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user-level: 0.807
hypervisor: 0.759
KVM: 0.752
i386: 0.751
virtual: 0.740
x86: 0.733
TCG: 0.729
vnc: 0.727
permissions: 0.727
peripherals: 0.727
VMM: 0.721
register: 0.720
risc-v: 0.711
boot: 0.710
mistranslation: 0.705
performance: 0.705
ppc: 0.697
arm: 0.695
assembly: 0.691
network: 0.684
debug: 0.683
device: 0.679
architecture: 0.674
graphic: 0.667
socket: 0.663
kernel: 0.662
files: 0.657
semantic: 0.656
PID: 0.650
drive-backup with iscsi will cause vm disk no response
virsh qemu-monitor-command ${DOMAIN} '{ "execute" : "drive-backup" , "arguments" : { "device" : "drive-virtio-disk0" , "sync" : "top" , "target" : "iscsi://192.168.1.100:3260/iqn.2019-01.com.iaas/0" } }'
When the drive-backup is running, I manually crash the iscsi server（or interrupt network, eg. iptables -j DROP）.
Then after less than 1 minute：
virsh qemu-monitor-command ${DOMAIN} --pretty '{ "execute": "query-block" }' will block and no any response, until timeout. This is still excusable.
But, the disk（drive-virtio-disk0）will occur the same situation：in vm os, the disk will block and no any response.
In other words, when qemu and iscsi-server lose contact, It will cause the vm unable.
---
Host: centos 7.5
qemu version: ovirt-4.2（qemu-2.12.0）
qemu command line: qemu-system-x86_64 -name guest=test,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-190-test./master-key.aes -machine pc-i440fx-3.1,accel=kvm,usb=off,dump-guest-core=off,mem-merge=off -m 1024 -mem-prealloc -mem-path /dev/hugepages1G/libvirt/qemu/190-test -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid 1c8611c2-a18a-4b1c-b40b-9d82040eafa4 -smbios type=1,manufacturer=IaaS -no-user-config -nodefaults -chardev socket,id=charmonitor,fd=31,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot menu=on,strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x3 -drive file=/opt/vol/sas/fb0c7c37-13e7-41fe-b3f8-f0fbaaeec7ce,format=qcow2,if=none,id=drive-virtio-disk0,cache=writeback -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1,write-cache=on -drive file=/opt/vol/sas/bde66671-536d-49cd-8b46-a4f1ea7be513,format=qcow2,if=none,id=drive-virtio-disk1,cache=writeback -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x7,drive=drive-virtio-disk1,id=virtio-disk1,write-cache=on -netdev tap,fd=33,id=hostnet0,vhost=on,vhostfd=34 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:85:45:3e:d4:3a,bus=pci.0,addr=0x6 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev socket,id=charchannel0,fd=35,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0 -device usb-tablet,id=input0,bus=usb.0,port=1 -vnc 0.0.0.0:0,password -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 -msg timestamp=on
iscsi：
yum -y install targetcli python-rtslib
systemctl start target
systemctl enable target
targetcli /iscsi create iqn.2019-01.com.iaas
targetcli /iscsi/iqn.2019-01.com.iaas/tpg1 set attribute authentication=0 demo_mode_write_protect=0 generate_node_acls=1
targetcli /iscsi/iqn.2019-01.com.iaas/tpg1/portals create 192.168.1.100 3260
targetcli /backstores/fileio create testfile1 /backup/file1 2G
targetcli /iscsi/iqn.2019-01.com.iaas/tpg1/luns create /backstores/fileio/testfile1
On Fri, Feb 15, 2019 at 03:03:34AM -0000, Cheng Chen wrote:
> When the drive-backup is running, I manually crash the iscsi server（or
> interrupt network, eg. iptables -j DROP）.
>
> Then after less than 1 minute：
> virsh qemu-monitor-command ${DOMAIN} --pretty '{ "execute": "query-block" }' will block and no any response, until timeout. This is still excusable.
> But, the disk（drive-virtio-disk0）will occur the same situation：in vm os, the disk will block and no any response.
>
> In other words, when qemu and iscsi-server lose contact, It will cause
> the vm unable.
I haven't tried to reproduce this but I guess QEMU reaches a
synchronization point where it waits for all outstanding requests to
complete. Since the iSCSI target is unresponsive QEMU gets stuck.
These issues can sometimes be fixed by avoiding the synchronization
point (a backtrace should reveal where the main loop thread is stuck)
but other times it really is necessary to wait for all requests and the
solution isn't as obvious.
The QEMU project is currently considering to move its bug tracking to another system. For this we need to know which bugs are still valid and which could be closed already. Thus we are setting older bugs to "Incomplete" now.
If you still think this bug report here is valid, then please switch the state back to "New" within the next 60 days, otherwise this report will be marked as "Expired". Or mark it as "Fix Released" if the problem has been solved with a newer version of QEMU already. Thank you and sorry for the inconvenience.
[Expired for QEMU because there has been no activity for 60 days.]
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