Fastest way to move VM disk to CT Volume

Pedulla · Mar 29, 2022

PVE 7.1-10
I'm moving some VM's to LXC's. They all have large storage disks attached (>4T)
What's the fastest way move the content from the VM's disks to the CT's volume?

bbgeek17 · Mar 29, 2022

Detach the disk from VM and attach it to LXC. Depending on your storage backend you may need to manually rename it and perform other steps.

I suggest you do an end-to-end training run on a non-production VM/volume/CT

Blockbridge: Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

Pedulla · Mar 29, 2022

That sounds too easy... But I've been surprised before.
I'll report back.

Pedulla · Mar 29, 2022

Yeah, not seeing it. Both the VM disk and the CT Volume are on the same zfspool.
Seems like they are two completely different methods of providing storage.

Maybe I'm not be searching for the right words or something.

bbgeek17 · Mar 29, 2022

Well, its not a standard daily operation so there are no readily available solutions that you can just copy-paste.

create new disk and attach it to VM:

pvesm alloc blockbridge 100 vm-100-disk-1 1G
qm set 100 --scsihw virtio-scsi-pci --scsi1 blockbridge:vm-100-disk-1

Inside the VM:

lsblk
NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda       8:0    0  2.2G  0 disk 
├─sda1    8:1    0  2.1G  0 part /
├─sda14   8:14   0    4M  0 part 
└─sda15   8:15   0  106M  0 part /boot/efi
sdb       8:16   0    1G  0 disk 
sr0      11:0    1    4M  0 rom  

mkfs.ext4 /dev/sdb
mkdir /mnt/sdb
mount /dev/sdb /mnt/sdb
echo "hi there from vm" > /mnt/sdb/hi.txt
umount /mnt/sdb

back on the host, unmap the disk from vm:
qm unlink 100 --idlist scsi1

rename the disk using storage specific commands:

bb vss update --vss blockbridge:vm-100-disk-1 --label blockbridge:vm-999-disk-2
== Updated vss: blockbridge:vm-999-disk-2 (VSS1862194C40606620)

attach new disk to the container:

pct set 999 --mp2 blockbridge:vm-999-disk-2,mp=/vmdata

pct config 999
arch: amd64
hostname: CT999
memory: 512
mp1: blockbridge:vm-999-disk-1,mp=/data,size=1G
mp2: blockbridge:vm-999-disk-2,mp=/vmdata,size=1G
ostype: ubuntu
rootfs: blockbridge:vm-999-disk-0,size=8G
swap: 512

PROFIT:

pct start 999
pct exec 999 cat /vmdata/hi.txt
hi there from vm

Blockbridge: Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

Pedulla · Mar 30, 2022

bbgeek17 said:
rename the disk using storage specific commands:
bb vss update --vss blockbridge:vm-100-disk-1 --label blockbridge:vm-999-disk-2 == Updated vss: blockbridge:vm-999-disk-2 (VSS1862194C40606620)

I'm track'n all the way through except for this part.
I've run out of time to work on this today, but I'll keep digg'n.

bbgeek17 · Mar 30, 2022

Pedulla said:
I'm track'n all the way through except for this part.
I've run out of time to work on this today, but I'll keep digg'n.

My example is using Blockbridge storage and as mentioned in the steps :
rename the disk using storage specific commands:

Perhaps this will help:
https://pve.proxmox.com/wiki/Moving_disk_image_from_one_KVM_machine_to_another

Blockbridge: Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

fabian · Mar 30, 2022

with ZFS you won't get around copying the data.. VMs use zvols, CTs use regular filesystem datasets, these are not compatible. for other 'raw'-type storages you might get away with re-using the volumes, if
- they don't have a partition table, but the volume/disk itself is formatted with a filesystem
- that filesystem is ext4

Pedulla · Mar 30, 2022

@fabian, thanks for the confirmation.
Copy it is.

duality · Feb 8, 2024

bbgeek17 said:
Well, its not a standard daily operation so there are no readily available solutions that you can just copy-paste.

create new disk and attach it to VM:
pvesm alloc blockbridge 100 vm-100-disk-1 1G
qm set 100 --scsihw virtio-scsi-pci --scsi1 blockbridge:vm-100-disk-1

Inside the VM:
lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 2.2G 0 disk
├─sda1 8:1 0 2.1G 0 part /
├─sda14 8:14 0 4M 0 part
└─sda15 8:15 0 106M 0 part /boot/efi
sdb 8:16 0 1G 0 disk
sr0 11:0 1 4M 0 rom

mkfs.ext4 /dev/sdb
mkdir /mnt/sdb
mount /dev/sdb /mnt/sdb
echo "hi there from vm" > /mnt/sdb/hi.txt
umount /mnt/sdb

back on the host, unmap the disk from vm:
qm unlink 100 --idlist scsi1

rename the disk using storage specific commands:
bb vss update --vss blockbridge:vm-100-disk-1 --label blockbridge:vm-999-disk-2
== Updated vss: blockbridge:vm-999-disk-2 (VSS1862194C40606620)

attach new disk to the container:
pct set 999 --mp2 blockbridge:vm-999-disk-2,mp=/vmdata

pct config 999
arch: amd64
hostname: CT999
memory: 512
mp1: blockbridge:vm-999-disk-1,mp=/data,size=1G
mp2: blockbridge:vm-999-disk-2,mp=/vmdata,size=1G
ostype: ubuntu
rootfs: blockbridge:vm-999-disk-0,size=8G
swap: 512

PROFIT:
pct start 999
pct exec 999 cat /vmdata/hi.txt
hi there from vm

Blockbridge: Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

thanks for these steps - I just have one issue - Which package contains "bb" command you used here to rename the storage?

bbgeek17 · Feb 8, 2024

duality said:
thanks for these steps - I just have one issue - Which package contains "bb" command you used here to rename the storage?

That command/package is specific to Blockbridge storage. It was used as an example. Your own commands would depend on your storage backend. There are also some limitations as described by @fabian .

Blockbridge: Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

alexskysilk · Feb 8, 2024

Pedulla said:
What's the fastest way move the content from the VM's disks to the CT's volume?

1. detach the disks from their vms.
2. mount the disks on the host eg: /mnt/migrated1
3. pct set <container_id> -mp0 /mnt/migrated,mp=/path/in guest

duality · Feb 8, 2024

I was trying to move a drive from a vm to a ct container - i got it moved but the ct container won't start now. Guessing this won't work?

run_buffer: 322 Script exited with status 32
lxc_init: 844 Failed to run lxc.hook.pre-start for container "104"
__lxc_start: 2027 Failed to initialize container "104"
TASK ERROR: startup for container '104' failed

fabian · Feb 9, 2024

we'd need the full log to tell for sure - but my guess is the prerequisites I posted above are not met (no partition table, but directly ext4 on the image)

duality · Feb 9, 2024

Thanks for all the help, i gave up in the end, reverted the disk back to the original vm, created a new disk and just copied over the data. worked out pretty quick in the end.

This was great steps though. I'm saving it for future!

promok · Dec 6, 2024

duality said:
Thanks for all the help, i gave up in the end, reverted the disk back to the original vm, created a new disk and just copied over the data. worked out pretty quick in the end.

This was great steps though. I'm saving it for future!

How exactly did you copy the data? The UEFI VM has 2 partitions. What commands did you use?

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Fastest way to move VM disk to CT Volume

Pedulla

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bbgeek17

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Pedulla

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bbgeek17

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Pedulla

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