# ZFS

How to setup zfs on 64 bit arm boards.

*Note: this is wholly untested and likely to be broken on 32 bit arm boards*

## Initial Install / Setup

``` bash 

apt-add-repository universe
apt install zfs-dkms spl-dkms zfsutils-linux
cat > /etc/modprobe.d/zfs.conf <<EOF
# Minimize RAM pain
#options zfs zfs_arc_max=268435456 zfs_arc_meta_limit=201326592
options zfs zfs_arc_max=134217728 zfs_arc_meta_limit=67108864
#options zfs zfs_arc_max=100663296 zfs_arc_meta_limit=50331648
EOF

```

## Disk Setup and Pool Creation

Partition the disk and setup the zfs pool with basic settings

``` bash

parted /dev/disk/by-id/ata-Samsung_Portable_SSD_T5_S3UKNP0K601164R
  mklabel gpt
  mkpart
zpool create -o ashift=12 \
     -O copies=2 \
     -O atime=off -O compression=lz4 \
     -O normalization=formD \
     tank \
       /dev/disk/by-id/usb-JMicron_Tech_0000000055A1-0\:0-part1

zpool status

cat /sys/module/zfs/parameters/zfs_arc_max
cat /sys/module/zfs/parameters/zfs_arc_meta_limit

```

## zfs Backed Swap

Move swap from zram to zfs volumes on disk

``` bash

zfs create tank/swap
zfs create -V 1G -b $(getconf PAGESIZE) -o compression=zle \
      -o logbias=throughput -o sync=always \
      -o primarycache=metadata -o secondarycache=none \
      -o com.sun:auto-snapshot=false tank/swap/swap.1
zfs create -V 1G -b $(getconf PAGESIZE) -o compression=zle \
      -o logbias=throughput -o sync=always \
      -o primarycache=metadata -o secondarycache=none \
      -o com.sun:auto-snapshot=false tank/swap/swap.2

mkswap -f /dev/zvol/tank/swap/swap.1
mkswap -f /dev/zvol/tank/swap/swap.2
echo /dev/zvol/tank/swap/swap.1 none swap defaults 0 0 >> /etc/fstab
echo /dev/zvol/tank/swap/swap.2 none swap defaults 0 0 >> /etc/fstab
swapon -af

nano -w /etc/fstab # Add above swap and remove exiting ones

nano -w /etc/default/armbian-zram-config
    # Disabe if NOT using /var/log in RAM

```

## Regular scrubs and integrity checks

``` bash

crontab -e
22 0 14 * * /sbin/zpool scrub tank

```

## Bulk storage and Samba filesystem shares

``` bash

# Samba toolchain
apt install samba tdb-tools

# Samba user setup
useradd -g users -s /usr/sbin/nologin [username]
passwd [username]
smbpasswd -a [username]

nano -w /etc/samba/smb.conf
workgroup = non-default
comment out all share definitions

systemctl restart smbd

# Bulk storage for all the things
zfs create -o sharesmb=on tank/downloads
zfs create -o sharesmb=on tank/scratch

cat /var/lib/samba/usershares/*

```