zfs external backup drive with snapshot and encryption

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Get device id

$ ls /dev/disk/by-id -alh
...
lrwxrwxrwx 1 root root  10 okt 24 06:06 ata-WDC_WD10EZEX-08M2NA0_WD-WMC3F1471486-part4 -> ../../sda4
...

For example, I’m going to use /dev/disk/by-id/ata-WDC_WD10EZEX-08M2NA0_WD-WMC3F1471486-part4

Setup disk encryption with LUKS

setup LuKS

$ sudo apt install cryptsetup
$ cryptsetup luksFormat --cipher aes-xts-plain64 --key-size 512 --iter-time 10000 --use-random -y /dev/disk/by-id/ata-WDC_WD10EZEX-08M2NA0_WD-WMC3F1471486-part4

• --cipher encryption algorithm
• --key-size encryption key size
• --iter-time Number of millisecond to spend P8KDF passphrase processing
• --use-random use /dev/random
• -y verify passphrase

Disk device can now be opened.

$ sudo cryptsetup luksOpen /dev/disk/by-id/ata-WDC_WD10EZEX-08M2NA0_WD-WMC3F1471486-part4 luks1

Create new zfs pool

$ sudo zpool create ext-backup /dev/mapper/luks1

Create initial snapshot

Example i have data set tank/ROOT/home

$ sudo zfs snapshot tank/ROOT/home@ext-backup

Send the backup

$ sudo zfs send tank/ROOT/home@ext-backup | pv | sudo zfs recv ext-backup/home

Or with incremental-backup

$ sudo zfs snapshot tank/ROOT/home@ext-backup20180101
$ sudo zfs send -R -i tank/ROOT/home@ext-backup tank/ROOT/home@ext-backup20180101 | sudo zfs recv ext-backup/hom

A good idea is to set the external drive to be read-only

$ sudo zfs set readonly=on ext-backup

Safely close and remove external drive

After finished sending the snapshot, close the disk and export the pool

$ sudo zpool export ext-backup
$ sudo cryptsetup luksClose ext-backup

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