dm vdo: document minimum metadata size requirements Signed-off-by: Matthew Sakai <msakai@redhat.com> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
diff --git a/Documentation/admin-guide/device-mapper/vdo.rst b/Documentation/admin-guide/device-mapper/vdo.rst index a357258..7e1ecaf 100644 --- a/Documentation/admin-guide/device-mapper/vdo.rst +++ b/Documentation/admin-guide/device-mapper/vdo.rst
@@ -34,6 +34,17 @@ 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 ================