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Category: ZFS

ZFS Filesystem

LXC, ZFS

[ZFS] Rollback LXC

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Look for a specific snapshot of your LXC.

sudo zfs list -rt snapshot | grep data/lxc/subvol-101

I just want to rollback 2 hours, so I choose the snapshot with timestamp 2019-12-05-1117.

...
data/lxc/subvol-110-disk-0@zfs-auto-snap_hourly-2019-12-05-0917   11,7M      -     24,2G  -
data/lxc/subvol-110-disk-0@zfs-auto-snap_hourly-2019-12-05-1017   11,9M      -     24,2G  -
data/lxc/subvol-110-disk-0@zfs-auto-snap_hourly-2019-12-05-1117   11,7M      -     24,2G  -
data/lxc/subvol-110-disk-0@zfs-auto-snap_hourly-2019-12-05-1217   11,8M      -     24,2G  -
data/lxc/subvol-110-disk-0@zfs-auto-snap_hourly-2019-12-05-1317   12,1M      -     24,2G  -

If there are one or more snapshots between the current state and the snapshot you want to rollback to, you have to add -r (force deletion) to the rollback command.

sudo zfs rollback -r data/lxc/subvol-110-disk-0@zfs-auto-snap_hourly-2019-12-05-1117

ZFS

[ZFS] Encryption

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Native encryption in ZFS is supported since version 0.8.0. Check your current ZFS version with:

modinfo zfs

First activate the encryption feature on your pool:

zpool set feature@encryption=enabled pool_name

To get an overview of all pools with enabled encryption use the following command:

zpool get all | grep encryption

To create a new encrypted dataset with a passphrase:

zfs create -o encryption=aes-256-gcm -o keyformat=passphrase pool_name/dataset_name

Check the keystatus, the current encryption type and the mountpoint with the following commands:

zfs get keystatus pool_name/dataset_name
zfs get encryption pool_name/dataset_name
zfs list pool_name/dataset_name

Change the passphrase with:

zfs change-key pool_name/dataset_name

After a reboot you first have to load your key and then mount your dataset:

zfs load-key pool_name/dataset_name
zfs mount pool_name/dataset_name

Unmount and unload your key:

zfs umount pool_name/dataset_name
zfs unload-key pool_name/dataset_name

If you are sharing this dataset via NFS, it could be necessary to restart the NFS service after mounting. I just deactivate and activate again NFS on the dataset.

zfs set sharenfs=off pool_name/dataset_name
zfs set sharenfs=on pool_name/dataset_name
ZFS

[ZFS] Basic Commands

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Documentation: https://github.com/zfsonlinux/zfs/wiki/Admin-Documentation
Manual Pages: https://zfs.datto.com/man/
Milestones: https://github.com/zfsonlinux/zfs/milestones

modinfo zfs                               //check current ZFS version

zfs list                                  //list pool with datasets
zfs list -r pool                          //show all datasets in a pool with size and mountpoint
zfs list -r -o name,mountpoint,mounted    //check if datasets are mounted   

zpool status (pool)
zpool list
zpool list -v
zpool iostat (pool 1)
zpool iostat -v

Activate NFS on dataset:

zfs set sharenfs=on pool/dataset
zfs get sharenfs pool/dataset

Usefull comands when replacing a failed disk:

ls -l /dev/disk/by-id/                // Disk ID's
zdb                                   // Display zpool debugging and consistency information
smartctl -a /dev/ada0                 // S.M.A.R.T info
wipefs -a new_hdd                     // remove ext4 filesystem 
zpool replace data old_hdd new_hdd    // Replace HDD

Scrub cronjob: 

cat /etc/cron.d/zfsutils-linux

Add and remove Log & L2ARC:

zpool add data log sda1
zpool add data cache sda2

zpool remove data log sda1
zpool remove data cache sda2