diff --git a/README.md b/README.md index 4574302..a714bf2 100644 --- a/README.md +++ b/README.md @@ -32,10 +32,27 @@ Get started like so: In `pacman` on every `PreTransaction`, meaning right before any actual operation on a package begins, we trigger a ZFS snapshot. By default we identify the active system dataset by doing `findmnt / --noheadings --output source`. If exactly one source returns that is the exact name of a ZFS dataset in an imported zpool we create a snapshot on it. If no source returns we silently exit. If more than one source returns we raise an error and halt the `pacman` transaction. -We retain two different snapshot chains, one for `pacman` transactions that only affect what we are calling _trivial_ packages and a separate chain for _important_ packages. By default only the exact regular expression package name match `^(linux)$` is considered important. Whenever an important package is affected by a transaction a snapshot goes into the corresponding chain. In all other cases - when an important package is not affected - snapshots go into the trivial chain. +We retain two different snapshot chains, one for `pacman` transactions that only affect what we are calling _trivial_ packages and a separate chain for _important_ packages. By default only the exact regular expression package name match `^(linux|systemd|zfs-(dkms|utils))$` is considered important. Whenever an important package is affected by a transaction a snapshot goes into the corresponding chain. In all other cases - when an important package is not affected - snapshots go into the trivial chain. The _trivial_ snapshot chain by default keeps 15 snapshots, the _important_ chain keeps 5. The thought process here is that you will likely not futz around with a kernel every day whereas you may very well install arbitrary packages multiple times a day. Snapshots should keep you safe for a couple of days hence the defaults of 5 and 15 snapshots, respectively. +Snapshots may look like so: +``` +$ zfs list -o name -t all +NAME ┌─── Important because systemd +zpool | is on our list of +zpool/root | important packages +zpool/root/archlinux ▼▼▼ +zpool/root/archlinux@pacman_2023-03-07-0113_op:upgr_sev:imp_pkgs:systemd:bind:enchant:grep +zpool/root/archlinux@pacman_2023-03-07-0113_op:upgr_sev:trv_pkgs:jdk17-temurin +zpool/root/archlinux@pacman_2023-03-07-0115_op:upgr_sev:trv_pkgs:proton-ge-custom-bin + ▲▲▲▲ ▲▲▲ + | | +Pacman operation that triggered this snapshot ───┘ | + | +Severity based on affected packages, here trivial ───────┘ +``` + You may optionally include more ZFS datasets in this snapshot mechanism. Have a look at `pacman-zfs-snapshot.conf`, its comments should be clear enough to get you going. # Development