From cb824724dccb3195d22cad96e7b65fe13621d0a6 Mon Sep 17 00:00:00 2001 From: Matthew Sakai Date: Thu, 7 Mar 2024 16:02:35 -0500 Subject: dm vdo: document minimum metadata size requirements Signed-off-by: Matthew Sakai Signed-off-by: Mike Snitzer --- Documentation/admin-guide/device-mapper/vdo.rst | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/Documentation/admin-guide/device-mapper/vdo.rst b/Documentation/admin-guide/device-mapper/vdo.rst index a3572582ead8..7e1ecafdf91e 100644 --- a/Documentation/admin-guide/device-mapper/vdo.rst +++ b/Documentation/admin-guide/device-mapper/vdo.rst @@ -34,6 +34,17 @@ The repo also contains additional userspace tools which can be used to inspect a vdo target's on-disk metadata. Fortunately, these tools are rarely needed except by dm-vdo developers. +Metadata requirements +===================== + +Each vdo volume reserves 3GB of space for metadata, or more depending on +its configuration. It is helpful to check that the space saved by +deduplication and compression is not cancelled out by the metadata +requirements. An estimation of the space saved for a specific dataset can +be computed with the vdo estimator tool, which is available at: + +https://github.com/dm-vdo/vdoestimator/ + Target interface ================ -- cgit v1.2.3