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| author | Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> | 2005-11-07 01:01:01 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-11-07 07:53:54 -0800 |
| commit | 411f11405c99141233970c98d23d6a5ec88a4f7f (patch) | |
| tree | afad7a5170c5a68a66fca4277fcbd2b20a0a2cc2 /Documentation/device-mapper/snapshot.txt | |
| parent | f73195ad7e68fb4e546350222d31e19ebc1d3578 (diff) | |
| download | op-kernel-dev-411f11405c99141233970c98d23d6a5ec88a4f7f.zip op-kernel-dev-411f11405c99141233970c98d23d6a5ec88a4f7f.tar.gz | |
[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>
Diffstat (limited to 'Documentation/device-mapper/snapshot.txt')
| -rw-r--r-- | Documentation/device-mapper/snapshot.txt | 5 |
1 files changed, 3 insertions, 2 deletions
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 @@ There are two dm targets available: snapshot and snapshot-origin. *) 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 @@ its visible content unchanged, at least until the <COW device> fills up. *) 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 @@ 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. How this is used by LVM2 |
