[PLUG] Ubuntu 20.04 ZFS swap

[Tomas Kuchta]

Just a comment - if you are setting up swap file on zfs or btrfs - make
sure that you disable COW for the file/subvolume.

Tomas

On Wed, Jul 1, 2020, 15:01 Paul Heinlein <heinlein at madboa.com> wrote:

> On Wed, 1 Jul 2020, Robert Kopp wrote:
>
> > I wanted to try this amazing new file system, which is now one of the
> installation options for Focal. Unfortunately, I did not set up enough swap
> space for hibernation, which I would like. So I'm wondering if anyone could
> suggest a method of increasing swap space on my system, which appears below.
> > I have plenty of USB ports, so I would even be open to using a flash
> drive for this purpose. I note that it seems anxious to grab my external
> storage device, so perhaps it would resume from something more appropriate.
> >
> > Filesystem                                        1K-blocks       Used
> Available Use% Mounted onudev
> 16315052          0   16315052   0% /dev
> > tmpfs                                               3278412
> 2136    3276276   1% /run
> > rpool/ROOT/ubuntu_4uu5jb                          450678784    4601088
> 446077696   2% /
> > tmpfs                                              16392060     250784
> 16141276   2% /dev/shm
> > tmpfs                                                  5120
> 4       5116   1% /run/lock
> > tmpfs                                              16392060          0
> 16392060   0% /sys/fs/cgroup
> > bpool/BOOT/ubuntu_4uu5jb                            1517056
> 276096    1240960  19% /boot
> > rpool/ROOT/ubuntu_4uu5jb/var/games                446077824        128
> 446077696   1% /var/games
> > rpool/ROOT/ubuntu_4uu5jb/var/snap                 446077952        256
> 446077696   1% /var/snap
> > rpool/USERDATA/robert_xnnmf3                      452219392    6141696
> 446077696   2% /home/robert
> > rpool/ROOT/ubuntu_4uu5jb/var/mail                 446077824        128
> 446077696   1% /var/mail
> > rpool/ROOT/ubuntu_4uu5jb/srv                      446077824        128
> 446077696   1% /srv
> > rpool/ROOT/ubuntu_4uu5jb/var/lib                  447230720    1153024
> 446077696   1% /var/lib
> > rpool/ROOT/ubuntu_4uu5jb/var/lib/NetworkManager   446077952        256
> 446077696   1% /var/lib/NetworkManager
> > rpool/ROOT/ubuntu_4uu5jb/var/www                  446077824        128
> 446077696   1% /var/www
> > rpool/ROOT/ubuntu_4uu5jb/var/spool                446077952        256
> 446077696   1% /var/spool
> > /dev/sda1                                            523248
> 21268     501980   5% /boot/efi
> > rpool/ROOT/ubuntu_4uu5jb/var/log                  446102400      24704
> 446077696   1% /var/log
> > rpool/ROOT/ubuntu_4uu5jb/usr/local                446077824        128
> 446077696   1% /usr/local
> > rpool/USERDATA/root_xnnmf3                        446078208        512
> 446077696   1% /root
> > rpool/ROOT/ubuntu_4uu5jb/var/lib/AccountsService  446077824        128
> 446077696   1% /var/lib/AccountsService
> > rpool/ROOT/ubuntu_4uu5jb/var/lib/dpkg             446125184      47488
> 446077696   1% /var/lib/dpkg
> > rpool/ROOT/ubuntu_4uu5jb/var/lib/apt              446144768      67072
> 446077696   1% /var/lib/apt
>
> If you want to use your rpool, and you've got the space to spare,
> here's one way to go about it. This is for a 4GB swap partition.
>
> # create a zfs filesystem, with compression (optional)
> zfs create -V 4G -b 4096 \
>    -o compression=lz4 -o logbias=throughput -o sync=always \
>    -o primarycache=metadata -o secondarycache=none \
>    rpool/swap
>
> # make it into swap fs
> mkswap -f /dev/zvol/rpool/swap
>
> # turn it on
> swapon /dev/zvol/rpool/swap
>
> --
> Paul Heinlein
> heinlein at madboa.com
> 45°38' N, 122°6' W_______________________________________________
> PLUG mailing list
> PLUG at pdxlinux.org
> http://lists.pdxlinux.org/mailman/listinfo/plug
>