Add option to have multi-filesystems (/home /var /root)

[ghfields]

From https://github.com/zfsonlinux/zfs/wiki/Ubuntu-18.04-Root-on-ZFS

zfs create -o setuid=off rpool/home zfs create -o mountpoint=/root rpool/home/root zfs create -o canmount=off -o setuid=off -o exec=off rpool/var zfs create -o com.sun:auto-snapshot=false rpool/var/cache zfs create -o acltype=posixacl -o xattr=sa rpool/var/log zfs create rpool/var/spool zfs create -o com.sun:auto-snapshot=false -o exec=on rpool/var/tmp

If you use /srv on this system: zfs create rpool/srv

If this system will have games installed: zfs create rpool/var/games

If this system will store local email in /var/mail: zfs create rpool/var/mail

If this system will use NFS (locking): zfs create -o com.sun:auto-snapshot=false -o mountpoint=/var/lib/nfs rpool/var/nfs

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From https://wiki.archlinux.org/index.php/ZFS zfs set sync=disabled /tmp