KRBD 0 Ceph prevents VMs from starting

jepper

New Member
Oct 2, 2025
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I have a ceph squid cluster installed separately (with cephadm) and added to my proxmox cluster using the Datacenter/Storage pane. Native proxmox Ceph is not enabled.

I can only boot VMs when KRBD is enabled. I would like to disable it, so I can enable PWL. But when I disable KRBD, and turn on any VM, proxmox throws

kvm: -blockdev {"detect-zeroes":"on","discard":"ignore","driver":"throttle","file":{"cache":{"direct":true,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"raw","file":{"auth-client-required":["cephx"],"cache":{"direct":true,"no-flush":false},"conf":"/etc/pve/priv/ceph/ceph-metal.conf","detect-zeroes":"on","discard":"ignore","driver":"rbd","image":"vm-103-disk-2","node-name":"e6c5a00bb877016fc68a29f1bd66a1b","pool":"pool1","read-only":false,"server":[{"host":"10.112.212.71","port":"6789"},{"host":"10.112.212.72","port":"6789"}],"user":"admin"},"node-name":"f6c5a00bb877016fc68a29f1bd66a1b","read-only":false},"node-name":"drive-virtio0","read-only":false,"throttle-group":"throttle-drive-virtio0"}: error connecting: No such file or directory
TASK ERROR: start failed: QEMU exited with code 1

Using rbd, I can see the storage:
Bash:
root@lab6:~# rbd ls pool1|grep vm-103-disk-2
vm-103-disk-2

I'm at loss as to where to start troubleshooting this.
 
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Is that the output from the task log?

What output do you get if you try to start the VM from the CLI?
qm start <VMID>
 
Is that the output from the task log?

What output do you get if you try to start the VM from the CLI?
qm start <VMID>
The error in the initial post is from the web interface Tasks log.
Similar output when I run from cli:
root@lab6:~# qm start 103
kvm: -blockdev {"detect-zeroes":"on","discard":"ignore","driver":"throttle","file":{"cache":{"direct":true,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"raw","file":{"auth-client-required":["cephx"],"cache":{"direct":true,"no-flush":false},"conf":"/etc/pve/priv/ceph/ceph-metal.conf","detect-zeroes":"on","discard":"ignore","driver":"rbd","image":"vm-103-disk-2","node-name":"e6c5a00bb877016fc68a29f1bd66a1b","pool":"pool1","read-only":false,"server":[{"host":"10.112.212.71","port":"6789"},{"host":"10.112.212.72","port":"6789"}],"user":"admin"},"node-name":"f6c5a00bb877016fc68a29f1bd66a1b","read-only":false},"node-name":"drive-virtio0","read-only":false,"throttle-group":"throttle-drive-virtio0"}: error connecting: No such file or directory
start failed: QEMU exited with code 1
 
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please post:

- pveversion -v
- cat /etc/pve/storage.cfg
- cat /etc/pve/priv/ceph/ceph-metal.conf
- cat /etc/ceph/ceph.conf

please censor any sensitive data such as auth keys
 
please post:

- pveversion -v
- cat /etc/pve/storage.cfg
- cat /etc/pve/priv/ceph/ceph-metal.conf
- cat /etc/ceph/ceph.conf

please censor any sensitive data such as auth keys
# pveversion -v
proxmox-ve: 9.1.0 (running kernel: 6.17.2-2-pve)
pve-manager: 9.1.2 (running version: 9.1.2/9d436f37a0ac4172)
proxmox-kernel-helper: 9.0.4
proxmox-kernel-6.17.2-2-pve-signed: 6.17.2-2
proxmox-kernel-6.17: 6.17.2-2
proxmox-kernel-6.14.11-4-pve-signed: 6.14.11-4
proxmox-kernel-6.14: 6.14.11-4
proxmox-kernel-6.14.8-2-pve-signed: 6.14.8-2
amd64-microcode: 3.20250311.1
ceph-fuse: 19.2.3-pve2
corosync: 3.1.9-pve2
criu: 4.1.1-1
frr-pythontools: 10.4.1-1+pve1
ifupdown2: 3.3.0-1+pmx11
ksm-control-daemon: 1.5-1
libjs-extjs: 7.0.0-5
libproxmox-acme-perl: 1.7.0
libproxmox-backup-qemu0: 2.0.1
libproxmox-rs-perl: 0.4.1
libpve-access-control: 9.0.4
libpve-apiclient-perl: 3.4.2
libpve-cluster-api-perl: 9.0.7
libpve-cluster-perl: 9.0.7
libpve-common-perl: 9.1.0
libpve-guest-common-perl: 6.0.2
libpve-http-server-perl: 6.0.5
libpve-network-perl: 1.2.3
libpve-rs-perl: 0.11.3
libpve-storage-perl: 9.1.0
libspice-server1: 0.15.2-1+b1
lvm2: 2.03.31-2+pmx1
lxc-pve: 6.0.5-3
lxcfs: 6.0.4-pve1
novnc-pve: 1.6.0-3
proxmox-backup-client: 4.1.0-1
proxmox-backup-file-restore: 4.1.0-1
proxmox-backup-restore-image: 1.0.0
proxmox-firewall: 1.2.1
proxmox-kernel-helper: 9.0.4
proxmox-mail-forward: 1.0.2
proxmox-mini-journalreader: 1.6
proxmox-offline-mirror-helper: 0.7.3
proxmox-widget-toolkit: 5.1.2
pve-cluster: 9.0.7
pve-container: 6.0.18
pve-docs: 9.1.1
pve-edk2-firmware: 4.2025.05-2
pve-esxi-import-tools: 1.0.1
pve-firewall: 6.0.4
pve-firmware: 3.17-2
pve-ha-manager: 5.0.8
pve-i18n: 3.6.5
pve-qemu-kvm: 10.1.2-4
pve-xtermjs: 5.5.0-3
qemu-server: 9.1.1
smartmontools: 7.4-pve1
spiceterm: 3.4.1
swtpm: 0.8.0+pve3
vncterm: 1.9.1
zfsutils-linux: 2.3.4-pve1

# cat /etc/pve/storage.cfg
dir: local
path /var/lib/vz
content images,iso,backup,vztmpl,snippets
shared 0

rbd: ceph-metal
content rootdir,images
krbd 0
monhost 10.112.212.71:6789,10.112.212.72:6789
pool pool1
username admin

# cat /etc/pve/priv/ceph/ceph-metal.conf
[global]
fsid = 1216xx
mon_host = [v2:10.112.212.71:3300/0,v1:10.112.212.71:6789/0] [v2:10.112.212.72:3300/0,v1:10.112.212.72:6789/0]

# cat /etc/ceph/ceph.conf (it's a symlink from /etc/pve/priv/ceph/ceph-metal.conf)
[global]
fsid = 1216xx
mon_host = [v2:10.112.212.71:3300/0,v1:10.112.212.71:6789/0] [v2:10.112.212.72:3300/0,v1:10.112.212.72:6789/0]
 
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monhost 10.112.212.71:6789,10.112.212.72:6789
As a first guess, I don't think you should add the ports here. Can you try it with just the IPs in the storage config?

And please use the code block formatting that usually makes reading output a lot nicer :)