qemu/docs/COLO-FT.txt

18 Both primary VM (PVM) and secondary VM (SVM) run in parallel. They receive the
27 The primary node running the PVM, and the secondary node running the SVM
33 primary node, and then forwarded to the secondary node, so that both the PVM
44   Primary Node                                                            Secondary Node
47 | Primary VM |  +-----------+-----------+       +-----------+------------+  |Secondary VM|
88 Runs on both the primary and secondary nodes, to periodically check platform
89 availability. When the primary node suffers a hardware fail-stop failure,
94 When primary VM writes data into image, the colo disk manager captures this data
96 image is consistent with the context of primary VM 's image.
102 Primary side.
105 Delivers packets to Primary and Secondary, and then compare the responses from
150 127.0.0.1 is the Primary Host and 127.0.0.2 is the Secondary Host.
153 1. Primary:
154 Note: Initially, $imagefolder/primary.qcow2 needs to be copied to all hosts.
159 # imagefolder="/mnt/vms/colo-test-primary"
162    -device piix3-usb-uhci -device usb-tablet -name primary \
178 children.0.file.filename=$imagefolder/primary.qcow2,children.0.driver=qcow2 -S
182 size should be the same as primary.qcow2. Again, you don't need to change
201    -drive if=none,id=parent0,file.filename=$imagefolder/primary.qcow2,driver=qcow2 \
219      before running the qmp command migrate on primary QEMU
225 4. On Primary VM's QEMU monitor, issue command:
227 …arguments": {"command-line": "drive_add -n buddy driver=replication,mode=primary,file.driver=nbd,f…
233   a. There should be only one NBD Client for each primary disk.
244 If you killed the Secondary, then follow "Primary Failover". After that,
245 if you want to resume the replication, follow "Primary resume replication"
247 If you killed the Primary, then follow "Secondary Failover". After that,
250 == Primary Failover ==
251 The Secondary died, resume on the Primary
263 The Primary died, resume on the Secondary and prepare to become the new Primary
280 == Primary resume replication ==
283 Start the new Secondary (Steps 2 and 3 above), then on the Primary:
290 …arguments":{ "command-line": "drive_add -n buddy driver=replication,mode=primary,file.driver=nbd,f…
303 If this Primary previously was a Secondary, then we need to insert the
308 Become Primary and resume replication after new Secondary is up. Note
309 that now 127.0.0.1 is the Secondary and 127.0.0.2 is the Primary.
319 …arguments":{ "command-line": "drive_add -n buddy driver=replication,mode=primary,file.driver=nbd,f…