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Eliminate confusing examples that conflict with the root-on-ZFS HOWTO. See issue #8200.

Richard Laager 2018-12-10 12:00:10 -06:00
parent 4600190dcd
commit 8db080c30e
1 changed files with 2 additions and 24 deletions
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26
Debian-GNU-Linux-initrd-documentation.md

@ -51,42 +51,20 @@ Although there is currently no support for native encryption in ZFS On Linux, th
## Separated filesystems
### Descended filesystems
If there is separate filesystems (for example a separate dataset for each of <code>/usr</code>, <code>/var</code> etc), the snapshot boot code will try to find the snapshot under each of these filesystems and clone (or rollback) each of these.
If there are separate filesystems (for example a separate dataset for <code>/usr</code>), the snapshot boot code will try to find the snapshot under each filesystems and clone (or rollback) them.
Example:
```
rpool/ROOT/debian-1@some_snapshot
rpool/ROOT/debian-1/boot@some_snapshot
rpool/ROOT/debian-1/usr@some_snapshot
rpool/ROOT/debian-1/var@some_snapshot
```
These will create the following filesystems respectively (if not doing a rollback):
```
rpool/ROOT/debian-1_some_snapshot
rpool/ROOT/debian-1/boot_some_snapshot
rpool/ROOT/debian-1/usr_some_snapshot
rpool/ROOT/debian-1/var_some_snapshot
```
The initrd code will use the <code>mountpoint</code> option (if any) in the original (without the snapshot part) dataset to find _where_ it should mount the dataset. Or it will use the name of the dataset below the root filesystem (<code>rpool/ROOT/debian-1</code> in this example) for the mount point.
### Equal level filesystems
It is also possible to have all filesystems in the same 'level' as the root filesystems:
```
rpool/ROOT/root
rpool/ROOT/boot
rpool/ROOT/usr
rpool/ROOT/var
```
This, however, require the setting of the <code>ZFS_INITRD_ADDITIONAL_DATASETS</code> variable in the <code>/etc/default/zfs</code> file. They are mounted in the order of appearance in this variable, so take care not to enter a child before it's mother.
This layout does however not allow for automatic snapshot cloning and mounting.
Also, here the <code>mountpoint</code> property is **required** to know where to mount the dataset.
It does not matter (in both variants, _decedent_ or _equal_ filesystems if they're 'native' ZFS filesystems or legacy. The code will figure this out automatically. There is also no need for an entry in <code>/etc/fstab</code> for these filesystems.
The initrd code will use the <code>mountpoint</code> option (if any) in the original (without the snapshot part) dataset to find _where_ it should mount the dataset. Or it will use the name of the dataset below the root filesystem (<code>rpool/ROOT/debian-1</code> in this example) for the mount point.