Bug 1032369

Summary:	can create live snapshot of passthrough device (iSCSI LUN or block device)
Product:	Red Hat Enterprise Linux 7	Reporter:	Sibiao Luo <sluo>
Component:	qemu-kvm	Assignee:	Jeff Cody <jcody>
Status:	CLOSED WONTFIX	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	7.0	CC:	acathrow, bcao, chayang, juzhang, michen, pbonzini, qzhang, shyu, virt-maint, xfu
Target Milestone:	rc
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:
Clones:	1032393 1034993 (view as bug list)		Environment:
Last Closed:	2014-06-11 18:43:56 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1032393, 1034993, 1073368, 1131974

Description Sibiao Luo 2013-11-20 03:55:37 UTC

Description of problem:
fail to boot guest with pass-through iSCSI LUN specified '-snapshot/snapshot=on'.
But we can create snapshot from a pass-through iSCSI LUN to local file successfully.

Version-Release number of selected component (if applicable):
host info:
3.10.0-50.el7.x86_64
qemu-kvm-rhev-1.5.3-19.el7.x86_64
seabios-1.7.2.2-4.el7.x86_64
guest info:
2.6.32-425.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1.boot guest with pass-through iSCSI LUN specified '-snapshot/snapshot=on'. 
e.g:/usr/libexec/qemu-kvm -M q35 -S -cpu SandyBridge -enable-kvm -m 2048 -smp 2,sockets=2,cores=1,threads=1 -no-kvm-pit-reinjection...-drive file=/dev/disk/by-path/ip-10.66.90.100:3260-iscsi-iqn.2001-05.com.equallogic:0-8a0906-0971f7d03-1dff49b26885073d-s2-sluo-172259-lun-0,if=none,id=drive-data-disk,format=raw,cache=none,aio=native,werror=stop,rerror=stop,snapshot=on -device virtio-scsi-pci,bus=pcie.0,addr=0x7,id=scsi0 -device scsi-block,drive=drive-data-disk,id=data-disk,bus=scsi0.0
2.
3.

Actual results:
after step 1, QEMU will quit with wrong warning message.
(qemu) qemu-kvm: -device scsi-block,drive=drive-data-disk,id=data-disk,bus=scsi0.0: scsi-block: scsi generic interface too old
qemu-kvm: -device scsi-block,drive=drive-data-disk,id=data-disk,bus=scsi0.0: Device initialization failed.
qemu-kvm: -device scsi-block,drive=drive-data-disk,id=data-disk,bus=scsi0.0: Device 'scsi-block' could not be initialized

Expected results:
It should boot up guest successfully with pass-through iSCSI LUN specified '-snapshot/snapshot=on'. 

Additional info:
# /usr/libexec/qemu-kvm -M q35 -S -cpu SandyBridge -enable-kvm -m 2048 -smp 2,sockets=2,cores=1,threads=1 -no-kvm-pit-reinjection -usb -device usb-tablet,id=input0 -name sluo -uuid 990ea161-6b67-47b2-b803-19fb01d30d10 -rtc base=localtime,clock=host,driftfix=slew -device virtio-serial-pci,id=virtio-serial0,max_ports=16,vectors=0,bus=pcie.0,addr=0x3 -chardev socket,id=channel1,path=/tmp/helloworld1,server,nowait -device virtserialport,chardev=channel1,name=com.redhat.rhevm.vdsm,bus=virtio-serial0.0,id=port1 -chardev socket,id=channel2,path=/tmp/helloworld2,server,nowait -device virtserialport,chardev=channel2,name=com.redhat.rhevm.vdsm,bus=virtio-serial0.0,id=port2 -drive file=/home/RHEL6.5-20131019.1_Server_x86_64.qcow2bk,if=none,id=drive-virtio-disk,format=qcow2,cache=none,aio=native,werror=stop,rerror=stop -device virtio-blk-pci,vectors=0,bus=pcie.0,addr=0x4,scsi=off,drive=drive-virtio-disk,id=virtio-disk,bootindex=1 -netdev tap,id=hostnet0,vhost=on,script=/etc/qemu-ifup -device rtl8139,netdev=hostnet0,id=virtio-net-pci0,mac=00:01:02:03:04:05,bus=pcie.0,addr=0x5 -device virtio-balloon-pci,id=ballooning,bus=pcie.0,addr=0x6 -global PIIX4_PM.disable_s3=0 -global PIIX4_PM.disable_s4=0 -drive file=/dev/disk/by-path/ip-10.66.90.100:3260-iscsi-iqn.2001-05.com.equallogic:0-8a0906-0971f7d03-1dff49b26885073d-s2-sluo-172259-lun-0,if=none,id=drive-data-disk,format=raw,cache=none,aio=native,werror=stop,rerror=stop,snapshot=on -device virtio-scsi-pci,bus=pcie.0,addr=0x7,id=scsi0 -device scsi-block,drive=drive-data-disk,id=data-disk,bus=scsi0.0 -k en-us -boot menu=on -qmp tcp:0:4444,server,nowait -serial unix:/tmp/ttyS0,server,nowait -vnc :1 -spice disable-ticketing,port=5931 -monitor stdio

Comment 1 Paolo Bonzini 2013-11-20 12:35:12 UTC

"-snapshot/snapshot=on" are not supposed to work with iSCSI LUNs or scsi-block.

The bug is actually that we can create a live snapshot of a passthrough device.

Comment 2 Sibiao Luo 2013-12-02 06:11:05 UTC

If use libiscsi has not reproduced this issue.
e.g:...-drive file=iscsi://10.66.6.82:3260/iqn.2013-11.com.example:storage.disk1.juli.xyz/2,if=none,id=drive-data-disk,readonly=on,snapshot=on,serial=sluo-disk -device virtio-blk-pci,bus=pci.0,addr=0x7,drive=drive-data-disk,id=data-disk -iscsi id=iqn-sluo
(qemu) info block
drive-data-disk: removable=0 io-status=ok file=/tmp/vl.9W69qb backing_file=iscsi://10.66.6.82:3260/iqn.2013-11.com.example:storage.disk1.juli.xyz/2 backing_file_depth=1 ro=0 drv=qcow2 encrypted=0 bps=0 bps_rd=0 bps_wr=0 iops=0 iops_rd=0 iops_wr=0

Best Regards,
sluo

Comment 3 Paolo Bonzini 2013-12-02 10:30:15 UTC

You're not using a passthrough device (virtio-blk-pci).  snapshot=on + libiscsi is a valid combination in general.  It is snapshot=on + scsi-block that is invalid.

Comment 5 Ademar Reis 2014-06-11 18:43:56 UTC

From https://bugzilla.redhat.com/show_bug.cgi?id=1032393#c4 (RHEL6 clone):

"Libvirt doesn't use -snapshot (or snapshot=on), so refusing to support it in qemu should have no impact on libvirt."

Closing as WONTFIX in RHEL7 because we don't support direct usage of qemu-kvm