diff options
| author | Tony Luck <tony.luck@intel.com> | 2005-11-07 09:05:22 -0800 |
|---|---|---|
| committer | Tony Luck <tony.luck@intel.com> | 2005-11-07 09:05:22 -0800 |
| commit | 0ad3a96f8ad910ecf87a25ec69ed360b284dee2e (patch) | |
| tree | 12d292fd58fc0f7a3eb56c89dfc23569f3ab6c00 /Documentation/device-mapper/snapshot.txt | |
| parent | f79b348856fbaf77e4a0c5cb08a808e5879967a9 (diff) | |
| parent | 5b2f7ffcb734d3046144dfbd5ac6d76254a9e522 (diff) | |
Auto-update from upstream
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 dca274ff400..a5009c8300f 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 |