x20
FAT32/FAT32X long-filename       Unicode except NUL, " * / : < > ? \ |
NTFS (Win32)                     any case-insensitive UTF-16 code unit except /\:*"?<>| as well as NUL
NTFS (POSIX)                     any case-  sensitive UTF-16 code unit except / as well as NUL
ext2 & ext3 & ext4               any byte except NUL and I
ZFS                              any Unicode except NUL 
btrfs                            any byte except '/' and NUL

== operations
=== get filesystem size of current directory

du -sh .

=== estimate current FS usage

df -h

=== how to use shred

shred -s 80G -u -v -z

=== create a bootable Ubuntu USB stick

sudo mkfs.vfat /dev/sdd -I
sudo dd if=xubuntu-*-amd64.iso of=/dev/sdd bs=4MB;sync;eject /dev/sdd

== ZFS commands

zpool status
zpool create $POOLNAME /dev/$DEVICE
zpool list
zpool status $POOLNAME
zpool iostat $POOLNAME
zpool iostat $POOLNAME -v
zpool destroy $POOLNAME

zpool create $POOLNAME mirror /dev/$DEVICE1 /dev/$DEVICE2      # RAID-1
zpool create $POOLNAME raidz1 /dev/$DEVICE1 /dev/$DEVICE2 ...  # roughly RAID-5 (you can loose 1 disk)

zfs create $POOLNAME/$FSNAME    => cd /$POOLNAME/$FSNAME
zfs set readonly=on $POOLNAME/$FSNAME
zfs get all
zfs get creation,used $POOLNAME
zfs get quota
zfs set quota
zfs get reservation