[PATCH] Fix dm-snapshot tutorial in Documentation
I've recently added this documentation, Alasdair gave some corrections, and
here are some further corrections on top of his work (partly style issue,
partly a technical error due to different past experience, partly a note
which I've added - i.e. transient snapshots are lighter).
Cc: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/Documentation/device-mapper/snapshot.txt b/Documentation/device-mapper/snapshot.txt
index dca274f..a5009c8 100644
--- a/Documentation/device-mapper/snapshot.txt
+++ b/Documentation/device-mapper/snapshot.txt
@@ -19,7 +19,6 @@
*) snapshot-origin <origin>
which will normally have one or more snapshots based on it.
-You must create the snapshot-origin device before you can create snapshots.
Reads will be mapped directly to the backing device. For each write, the
original data will be saved in the <COW device> of each snapshot to keep
its visible content unchanged, at least until the <COW device> fills up.
@@ -27,7 +26,7 @@
*) snapshot <origin> <COW device> <persistent?> <chunksize>
-A snapshot is created of the <origin> block device. Changed chunks of
+A snapshot of the <origin> block device is created. Changed chunks of
<chunksize> sectors will be stored on the <COW device>. Writes will
only go to the <COW device>. Reads will come from the <COW device> or
from <origin> for unchanged data. <COW device> will often be
@@ -37,6 +36,8 @@
<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.
How this is used by LVM2