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[Qemu-devel] [PATCH v10 10/16] docs: Document how to stream to an interm
From: |
Alberto Garcia |
Subject: |
[Qemu-devel] [PATCH v10 10/16] docs: Document how to stream to an intermediate layer |
Date: |
Thu, 6 Oct 2016 16:02:53 +0300 |
Signed-off-by: Alberto Garcia <address@hidden>
---
docs/live-block-ops.txt | 31 ++++++++++++++++++++-----------
1 file changed, 20 insertions(+), 11 deletions(-)
diff --git a/docs/live-block-ops.txt b/docs/live-block-ops.txt
index a257087..014c8c9 100644
--- a/docs/live-block-ops.txt
+++ b/docs/live-block-ops.txt
@@ -10,9 +10,9 @@ Snapshot live merge
Given a snapshot chain, described in this document in the following
format:
-[A] -> [B] -> [C] -> [D]
+[A] <- [B] <- [C] <- [D] <- [E]
-Where the rightmost object ([D] in the example) described is the current
+Where the rightmost object ([E] in the example) described is the current
image which the guest OS has write access to. To the left of it is its base
image, and so on accordingly until the leftmost image, which has no
base.
@@ -21,11 +21,14 @@ The snapshot live merge operation transforms such a chain
into a
smaller one with fewer elements, such as this transformation relative
to the first example:
-[A] -> [D]
+[A] <- [E]
-Currently only forward merge with target being the active image is
-supported, that is, data copy is performed in the right direction with
-destination being the rightmost image.
+Data is copied in the right direction with destination being the
+rightmost image, but any other intermediate image can be specified
+instead. In this example data is copied from [C] into [D], so [D] can
+be backed by [B]:
+
+[A] <- [B] <- [D] <- [E]
The operation is implemented in QEMU through image streaming facilities.
@@ -35,14 +38,20 @@ streaming operation completes it raises a QMP event.
'block_stream'
copies data from the backing file(s) into the active image. When finished,
it adjusts the backing file pointer.
-The 'base' parameter specifies an image which data need not be streamed from.
-This image will be used as the backing file for the active image when the
-operation is finished.
+The 'base' parameter specifies an image which data need not be
+streamed from. This image will be used as the backing file for the
+destination image when the operation is finished.
-In the example above, the command would be:
+In the first example above, the command would be:
-(qemu) block_stream virtio0 A
+(qemu) block_stream virtio0 file-A.img
+In order to specify a destination image different from the active
+(rightmost) one we can use its node name instead.
+
+In the second example above, the command would be:
+
+(qemu) block_stream node-D file-B.img
Live block copy
===============
--
2.9.3
- Re: [Qemu-devel] [PATCH v10 05/16] block: Check blockers in all nodes involved in a block-commit job, (continued)
- [Qemu-devel] [PATCH v10 04/16] block: Use block_job_add_bdrv() in backup_start(), Alberto Garcia, 2016/10/06
- [Qemu-devel] [PATCH v10 16/16] qemu-iotests: Test streaming to a Quorum child, Alberto Garcia, 2016/10/06
- [Qemu-devel] [PATCH v10 10/16] docs: Document how to stream to an intermediate layer,
Alberto Garcia <=
- [Qemu-devel] [PATCH v10 15/16] qemu-iotests: Add iotests.supports_quorum(), Alberto Garcia, 2016/10/06
- [Qemu-devel] [PATCH v10 13/16] qemu-iotests: Test overlapping stream and commit operations, Alberto Garcia, 2016/10/06
- [Qemu-devel] [PATCH v10 12/16] qemu-iotests: Test block-stream operations in parallel, Alberto Garcia, 2016/10/06
- [Qemu-devel] [PATCH v10 14/16] qemu-iotests: Test block-stream and block-commit in parallel, Alberto Garcia, 2016/10/06
- [Qemu-devel] [PATCH v10 11/16] qemu-iotests: Test streaming to an intermediate layer, Alberto Garcia, 2016/10/06