Virtual machine (VM) replication is a well known technique for providing application-agnostic software-implemented hardware fault tolerance "non-stop service". COLO is a high availability solution. Both primary VM (PVM) and secondary VM (SVM) run in parallel. They receive the same request from client, and generate response in parallel too. If the response packets from PVM and SVM are identical, they are released immediately. Otherwise, a VM checkpoint (on demand) is conducted. The idea is presented in Xen summit 2012, and 2013, and academia paper in SOCC 2013. It's also presented in KVM forum 2013: http://www.linux-kvm.org/wiki/images/1/1d/Kvm-forum-2013-COLO.pdf Please refer to above document for detailed information. Please also refer to previous posted RFC proposal: http://lists.nongnu.org/archive/html/qemu-devel/2014-06/msg05567.html The patchset is also hosted on github: https://github.com/macrosheep/qemu/tree/colo_v0.1 This patchset is RFC, implements the frame of colo, without failover and nic/disk replication. But it is ready for demo the COLO idea above QEMU-Kvm. Steps using this patchset to get an overview of COLO: 1. configure the source with --enable-colo option 2. compile 3. just like QEMU's normal migration, run 2 QEMU VM: - Primary VM - Secondary VM with -incoming tcp:[IP]:[PORT] option 4. on Primary VM's QEMU monitor, run following command: migrate_set_capability colo on migrate tcp:[IP]:[PORT] 5. done you will see two runing VMs, whenever you make changes to PVM, SVM will be synced to PVM's state. TODO list: 1. failover 2. nic replication 3. disk replication[COLO Disk manager] Any comments/feedbacks are warmly welcomed. Thanks, Yang Yang Hongyang (17): configure: add CONFIG_COLO to switch COLO support COLO: introduce an api colo_supported() to indicate COLO support COLO migration: add a migration capability 'colo' COLO info: use colo info to tell migration target colo is enabled COLO save: integrate COLO checkpointed save into qemu migration COLO restore: integrate COLO checkpointed restore into qemu restore COLO buffer: implement colo buffer as well as QEMUFileOps based on it COLO: disable qdev hotplug COLO ctl: implement API's that communicate with colo agent COLO ctl: introduce is_slave() and is_master() COLO ctl: implement colo checkpoint protocol COLO ctl: add a RunState RUN_STATE_COLO COLO ctl: implement colo save COLO ctl: implement colo restore COLO save: reuse migration bitmap under colo checkpoint COLO ram cache: implement colo ram cache on slaver HACK: trigger checkpoint every 500ms Makefile.objs | 2 + arch_init.c | 174 +++++++++- configure | 14 + include/exec/cpu-all.h | 1 + include/migration/migration-colo.h | 36 +++ include/migration/migration.h | 13 + include/qapi/qmp/qerror.h | 3 + migration-colo-comm.c | 78 +++++ migration-colo.c | 643 +++++++++++++++++++++++++++++++++++++ migration.c | 45 ++- qapi-schema.json | 9 +- stubs/Makefile.objs | 1 + stubs/migration-colo.c | 34 ++ vl.c | 12 + 14 files changed, 1044 insertions(+), 21 deletions(-) create mode 100644 include/migration/migration-colo.h create mode 100644 migration-colo-comm.c create mode 100644 migration-colo.c create mode 100644 stubs/migration-colo.c -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
