2022-04-04 20:45:58 +00:00
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## Basic setup
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1. Install `zfs-dracut`
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2. Set `mountpoint=/` for your root dataset (for compatibility, `legacy` also works, but is not recommended for new installations):
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```sh
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zfs set mountpoint=/ pool/dataset
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```
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3. Either (a) set `bootfs=` on the pool to the dataset:
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```sh
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zpool set bootfs=pool/dataset pool
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```
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4. Or (b) append `root=zfs:pool/dataset` to your kernel cmdline.
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5. Re-generate your initrd and update it in your boot bundle
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Encrypted datasets have keys loaded automatically or prompted for.
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If the root dataset contains children with `mountpoint=`s of `/etc`, `/bin`, `/lib*`, or `/usr`, they're mounted too.
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## cmdline
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1. `root=` | Root dataset is… |
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---------------------------|----------------------------------------------------------|
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*(empty)* | the first `bootfs=` after `zpool import -aN` |
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`zfs:AUTO`, `zfs:`, `zfs` | *(as above, but overriding other autoselection methods)* |
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`ZFS=pool/dataset` | `pool/dataset` |
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`zfs:pool/dataset` | *(as above)* |
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All `+`es are replaced with spaces (i.e. to boot from `root pool/data set`, pass `root=zfs:root+pool/data+set`).
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The dataset can be at any depth, including being the pool's root dataset (i.e. `root=zfs:pool`).
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`rootfstype=zfs` is equivalent to `root=zfs:AUTO`, `rootfstype=zfs root=pool/dataset` is equivalent to `root=zfs:pool/dataset`.
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2. `spl_hostid`: passed to `zgenhostid -f`, useful to override the `/etc/hostid` file baked into the initrd.
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3. `bootfs.snapshot`, `bootfs.snapshot=snapshot-name`: enables `zfs-snapshot-bootfs.service`,
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which creates a snapshot `$root_dataset@$(uname -r)` (or, in the second form, `$root_dataset@snapshot-name`)
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after pool import but before the rootfs is mounted.
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Failure to create the snapshot is noted, but booting continues.
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4. `bootfs.rollback`, `bootfs.rollback=snapshot-name`: enables `zfs-snapshot-bootfs.service`,
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which `-Rf` rolls back to `$root_dataset@$(uname -r)` (or, in the second form, `$root_dataset@snapshot-name`)
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after pool import but before the rootfs is mounted.
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Failure to roll back will fall down to the rescue shell.
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This has obvious potential for data loss: make sure your persistent data is not below the rootfs and you don't care about any intermediate snapshots.
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5. If both `bootfs.snapshot` and `bootfs.rollback` are set, `bootfs.rollback` is ordered *after* `bootfs.snapshot`.
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6. `zfs_force`, `zfs.force`, `zfsforce`: add `-f` to all `zpool import` invocations.
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May be useful. Use with caution.
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