QMP部分功能支持事务性（事务的目的是当其中一件事失败后，会自动回滚，保证数据一致性，但这里也可用于保证创建bitmap和开始备份之间没有缺少数据），因此上述1️⃣通过事务操作
{ "execute": "transaction", "arguments": { "actions": [ {"type": "block-dirty-bitmap-add", "data": {"node": "drive-virtio-disk0", "name": "bitmap0"} }, {"type": "drive-backup", "data": {"device": "drive-virtio-disk0", "target": "/path/to/full_backup.img", "sync": "top"} } ] } }范例如下
virsh qemu-monitor-command DOMAIN --pretty '{ "execute": "transaction", "arguments": { "actions": [ { "type": "block-dirty-bitmap-add", "data": {"node":"drive-virtio-disk0", "name":"bitmap0"}}, { "type": "drive-backup", "data": {"device": "drive-virtio-disk0", "target": "/opt/backup/top.img","sync":"top" }} ]} }' # ...运行一段时间... virsh qemu-monitor-command DOMAIN --pretty '{ "execute" : "drive-backup" , "arguments" : { "device" : "drive-virtio-disk0" , "sync" : "incremental" , "bitmap" : "bitmap0" , "target" : "/opt/backup/inc.0.qcow2" } }' # ...又运行一段时间... virsh qemu-monitor-command DOMAIN --pretty '{ "execute" : "drive-backup" , "arguments" : { "device" : "drive-virtio-disk0" , "sync" : "incremental" , "bitmap" : "bitmap0" , "target" : "/opt/backup/inc.1.qcow2" } }'如果之前已经创建过bitmap，此刻想忽略bitmap，重新做一次完整备份，并重置bitmap（用于接下来的增量备份），则可以
{ "execute": "transaction", "arguments": { "actions": [ {"type": "block-dirty-bitmap-clear", "data": {"node": "drive-virtio-disk0", "name": "bitmap0"} }, {"type": "drive-backup", "data": {"device": "drive-virtio-disk0", "target": "/path/to/new_full_backup.img", "sync": "top"} } ] } } 13. 远程备份经测试，qemu仅支持一种远程备份方法：iscsi，方法就是在drive-backup的target里使用iscsi的格式即可：
# target内容 格式 iscsi://[<username>[%<password>]@]<host>[:<port>]/<target-iqn-name>/<lun> 例子 iscsi://192.168.1.100:3260/iqn.2019-01.com.iaas/0 virsh qemu-monitor-command DOMAIN '{ "execute" : "drive-backup" , "arguments" : { "device" : "drive-virtio-disk0" , "sync" : "incremental" , "bitmap" : "bitmap0" , "target" : "iscsi://192.168.1.100:3260/iqn.2019-01.com.iaas/0" } }' 14. 备份任务管理如果迟迟没有收到事件，要如何查看备份任务是否还在进行中呢，或者想中断备份，又如何操作呢
查看备份任务
# 通过qmp查看 virsh qemu-monitor-command DOMAIN --pretty '{ "execute": "query-block-jobs" }' # 通过hmp查看 virsh qemu-monitor-command DOMAIN --hmp 'info block-jobs'输出
# 通过qmp查看，有任务时候的输出 { "return": [ { "auto-finalize": true, "io-status": "ok", "device": "drive-virtio-disk1", "auto-dismiss": true, "busy": true, "len": 1073741824, "offset": 2424832, "status": "running", "paused": false, "speed": 0, "ready": false, "type": "backup" }, { "auto-finalize": true, "io-status": "ok", "device": "drive-virtio-disk0", "auto-dismiss": true, "busy": true, "len": 21474836480, "offset": 163840000, "status": "running", "paused": false, "speed": 0, "ready": false, "type": "backup" } ], "id": "libvirt-45" } # 通过qmp查看，无任务时候的输出 { "return": [ ], "id": "libvirt-360" } # 通过hmp查看，有任务时候的输出 Type backup, device drive-virtio-disk1: Completed 20185088 of 1073741824 bytes, speed limit 0 bytes/s Type backup, device drive-virtio-disk0: Completed 181403648 of 21474836480 bytes, speed limit 0 bytes/s # 通过hmp查看，无任务时候的输出 No active jobs停止备份任务
virsh qemu-monitor-command DOMAIN --pretty '{ "execute": "block-job-cancel", "arguments": { "device": "drive-virtio-disk1", "force": true } }'如果不带force参数，则默认为false，在false情况下当任务处于暂停状态时无法停止
输出
{"return":{},"id":"libvirt-5880"}同时收到事件
2019-02-03 13:02:58.535+0000: event JOB_STATUS_CHANGE for domain DOMAIN: {"status":"aborting","id":"drive-virtio-disk1"} 2019-02-03 13:02:58.541+0000: event BLOCK_JOB_CANCELLED for domain DOMAIN: {"device":"drive-virtio-disk1","len":2147483648,"offset":29687808,"speed":0,"type":"backup"} 2019-02-03 13:02:58.541+0000: event JOB_STATUS_CHANGE for domain DOMAIN: {"status":"concluded","id":"drive-virtio-disk1"} 2019-02-03 13:02:58.541+0000: event JOB_STATUS_CHANGE for domain DOMAIN: {"status":"null","id":"drive-virtio-disk1"}▷ 根据官方文档，JOB_STATUS_CHANGE事件是从qemu-3.0才出现的，但在qemu-2.12时就能看到了（2.9看不到），尚未深究
▷ 因此，若qemu是2.12，当收到JOB_STATUS_CHANGE事件，应当不予理会，后面不再赘述
暂停备份任务
virsh qemu-monitor-command DOMAIN '{ "execute" : "block-job-pause", "arguments" : { "device" : "drive-virtio-disk0" } }'输出
{"return":{},"id":"libvirt-5882"}同时收到事件（假设之前任务处于running状态）
2019-01-22 02:42:55.503+0000: event JOB_STATUS_CHANGE for domain DOMAIN: {"status":"paused","id":"drive-virtio-disk0"}恢复已暂停的备份任务
virsh qemu-monitor-command DOMAIN '{ "execute" : "block-job-resume", "arguments" : { "device" : "drive-virtio-disk0" } }'输出
{"return":{},"id":"libvirt-5999"}同时收到事件
2019-01-22 02:46:04.928+0000: event JOB_STATUS_CHANGE for domain DOMAIN: {"status":"running","id":"drive-virtio-disk0"} 15. 事件查看监听事件