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DRACUT.ZFS(7) Miscellaneous Information Manual DRACUT.ZFS(7) NAME dracut.zfs -- overview of ZFS dracut hooks SYNOPSIS parse-zfs.sh -> dracut-cmdline.service | v | | v \-----------------> dracut-initqueue.service | zfs-import-opts.sh zfs-load-module.service v | | | | sysinit.target v | v | | zfs-import-scan.service v zfs-import-scan.service v v | zfs-import-cache.service | zfs-import-cache.service basic.target | | \__________________| | v v v | zfs-load-key.sh zfs-env-bootfs.service | | v v v zfs-import.target -> dracut-pre-mount.service | ^ | | dracut-zfs-generator | | _____________________/| |/ v | sysroot.mount <------- dracut-zfs-generator | | | v | initrd-root-fs.target <--- zfs-nonroot-necessities.service | | | | v | v dracut-mount.service | zfs-snapshot-bootfs.service | | | v | v | zfs-rollback-bootfs.service | | | v | | /sysroot/{usr,etc,lib,&c.} <---------------------------------------/ | | | v | initrd-fs.target \______________________ | \| v export-zfs.sh initrd.target | | v v dracut-shutdown.service | v zfs-needshutdown.sh -> initrd-cleanup.service Compare dracut.bootup(7) for the full flowchart. DESCRIPTION Under dracut, booting with ZFS-on-/ is facilitated by a number of hooks in the 90zfs module. Booting into a ZFS dataset requires mountpoint=/ to be set on the dataset containing the root filesystem (henceforth "the boot dataset") and at the very least either the bootfs property to be set to that dataset, or the root= kernel cmdline (or dracut drop-in) argument to specify it. All children of the boot dataset with canmount=on with mountpoints matching /etc, /bin, /lib, /lib??, /libx32, and /usr globs are deemed essential and will be mounted as well. zfs-mount-generator(8) is recommended for proper functioning of the system afterward (correct mount properties, remounting, &c.). CMDLINE Standard root=zfs:dataset, root=ZFS=dataset Use dataset as the boot dataset. All pluses (`+') are replaced with spaces (` '). root=zfs:AUTO, root=zfs:, root=zfs, [root=] After import, search for the first pool with the bootfs property set, use its value as-if specified as the dataset above. rootfstype=zfs root=dataset Equivalent to root=zfs:dataset. rootfstype=zfs [root=] Equivalent to root=zfs:AUTO. rootflags=flags Mount the boot dataset with -o flags; cf. "Temporary Mount Point Properties" in zfsprops(7). These prop- erties will not last, since all filesystems will be re-mounted from the real root. debug If specified, dracut-zfs-generator logs to the journal. Be careful about setting neither rootfstype=zfs nor root=zfs:dataset -- other automatic boot selection methods, like systemd-gpt-auto-generator and systemd-fstab-generator might take precedent. ZFS-specific bootfs.snapshot[=snapshot-name] Execute zfs snapshot boot-dataset@snapshot-name before piv- oting to the real root. snapshot-name defaults to the current kernel re- lease. bootfs.rollback[=snapshot-name] Execute zfs rollback -Rf boot-dataset@snapshot-name before piv- oting to the real root. snapshot-name defaults to the current kernel re- lease. spl_hostid=host-id Use zgenhostid(8) to set the host ID to host-id; otherwise, /etc/hostid in- herited from the real root is used. zfs_force, zfs.force, zfsforce Appends -f to all zpool import invoca- tions; primarily useful in conjunction with spl_hostid=, or if no host ID was inherited. FILES parse-zfs.sh (cmdline) Processes spl_hostid=. If root= matches a known pattern, above, pro- vides /dev/root and delays the initqueue until zfs(4) is loaded, zfs-import-opts.sh (systemd environment generator) Turns zfs_force, zfs.force, or zfsforce into ZPOOL_IMPORT_OPTS=-f for zfs-import-scan.service or zfs-import-cache.service. zfs-load-key.sh (pre-mount) Loads encryption keys for the boot dataset and its essential descen- dants. keylocation=prompt Is prompted for via systemd-ask-password thrice. keylocation=https://URL, keylocation=http://URL network-online.target is started be- fore loading. keylocation=file://path If path doesn't exist, udevadm is settled. If it still doesn't, it's waited for for up to 10s. zfs-env-bootfs.service (systemd service) After pool import, sets BOOTFS= in the systemd environment to the first non-null bootfs value in iteration order. dracut-zfs-generator (systemd generator) Generates sysroot.mount (using rootflags=, if any). If an explicit boot dataset was specified, also generates essential mountpoints (sysroot-etc.mount, sysroot-bin.mount, &c.), otherwise generates zfs-nonroot-necessities.service which mounts them explicitly after /sysroot using BOOTFS=. zfs-snapshot-bootfs.service, zfs-rollback-bootfs.service (systemd services) Consume bootfs.snapshot and bootfs.rollback as described in "CMDLINE". Use BOOTFS= if no explicit boot dataset was specified. zfs-needshutdown.sh (cleanup) If any pools were imported, signals that shutdown hooks are required. export-zfs.sh (shutdown) Forcibly exports all pools. /etc/hostid, /etc/zfs/zpool.cache, /etc/zfs/vdev_id.conf (regular files) Included verbatim, hostonly. mount-zfs.sh (mount) Does nothing on systemd systems (if dracut-zfs-generator succeeded). Otherwise, loads encryption key for the boot dataset from the console or via plymouth. It may not work at all! SEE ALSO dracut.bootup(7), zfsprops(7), zpoolprops(7), dracut-shutdown.service(8), systemd-fstab-generator(8), systemd-gpt-auto-generator(8), zfs-mount-generator(8), zgenhostid(8) FreeBSD Ports 14.quarterly March 28, 2023 DRACUT.ZFS(7)
NAME | SYNOPSIS | DESCRIPTION | CMDLINE | FILES | SEE ALSO
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