path: root/Documentation/device-mapper/snapshot.txt
diff options
Diffstat (limited to 'Documentation/device-mapper/snapshot.txt')
1 files changed, 7 insertions, 3 deletions
diff --git a/Documentation/device-mapper/snapshot.txt b/Documentation/device-mapper/snapshot.txt
index 0d5bc46dc167..ad6949bff2e3 100644
--- a/Documentation/device-mapper/snapshot.txt
+++ b/Documentation/device-mapper/snapshot.txt
@@ -41,9 +41,13 @@ useless and be disabled, returning errors. So it is important to monitor
the amount of free space and expand the <COW device> before it fills up.
<persistent?> is P (Persistent) or N (Not persistent - will not survive
-after reboot).
-The difference is that for transient snapshots less metadata must be
-saved on disk - they can be kept in memory by the kernel.
+after reboot). O (Overflow) can be added as a persistent store option
+to allow userspace to advertise its support for seeing "Overflow" in the
+snapshot status. So supported store types are "P", "PO" and "N".
+The difference between persistent and transient is with transient
+snapshots less metadata must be saved on disk - they can be kept in
+memory by the kernel.
* snapshot-merge <origin> <COW device> <persistent> <chunksize>