Re: [Qemu-devel] [PATCH RFC v3 00/27] COarse-grain LOck-stepping(COLO) Virtual Machines for Non-stop Service

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* zhanghailiang (zhang.zhanghailiang@huawei.com) wrote:
> This is the 3th version of COLO, it is only COLO frame part, include: VM checkpoint,
> failover, proxy API, block replication API, not include block replication.
> The block part has been sent by wencongyang:
> '[RFC PATCH 00/14] Block replication for continuous checkpoints'
> 
> You can get the integrated qemu colo patches from github:
> https://github.com/coloft/qemu/commits/colo-v1.0
> 
> Compared with the previous version, we have realized all parts of COLO frame, 
> and it is works now.
> 
> The main change since last version is, we use colo proxy mode instead of
> colo agent, they are all used for network packets compare, but proxy is more
> efficient, it is based on netfilter.
> Another modification is we implement new block replication scheme, 
> you can get more info from wencongyang's block patch series 
> 
> If you don't know about COLO, please refer to below link for detailed 
> information.
> 
> The idea is presented in Xen summit 2012, and 2013,
> and academia paper in SOCC 2013. It's also presented in KVM forum in 2013:
> http://www.linux-kvm.org/wiki/images/1/1d/Kvm-forum-2013-COLO.pdf
> 
> Previous posted RFC proposal:
> http://lists.nongnu.org/archive/html/qemu-devel/2014-06/msg05567.html
> http://lists.nongnu.org/archive/html/qemu-devel/2014-09/msg04459.html
> 
> The below is the detail about test COLO, you can also get this info
> from http://wiki.qemu.org/Features/COLO.
> * Hardware requirements
> There is at least one directly connected nic to forward the network requests
> from client to secondary VM. The directly connected nic must not be used by
> any other purpose.
> 
> * Network link topology
> =================================normal ======================================
>                                 +--------+
>                                 |client  |
>    master                       +----+---+                    slave
> -------------------------+           |            + -------------------------+
>    PVM                   |           +            |                          |
> +-------+         +----[eth0]-----[switch]-----[eth0]---------+              |
> |guest  |     +---+-+    |                        |       +---+-+            |
> |     [tap0]--+ br0 |    |                        |       | br0 |            |
> |       |     +-----+  [eth1]-----[forward]----[eth1]--+  +-----+      SVM   |
> +-------+                |                        |    |            +-------+|
>                          |                        |    |  +-----+   | guest ||
>                        [eth2]---[checkpoint]---[eth2]  +--+br1  |-[tap0]    ||
>                          |                        |       +-----+   |       ||
>                          |                        |                 +-------+|
> -------------------------+                        +--------------------------+
> e.g.
> master:
> br0: 192.168.0.33
> eth1: 192.168.1.33
> eth2: 192.168.2.33
> 
> slave:
> br0: 192.168.0.88
> br1: no ip address
> eth1: 192.168.1.88
> eth2: 192.168.2.88
> (Actually, you can also use eth0 as checkpoint channel)
> Note: in normal, SVM will always be linked to br1 like above until
> failover.
> 
> * Test environment prepare:
> 1. Set Up the Bridge and network environment
> You must setup you network environment like above picture,
> In master, setup a bridge br0, using command brctl, like:
> # ifconfig eth0 down
> # ifconfig eth0 0.0.0.0
> # brctl addbr br0
> # brctl addif br0 eth0
> # ifconfig br0 192.168.0.33 netmask 255.255.255.0
> # ifconfig eth0 up
> In slave, setup two bridge br0, br1, commands are same with above,
> please note that br1 is linked to eth1(the forward nic).
>
> 2.Qemu-ifup
> We need a script to bring up the TAP interface.
> You can find this info from http://en.wikibooks.org/wiki/QEMU/Networking.
> Master:
> root@master# cat /etc/qemu-ifup
> #!/bin/sh
> switch=br0
> if [ -n "$1" ]; then
>         ip link set $1 up
>         brctl addif ${switch} $1
> fi
> Slave:
> root@slave # cat /etc/qemu-ifup
> #!/bin/sh
> switch=br1  #in primary, switch is br0. in secondary switch is br1
> if [ -n "$1" ]; then
>         ip link set $1 up
>         brctl addif ${switch} $1
> fi 
> 
> 3. Prepare host kernel
> colo-proxy kernel module need cooperate with linux kernel.
> You should put a kernel patch 'colo-patch-for-kernel.patch'
> (It's based on linux kernel-3.19) which you can get from 
> https://github.com/gao-feng/colo-proxy.git
> and then compile kernel and intall the new kernel.
> 
> 4. Proxy module
> proxy module is used for network packets compare, you can also get the lastest
> version from: https://github.com/gao-feng/colo-proxy.git.
> You can compile and install it by using command 'make' && 'make install'.
> 
> 5. Modified iptables
> We have add a new rule to iptables command, so please get the patch from
> https://github.com/gao-feng/colo-proxy/blob/master/COLO-library_for_iptables-1.4.21.patch
> It is based on version 1.4.21.

I'm getting closer but I don't think I'm getting packets from the secondary
to the primary yet; it looks like the primary is holding onto it's packets
until the end of the 10second checkpoint.
Still debugging that but I'd take any tips.

> 2. startup qemu
> master:
> # qemu-system-x86_64 -enable-kvm -netdev tap,id=hn0,colo_script=./scripts/colo-proxy-script.sh,colo_nicname=eth1 -device virtio-net-pci,id=net-pci0,netdev=hn0 -boot c -drive driver=quorum,read-pattern=first,children.0.file.filename=suse11_3.img,children.0.driver=raw,children.1.file.driver=nbd+colo,children.1.file.host=192.168.2.88,children.1.file.port=8889,children.1.file.export=colo1,children.1.driver=raw,if=virtio -vnc :7 -m 2048 -smp 2 -device piix3-usb-uhci -device usb-tablet -monitor stdio -S
> slave:
> # qemu-system-x86_64 -enable-kvm -netdev tap,id=hn0,colo_script=./scripts/colo-proxy-script.sh,colo_nicname=eth1 -device virtio-net-pci,id=net-pci0,netdev=hn0 -boot c -drive driver=blkcolo,export=colo1,backing.file.filename=suse11_3.img,backing.driver=raw,if=virtio -vnc :7 -m 2048 -smp 2 -device piix3-usb-uhci -device usb-tablet -monitor stdio -incoming tcp:0:8888
> 
> 3. On Secondary VM's QEMU monitor, run
> (qemu) nbd_server_start 192.168.2.88:8889 
> 
> 4.on Primary VM's QEMU monitor, run following command:
> (qemu) migrate_set_capability colo on
> (qemu) migrate tcp:192.168.2.88:8888
> 
> 5. done
> You will see two runing VMs, whenever you make changes to PVM, SVM
> will be synced to PVM's state.
> 
> 6. failover test:
> You can kill SVM (PVM) and run 'colo_lost_heartbeat' in PVM's (SVM's) monitor
> at the same time, then PVM (SVM) will failover and client will not feel this
> change.

I've not got that to work yet; so far if I kill the PVM the SVM quits
shortly after.  (I've tried both 'q' in the PVMs monitor and also kill -9).

Dave

> It is still a framework, far away from commercial use,
> so any comments/feedbacks are warmly welcomed ;)
> 
> PS: 
> We (huawei) have cooperated with fujitsu on COLO work,
> and we work mainly on COLO frame and fujitsu will focus on COLO block.
> 
> TODO list:
> 1) Optimize the process of checkpoint, shorten the time-consuming
> 2) Add more debug/stat info 
> 3) Strengthen failover 
> 4) The capability of continuous FT
> 
> v3:
> - use proxy instead of colo agent to compare network packets
> - add block replication
> - Optimize failover disposal
> - handle shutdown
> 
> v2:
> - use QEMUSizedBuffer/QEMUFile as COLO buffer
> - colo support is enabled by default
> - add nic replication support
> - addressed comments from Eric Blake and Dr. David Alan Gilbert
> 
> v1:
> - implement the frame of colo
> 
> 
> zhanghailiang (27):
>   configure: Add parameter for configure to enable/disable COLO support
>   migration: Introduce capability 'colo' to migration
>   COLO: migrate colo related info to slave
>   migration: Integrate COLO checkpoint process into migration
>   migration: Integrate COLO checkpoint process into loadvm
>   migration: Don't send vm description in COLO mode
>   COLO: Implement colo checkpoint protocol
>   COLO: Add a new RunState RUN_STATE_COLO
>   QEMUSizedBuffer: Introduce two help functions for qsb
>   COLO: Save VM state to slave when do checkpoint
>   COLO RAM: Load PVM's dirty page into SVM's RAM cache temporarily
>   COLO VMstate: Load VM state into qsb before restore it
>   COLO RAM: Flush cached RAM into SVM's memory
>   COLO failover: Introduce a new command to trigger a failover
>   COLO failover: Implement COLO master/slave failover work
>   COLO failover: Don't do failover during loading VM's state
>   COLO: Add new command parameter 'colo_nicname' 'colo_script' for net
>   COLO NIC: Init/remove colo nic devices when add/cleanup tap devices
>   COLO NIC: Implement colo nic device interface configure()
>   COLO NIC : Implement colo nic init/destroy function
>   COLO NIC: Some init work related with proxy module
>   COLO: Do checkpoint according to the result of net packets comparing
>   COLO: Improve checkpoint efficiency by do additional periodic
>     checkpoint
>   COLO NIC: Implement NIC checkpoint and failover
>   COLO: Disable qdev hotplug when VM is in COLO mode
>   COLO: Implement shutdown checkpoint
>   COLO: Add block replication into colo process
> 
>  arch_init.c                            | 196 ++++++++-
>  configure                              |  14 +
>  hmp-commands.hx                        |  15 +
>  hmp.c                                  |   7 +
>  hmp.h                                  |   1 +
>  include/exec/cpu-all.h                 |   1 +
>  include/migration/migration-colo.h     |  57 +++
>  include/migration/migration-failover.h |  22 +
>  include/migration/migration.h          |  14 +
>  include/migration/qemu-file.h          |   3 +-
>  include/net/colo-nic.h                 |  25 ++
>  include/net/net.h                      |   4 +
>  include/sysemu/sysemu.h                |   3 +
>  migration/Makefile.objs                |   2 +
>  migration/colo-comm.c                  |  81 ++++
>  migration/colo-failover.c              |  48 +++
>  migration/colo.c                       | 743 +++++++++++++++++++++++++++++++++
>  migration/migration.c                  |  74 +++-
>  migration/qemu-file-buf.c              |  57 +++
>  net/Makefile.objs                      |   1 +
>  net/colo-nic.c                         | 438 +++++++++++++++++++
>  net/tap.c                              |  45 +-
>  qapi-schema.json                       |  27 +-
>  qemu-options.hx                        |  10 +-
>  qmp-commands.hx                        |  19 +
>  savevm.c                               |  10 +-
>  scripts/colo-proxy-script.sh           |  88 ++++
>  stubs/Makefile.objs                    |   1 +
>  stubs/migration-colo.c                 |  49 +++
>  vl.c                                   |  36 +-
>  30 files changed, 2047 insertions(+), 44 deletions(-)
>  create mode 100644 include/migration/migration-colo.h
>  create mode 100644 include/migration/migration-failover.h
>  create mode 100644 include/net/colo-nic.h
>  create mode 100644 migration/colo-comm.c
>  create mode 100644 migration/colo-failover.c
>  create mode 100644 migration/colo.c
>  create mode 100644 net/colo-nic.c
>  create mode 100755 scripts/colo-proxy-script.sh
>  create mode 100644 stubs/migration-colo.c
> 
> -- 
> 1.7.12.4
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK