[PATCH 1/6] kbase: incrementalbackupinternals: Add snapshot terminology

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Make it obvious what's meant by 'overlay' and 'backing image' for sake
of extension of the document.

Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx>
---
 docs/kbase/incrementalbackupinternals.rst | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/docs/kbase/incrementalbackupinternals.rst b/docs/kbase/incrementalbackupinternals.rst
index 0c4b4f7486..eada0d2935 100644
--- a/docs/kbase/incrementalbackupinternals.rst
+++ b/docs/kbase/incrementalbackupinternals.rst
@@ -94,6 +94,21 @@ so, even if we obviously can't guarantee that.
 Integration with external snapshots
 ===================================

+External snapshot terminology
+-----------------------------
+
+External snapshots on a disk level consist of layered chains of disk images. An
+image in the chain can have a ``backing image`` placed below. Any chunk in the
+current image which was not written explicitly is transparent and if read the
+data from the backing image is passed through. An image placed on top of the
+current image is called ``overlay``.
+
+The bottommost backing image at the end of the chain is also usually described
+as ``base image``.
+
+The topmost overlay is the image which is being written to by the VM and is also
+described as the ``active`` layer or image.
+
 Handling of bitmaps
 -------------------

-- 
2.26.2




[Index of Archives]     [Virt Tools]     [Libvirt Users]     [Lib OS Info]     [Fedora Users]     [Fedora Desktop]     [Fedora SELinux]     [Big List of Linux Books]     [Yosemite News]     [KDE Users]     [Fedora Tools]

  Powered by Linux