[Qemu-block] [PATCH RFC 1/7] docs/block-replication: Add description for shared-disk case
Introuduce the scenario of shared-disk block replication and how to use it. Signed-off-by: zhanghailiang Signed-off-by: Wen Congyang Signed-off-by: Zhang Chen --- docs/block-replication.txt | 131 +++-- 1 file changed, 127 insertions(+), 4 deletions(-) diff --git a/docs/block-replication.txt b/docs/block-replication.txt index 6bde673..97fcfc1 100644 --- a/docs/block-replication.txt +++ b/docs/block-replication.txt @@ -24,7 +24,7 @@ only dropped at next checkpoint time. To reduce the network transportation effort during a vmstate checkpoint, the disk modification operations of the Primary disk are asynchronously forwarded to the Secondary node. -== Workflow == +== Non-shared disk workflow == The following is the image of block replication workflow: +--+++ @@ -57,7 +57,7 @@ The following is the image of block replication workflow: 4) Secondary write requests will be buffered in the Disk buffer and it will overwrite the existing sector content in the buffer. -== Architecture == +== None-shared disk architecture == We are going to implement block replication from many basic blocks that are already in QEMU. @@ -106,6 +106,74 @@ any state that would otherwise be lost by the speculative write-through of the NBD server into the secondary disk. So before block replication, the primary disk and secondary disk should contain the same data. +== Shared Disk Mode Workflow == +The following is the image of block replication workflow: + ++--+++ +|Primary Write Requests||Secondary Write Requests| ++--+++ + | | + | (4) + | V + | /-\ + | (2)Forward and write through | | + | +--> | Disk Buffer | + | || | + | |\-/ + | |(1)read | + | | | + (3)write | | | backing file + V | | + +-+ | + | Shared Disk | <-+ + +-+ + +1) Primary writes will read original data and forward it to Secondary + QEMU. +2) Before Primary write requests are written to Shared disk, the + original sector content will be read from Shared disk and + forwarded and buffered in the Disk buffer on the secondary site, + but it will not overwrite the existing + sector content(it could be from either "Secondary Write Requests" or + previous COW of "Primary Write Requests") in the Disk buffer. +3) Primary write requests will be written to Shared disk. +4) Secondary write requests will be buffered in the Disk buffer and it + will overwrite the existing sector content in the buffer. + +== Shared Disk Mode Architecture == +We are going to implement block replication from many basic +blocks that are already in QEMU. + virtio-blk || .-- + / || | Secondary +/ || '-- + /|| virtio-blk + / || | + | || replication(5) + |NBD > NBD (2) | + | client ||server ---> hidden disk <-- active disk(4) + | ^ || | + | replication(1) || | + | | || | + | +-' || | + (3) |drive-backup sync=none || | +. | +-+ || | +Primary | | | || backing| +' | | || | + V | | + +---+| + | shared disk | <--+ +
Re: [Qemu-block] [PATCH RFC 1/7] docs/block-replication: Add description for shared-disk case
On 10/20/2016 09:57 PM, zhanghailiang wrote:
Introuduce the scenario of shared-disk block replication
and how to use it.
Signed-off-by: zhanghailiang
Signed-off-by: Wen Congyang
Signed-off-by: Zhang Chen
---
docs/block-replication.txt | 131 +++--
1 file changed, 127 insertions(+), 4 deletions(-)
diff --git a/docs/block-replication.txt b/docs/block-replication.txt
index 6bde673..97fcfc1 100644
--- a/docs/block-replication.txt
+++ b/docs/block-replication.txt
@@ -24,7 +24,7 @@ only dropped at next checkpoint time. To reduce the network
transportation
effort during a vmstate checkpoint, the disk modification operations of
the Primary disk are asynchronously forwarded to the Secondary node.
-== Workflow ==
+== Non-shared disk workflow ==
The following is the image of block replication workflow:
+--+++
@@ -57,7 +57,7 @@ The following is the image of block replication workflow:
4) Secondary write requests will be buffered in the Disk buffer and it
will overwrite the existing sector content in the buffer.
-== Architecture ==
+== None-shared disk architecture ==
s/None-shared/Non-shared/g
We are going to implement block replication from many basic
blocks that are already in QEMU.
@@ -106,6 +106,74 @@ any state that would otherwise be lost by the speculative
write-through
of the NBD server into the secondary disk. So before block replication,
the primary disk and secondary disk should contain the same data.
+== Shared Disk Mode Workflow ==
+The following is the image of block replication workflow:
+
++--+++
+|Primary Write Requests||Secondary Write Requests|
++--+++
+ | |
+ | (4)
+ | V
+ | /-\
+ | (2)Forward and write through | |
+ | +--> | Disk Buffer |
+ | || |
+ | |\-/
+ | |(1)read |
+ | | |
+ (3)write | | | backing file
+ V | |
+ +-+ |
+ | Shared Disk | <-+
+ +-+
+
+1) Primary writes will read original data and forward it to Secondary
+ QEMU.
+2) Before Primary write requests are written to Shared disk, the
+ original sector content will be read from Shared disk and
+ forwarded and buffered in the Disk buffer on the secondary site,
+ but it will not overwrite the existing
extra spaces at the end of line
+ sector content(it could be from either "Secondary Write Requests" or
Need a space before "(" for better style.
+ previous COW of "Primary Write Requests") in the Disk buffer.
+3) Primary write requests will be written to Shared disk.
+4) Secondary write requests will be buffered in the Disk buffer and it
+ will overwrite the existing sector content in the buffer.
+
+== Shared Disk Mode Architecture ==
+We are going to implement block replication from many basic
+blocks that are already in QEMU.
+ virtio-blk ||
.--
+ / || |
Secondary
+/ ||
'--
+ /||
virtio-blk
+ / ||
|
+ | ||
replication(5)
+ |NBD > NBD (2)
|
+ | client ||server ---> hidden disk <--
active disk(4)
+ | ^ || |
+ | replication(1) || |
+ | | || |
+ | +-' || |
+ (3) |drive-backup sync=none || |
+. | +-+ || |
+Primary | | | || backing|
+' | | || |
+ V |
Re: [Qemu-block] [PATCH RFC 1/7] docs/block-replication: Add description for shared-disk case
On 2016/10/25 17:03, Changlong Xie wrote:
On 10/20/2016 09:57 PM, zhanghailiang wrote:
Introuduce the scenario of shared-disk block replication
and how to use it.
Signed-off-by: zhanghailiang
Signed-off-by: Wen Congyang
Signed-off-by: Zhang Chen
---
docs/block-replication.txt | 131
+++--
1 file changed, 127 insertions(+), 4 deletions(-)
diff --git a/docs/block-replication.txt b/docs/block-replication.txt
index 6bde673..97fcfc1 100644
--- a/docs/block-replication.txt
+++ b/docs/block-replication.txt
@@ -24,7 +24,7 @@ only dropped at next checkpoint time. To reduce the network
transportation
effort during a vmstate checkpoint, the disk modification operations of
the Primary disk are asynchronously forwarded to the Secondary node.
-== Workflow ==
+== Non-shared disk workflow ==
The following is the image of block replication workflow:
+--+++
@@ -57,7 +57,7 @@ The following is the image of block replication workflow:
4) Secondary write requests will be buffered in the Disk buffer and it
will overwrite the existing sector content in the buffer.
-== Architecture ==
+== None-shared disk architecture ==
s/None-shared/Non-shared/g
We are going to implement block replication from many basic
blocks that are already in QEMU.
@@ -106,6 +106,74 @@ any state that would otherwise be lost by the speculative
write-through
of the NBD server into the secondary disk. So before block replication,
the primary disk and secondary disk should contain the same data.
+== Shared Disk Mode Workflow ==
+The following is the image of block replication workflow:
+
++--+++
+|Primary Write Requests||Secondary Write Requests|
++--+++
+ | |
+ | (4)
+ | V
+ | /-\
+ | (2)Forward and write through | |
+ | +--> | Disk Buffer |
+ | || |
+ | |\-/
+ | |(1)read |
+ | | |
+ (3)write | | | backing file
+ V | |
+ +-+ |
+ | Shared Disk | <-+
+ +-+
+
+1) Primary writes will read original data and forward it to Secondary
+ QEMU.
+2) Before Primary write requests are written to Shared disk, the
+ original sector content will be read from Shared disk and
+ forwarded and buffered in the Disk buffer on the secondary site,
+ but it will not overwrite the existing
extra spaces at the end of line
+ sector content(it could be from either "Secondary Write Requests" or
Need a space before "(" for better style.
+ previous COW of "Primary Write Requests") in the Disk buffer.
+3) Primary write requests will be written to Shared disk.
+4) Secondary write requests will be buffered in the Disk buffer and it
+ will overwrite the existing sector content in the buffer.
+
+== Shared Disk Mode Architecture ==
+We are going to implement block replication from many basic
+blocks that are already in QEMU.
+ virtio-blk ||
.--
+ / || |
Secondary
+/ ||
'--
+ /||
virtio-blk
+ / ||
|
+ | ||
replication(5)
+ |NBD > NBD (2)
|
+ | client ||server ---> hidden disk <--
active disk(4)
+ | ^ || |
+ | replication(1) || |
+ | | || |
+ | +-' || |
+ (3) |drive-backup sync=none || |
+. | +-+ || |
+Primary | | | || backing|
+' | |
Re: [Qemu-block] [PATCH RFC 1/7] docs/block-replication: Add description for shared-disk case
On 11/28/2016 01:13 PM, Hailiang Zhang wrote:
On 2016/10/25 17:03, Changlong Xie wrote:
On 10/20/2016 09:57 PM, zhanghailiang wrote:
Introuduce the scenario of shared-disk block replication
and how to use it.
Signed-off-by: zhanghailiang
Signed-off-by: Wen Congyang
Signed-off-by: Zhang Chen
---
docs/block-replication.txt | 131
+++--
1 file changed, 127 insertions(+), 4 deletions(-)
diff --git a/docs/block-replication.txt b/docs/block-replication.txt
index 6bde673..97fcfc1 100644
--- a/docs/block-replication.txt
+++ b/docs/block-replication.txt
@@ -24,7 +24,7 @@ only dropped at next checkpoint time. To reduce the
network transportation
effort during a vmstate checkpoint, the disk modification
operations of
the Primary disk are asynchronously forwarded to the Secondary node.
-== Workflow ==
+== Non-shared disk workflow ==
The following is the image of block replication workflow:
+--+
++
@@ -57,7 +57,7 @@ The following is the image of block replication
workflow:
4) Secondary write requests will be buffered in the Disk
buffer and it
will overwrite the existing sector content in the buffer.
-== Architecture ==
+== None-shared disk architecture ==
s/None-shared/Non-shared/g
We are going to implement block replication from many basic
blocks that are already in QEMU.
@@ -106,6 +106,74 @@ any state that would otherwise be lost by the
speculative write-through
of the NBD server into the secondary disk. So before block
replication,
the primary disk and secondary disk should contain the same data.
+== Shared Disk Mode Workflow ==
+The following is the image of block replication workflow:
+
++--+++
+|Primary Write Requests||Secondary Write Requests|
++--+++
+ | |
+ | (4)
+ | V
+ | /-\
+ | (2)Forward and write through | |
+ | +--> | Disk Buffer |
+ | || |
+ | |\-/
+ | |(1)read |
+ | | |
+ (3)write | | | backing file
+ V | |
+ +-+ |
+ | Shared Disk | <-+
+ +-+
+
+1) Primary writes will read original data and forward it to
Secondary
+ QEMU.
+2) Before Primary write requests are written to Shared disk, the
+ original sector content will be read from Shared disk and
+ forwarded and buffered in the Disk buffer on the secondary site,
+ but it will not overwrite the existing
extra spaces at the end of line
+ sector content(it could be from either "Secondary Write
Requests" or
Need a space before "(" for better style.
+ previous COW of "Primary Write Requests") in the Disk buffer.
+3) Primary write requests will be written to Shared disk.
+4) Secondary write requests will be buffered in the Disk buffer
and it
+ will overwrite the existing sector content in the buffer.
+
+== Shared Disk Mode Architecture ==
+We are going to implement block replication from many basic
+blocks that are already in QEMU.
+ virtio-blk
|| .--
+ /
|| | Secondary
+/
|| '--
+ /
|| virtio-blk
+ /
|| |
+ |
|| replication(5)
+ |NBD > NBD
(2) |
+ | client ||server ---> hidden
disk <-- active disk(4)
+ | ^ || |
+ | replication(1) || |
+ | | || |
+ | +-' || |
+ (3) |drive-backup sync=none || |
+. | +-+ || |
+Primary | | | || backing|
+' | | || |
+ V | |
+ +
Re: [Qemu-block] [PATCH RFC 1/7] docs/block-replication: Add description for shared-disk case
On 2016/11/28 14:00, Changlong Xie wrote:
On 11/28/2016 01:13 PM, Hailiang Zhang wrote:
On 2016/10/25 17:03, Changlong Xie wrote:
On 10/20/2016 09:57 PM, zhanghailiang wrote:
Introuduce the scenario of shared-disk block replication
and how to use it.
Signed-off-by: zhanghailiang
Signed-off-by: Wen Congyang
Signed-off-by: Zhang Chen
---
docs/block-replication.txt | 131
+++--
1 file changed, 127 insertions(+), 4 deletions(-)
diff --git a/docs/block-replication.txt b/docs/block-replication.txt
index 6bde673..97fcfc1 100644
--- a/docs/block-replication.txt
+++ b/docs/block-replication.txt
@@ -24,7 +24,7 @@ only dropped at next checkpoint time. To reduce the
network transportation
effort during a vmstate checkpoint, the disk modification
operations of
the Primary disk are asynchronously forwarded to the Secondary node.
-== Workflow ==
+== Non-shared disk workflow ==
The following is the image of block replication workflow:
+--+
++
@@ -57,7 +57,7 @@ The following is the image of block replication
workflow:
4) Secondary write requests will be buffered in the Disk
buffer and it
will overwrite the existing sector content in the buffer.
-== Architecture ==
+== None-shared disk architecture ==
s/None-shared/Non-shared/g
We are going to implement block replication from many basic
blocks that are already in QEMU.
@@ -106,6 +106,74 @@ any state that would otherwise be lost by the
speculative write-through
of the NBD server into the secondary disk. So before block
replication,
the primary disk and secondary disk should contain the same data.
+== Shared Disk Mode Workflow ==
+The following is the image of block replication workflow:
+
++--+++
+|Primary Write Requests||Secondary Write Requests|
++--+++
+ | |
+ | (4)
+ | V
+ | /-\
+ | (2)Forward and write through | |
+ | +--> | Disk Buffer |
+ | || |
+ | |\-/
+ | |(1)read |
+ | | |
+ (3)write | | | backing file
+ V | |
+ +-+ |
+ | Shared Disk | <-+
+ +-+
+
+1) Primary writes will read original data and forward it to
Secondary
+ QEMU.
+2) Before Primary write requests are written to Shared disk, the
+ original sector content will be read from Shared disk and
+ forwarded and buffered in the Disk buffer on the secondary site,
+ but it will not overwrite the existing
extra spaces at the end of line
+ sector content(it could be from either "Secondary Write
Requests" or
Need a space before "(" for better style.
+ previous COW of "Primary Write Requests") in the Disk buffer.
+3) Primary write requests will be written to Shared disk.
+4) Secondary write requests will be buffered in the Disk buffer
and it
+ will overwrite the existing sector content in the buffer.
+
+== Shared Disk Mode Architecture ==
+We are going to implement block replication from many basic
+blocks that are already in QEMU.
+ virtio-blk
|| .--
+ /
|| | Secondary
+/
|| '--
+ /
|| virtio-blk
+ /
|| |
+ |
|| replication(5)
+ |NBD > NBD
(2) |
+ | client ||server ---> hidden
disk <-- active disk(4)
+ | ^ || |
+ | replication(1) || |
+ | | || |
+ | +-' || |
+ (3) |drive-backup sync=none || |
+. | +-+ || |
+Primary | | | || backing|
+' | | || |
+ V |
