From 72c3e524beb6239fdd52a3f59dabc8f791a20650 Mon Sep 17 00:00:00 2001 From: Jackson Date: Fri, 21 Nov 2025 05:00:24 +0100 Subject: [PATCH] docs: btrfs: note that btrfs hook doesn't cache even with runtime dir --- docs/reference/configuration/data-sources/btrfs.md | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/docs/reference/configuration/data-sources/btrfs.md b/docs/reference/configuration/data-sources/btrfs.md index 24ec1345..16cf48d3 100644 --- a/docs/reference/configuration/data-sources/btrfs.md +++ b/docs/reference/configuration/data-sources/btrfs.md @@ -76,6 +76,14 @@ next, the [Borg file cache](https://borgbackup.readthedocs.io/en/stable/internals/data-structures.html#cache) will never get cache hits on snapshotted files. This makes backing up Btrfs snapshots a little slower than non-snapshotted files that have consistent paths. +**It is also not possible to mitigate cache misses**, as the Btrfs hook uses +snapshot paths which change between borgmatic invocations, and the snapshots +are located outside the [runtime +directory](https://torsion.org/borgmatic/reference/configuration/runtime-directory/), +contrary to +[ZFS](https://torsion.org/borgmatic/reference/configuration/data-sources/zfs/#performance) +and +[LVM](https://torsion.org/borgmatic/reference/configuration/data-sources/lvm/#performance). With Borg version 2.x Even snapshotted files should get cache hits, because Borg 2.x is smarter about how