Backup VM with 2 disks or more

[AlexKir]

Hello!

May be, it stupid question.

Help me, I want to understand.
How does vzdump make backup of vm with more than 1 disk?
I use shared LVM storage.

Variant1:
1. create snapshot disks
2. backup
3. delete snapshot

Variant2:
1. create snapshot disk 1
2. backup disk 1
3. create snapshot disk 2
4. backup disk 2
5. ...

if variant2 is "true". What about consistensy?

 

[dcsapak]

for vms it is different altogether

it makes a qemu-internal snapshot (not a storage one) and writes disk-blocks out of order as they would get overwritten from the guest

a more detailed description is here:

https://git.proxmox.com/?p=pve-qemu...377bd1821479259e81d4e78d;hb=refs/heads/master

 

[AlexKir]

for vms it is different altogether
https://git.proxmox.com/?p=pve-qemu...377bd1821479259e81d4e78d;hb=refs/heads/master

I read, but not found answer.

it makes a qemu-internal snapshot

It makes snapshot all disks and then make backup
or
it makes snapshot first disk and than make backup then make snapshot second disk and add it to backup

 

[dcsapak]

It makes snapshot all disks and then make backup

this

 

[AlexKir]

Thanks!

 

[AlexKir]

Hello!

I made test.

I created vm:

Spoiler

agent: 1
boot: cdn
bootdisk: scsi0
cores: 2
cpu: Westmere,flags=+pcid
ide2: none,media=cdrom
memory: 4096
name: testfe-bkp
net0: virtio=C6:73:7F:8F:AD:4E,bridge=vmbr0,tag=261
numa: 0
ostype: l26
scsi0: vm_shared7:vm-576-disk-0,cache=writethrough,size=50G
scsi1: vm_shared7:vm-576-disk-1,cache=writethrough,size=32G
scsihw: virtio-scsi-single
smbios1: uuid=b4657518-12eb-4c36-a4f1-0a1c0adb332b
sockets: 1

I started backup and then created 2 files.

test-bpk:~ # touch /disk1/backup.txt /disk2/backup.txt
test-bkp:~ # ll /disk1/backup.txt /disk2/backup.txt
-rw-r----- 1 root root 0 Jun 26 09:32 /disk1/backup.txt
-rw-r----- 1 root root 0 Jun 26 09:32 /disk2/backup.txt

Backup log:

Spoiler

INFO: starting new backup job: vzdump 576 --remove 0 --node che-pve4-09 --mode snapshot --storage backup-nas03 --compress lzo
INFO: Starting Backup of VM 576 (qemu)
INFO: Backup started at 2019-06-26 09:32:38
INFO: status = running
INFO: update VM 576: -lock backup
INFO: VM Name: test-bkp
INFO: include disk 'scsi0' 'vm_shared7:vm-576-disk-0' 50G
INFO: include disk 'scsi1' 'vm_shared7:vm-576-disk-1' 32G
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO: creating archive '/mnt/pve/backup-nas03/dump/vzdump-qemu-576-2019_06_26-09_32_38.vma.lzo'
Qemu Guest Agent is not running - VM 576 qmp command 'guest-ping' failed - got timeout
INFO: started backup task 'd870cb09-30ad-49f5-8faf-6fdd22aa865b'
INFO: status: 0% (315490304/88046829568), sparse 0% (96714752), duration 3, read/write 105/72 MB/s
INFO: status: 1% (938606592/88046829568), sparse 0% (103837696), duration 8, read/write 124/123 MB/s
INFO: status: 100% (88046829568/88046829568), sparse 51% (45114052608), duration 692, read/write 84/63 MB/s
INFO: transferred 88046 MB in 692 seconds (127 MB/s)
INFO: archive file size: 20.92GB
INFO: Finished Backup of VM 576 (00:11:39)
INFO: Backup finished at 2019-06-26 09:44:17
INFO: Backup job finished successfully
TASK OK

I restored VM from backup and I have file on second disk
test-bkp:~ # ll /disk1/backup.txt /disk2/backup.txt
ls: cannot access '/disk1/backup.txt': No such file or directory
-rw-r----- 1 root root 0 Jun 26 09:32 /disk2/backup.txt

It strange for me.
I expected no files on both disks.

Where did I mistake?