Snapshot of VM Freezes All Other VMs on Node

A

asummere

New Member
Jan 27, 2026
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Hi all,

I'm running PVE 9.1.2. Whenever I do a snapshot of a VM, I notice that all other VMs on the node same to freeze as well. As soon as the snapshot completes, the other VMs resume as normal. Is this normal behavior? I cannot find reference to this; I would think that only the VM getting the snapshot done would be the one to freeze.

Thank you!
 
Hi @bbgeek17 , thanks for the response.

For storage, the server is running SAS drives in a RAID-5 with local-lvm as LVM-Thin. Each VM is running storage as VirtIO SCSI single. If that isn't the information you were looking for, please let me know.

Thank you!
 
It may be helpful for the community if you provide the following:

cat /etc/pve/storage.cfg
pvesm status
lsblk
pvs
vgs
lvs
qm list
qm config [vm_id_snapshotted]
- task output of the snapshot
- journalctl output +-1min around snapshot
- dmesg (around snapshot)
- what led you to believe the other VMs are frozen
- is the snapshot being taken of Live VM? Is RAM state included?

Keep in mind that less modern systems may not be able to handle the load, particularly to storage as efficiently as newer ones. It is unlikely that you've come across a bug in PVE system, albeit not impossible.

I would recommend experimenting with various types of snapshots (Live, offline, RAM and no-RAM, fewest amount of load/VMs running ) to try to reduce the number of variables.

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox
 
- what led you to believe the other VMs are frozen - If I, or others, are working in any of the other VMs when a snapshot is being done, it hangs while the snapshot is being done, and then resumes normal operation once the snapshot is complete.

- is the snapshot being taken of Live VM? Is RAM state included? Yes, it is being taken of the live VM, and yes, the RAM state is included.

dmesg is too large to post, was there anything specific you were looking for in it that I can extract from it? anything storage related?

Code: 
root@proxmox-2:/# cat /etc/pve/storage.cfg
dir: local
        path /var/lib/vz
        content import,backup,iso,vztmpl

lvmthin: local-lvm
        thinpool data
        vgname pve
        content images,rootdir
Code: 
root@proxmox-2:/# pvesm status
Name               Type     Status     Total (KiB)      Used (KiB) Available (KiB)        %
local               dir     active        98497780        11010364        82437868   11.18%
local-lvm       lvmthin     active      3353337856       347741135      3005596720   10.37%
Code: 
root@proxmox-2:/# lsblk
NAME                                                      MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
sda                                                         8:0    0  3.3T  0 disk
├─sda1                                                      8:1    0 1007K  0 part
├─sda2                                                      8:2    0    1G  0 part /boot/efi
└─sda3                                                      8:3    0  3.3T  0 part
  ├─pve-swap                                              252:0    0    8G  0 lvm  [SWAP]
  ├─pve-root                                              252:1    0   96G  0 lvm  /
  ├─pve-data_tmeta                                        252:2    0 15.9G  0 lvm
  │ └─pve-data-tpool                                      252:4    0  3.1T  0 lvm
  │   ├─pve-data                                          252:5    0  3.1T  1 lvm
  │   ├─pve-vm--103--disk--1                              252:6    0   50G  0 lvm
  │   ├─pve-vm--103--disk--0                              252:7    0    4M  0 lvm
  │   ├─pve-vm--106--disk--1                              252:8    0  200G  0 lvm
  │   ├─pve-vm--106--disk--0                              252:9    0    4M  0 lvm
  │   ├─pve-vm--102--disk--1                              252:10   0   32G  0 lvm
  │   ├─pve-vm--102--disk--0                              252:11   0    4M  0 lvm
  │   ├─pve-vm--104--disk--1                              252:12   0  150G  0 lvm
  │   ├─pve-vm--104--disk--0                              252:13   0    4M  0 lvm
  │   ├─pve-vm--101--disk--1                              252:14   0   20G  0 lvm
  │   ├─pve-vm--101--disk--0                              252:15   0    4M  0 lvm
  │   ├─pve-vm--100--disk--1                              252:16   0  100G  0 lvm
  │   ├─pve-vm--105--disk--0                              252:17   0    4M  0 lvm
  │   ├─pve-vm--105--disk--1                              252:18   0  150G  0 lvm
  │   ├─pve-vm--103--state--Before--Updates--2026--01--27 252:19   0  8.5G  0 lvm
  │   ├─pve-vm--101--state--Before--Updates--2026--01--15 252:20   0 16.5G  0 lvm
  │   ├─pve-vm--104--state--Before--Updates--2026--01--27 252:21   0 32.5G  0 lvm
  │   ├─pve-vm--105--state--Before--Updates--2026--01--06 252:22   0 64.5G  0 lvm
  │   └─pve-vm--106--state--Before--Updates--2026--01--15 252:23   0 32.5G  0 lvm
  └─pve-data_tdata                                        252:3    0  3.1T  0 lvm
    └─pve-data-tpool                                      252:4    0  3.1T  0 lvm
      ├─pve-data                                          252:5    0  3.1T  1 lvm
      ├─pve-vm--103--disk--1                              252:6    0   50G  0 lvm
      ├─pve-vm--103--disk--0                              252:7    0    4M  0 lvm
      ├─pve-vm--106--disk--1                              252:8    0  200G  0 lvm
      ├─pve-vm--106--disk--0                              252:9    0    4M  0 lvm
      ├─pve-vm--102--disk--1                              252:10   0   32G  0 lvm
      ├─pve-vm--102--disk--0                              252:11   0    4M  0 lvm
      ├─pve-vm--104--disk--1                              252:12   0  150G  0 lvm
      ├─pve-vm--104--disk--0                              252:13   0    4M  0 lvm
      ├─pve-vm--101--disk--1                              252:14   0   20G  0 lvm
      ├─pve-vm--101--disk--0                              252:15   0    4M  0 lvm
      ├─pve-vm--100--disk--1                              252:16   0  100G  0 lvm
      ├─pve-vm--105--disk--0                              252:17   0    4M  0 lvm
      ├─pve-vm--105--disk--1                              252:18   0  150G  0 lvm
      ├─pve-vm--103--state--Before--Updates--2026--01--27 252:19   0  8.5G  0 lvm
      ├─pve-vm--101--state--Before--Updates--2026--01--15 252:20   0 16.5G  0 lvm
      ├─pve-vm--104--state--Before--Updates--2026--01--27 252:21   0 32.5G  0 lvm
      ├─pve-vm--105--state--Before--Updates--2026--01--06 252:22   0 64.5G  0 lvm
      └─pve-vm--106--state--Before--Updates--2026--01--15 252:23   0 32.5G  0 lvm
Code: 
root@proxmox-2:/# pvs
  PV         VG  Fmt  Attr PSize PFree
  /dev/sda3  pve lvm2 a--  3.27t <16.25g
Code: 
root@proxmox-2:/# vgs
  VG  #PV #LV #SN Attr   VSize VFree
  pve   1  32   0 wz--n- 3.27t <16.25g
Code: 
root@proxmox-2:/# lvs
  LV                                           VG  Attr       LSize   Pool Origin        Data%  Meta%  Move Log Cpy%Sync Convert
  data                                         pve twi-aotz--   3.12t                    10.37  0.87                          
  root                                         pve -wi-ao----  96.00g                                                          
  snap_vm-101-disk-0_Before-Updates-2026-01-15 pve Vri---tz-k   4.00m data vm-101-disk-0                                      
  snap_vm-101-disk-1_Before-Updates-2026-01-15 pve Vri---tz-k  20.00g data vm-101-disk-1                                      
  snap_vm-103-disk-0_Before-Updates-2026-01-27 pve Vri---tz-k   4.00m data vm-103-disk-0                                      
  snap_vm-103-disk-1_Before-Updates-2026-01-27 pve Vri---tz-k  50.00g data vm-103-disk-1                                      
  snap_vm-104-disk-0_Before-Updates-2026-01-27 pve Vri---tz-k   4.00m data vm-104-disk-0                                      
  snap_vm-104-disk-1_Before-Updates-2026-01-27 pve Vri---tz-k 150.00g data vm-104-disk-1                                      
  snap_vm-105-disk-0_Before-Updates-2026-01-06 pve Vri---tz-k   4.00m data vm-105-disk-0                                      
  snap_vm-105-disk-1_Before-Updates-2026-01-06 pve Vri---tz-k 150.00g data vm-105-disk-1                                      
  snap_vm-106-disk-0_Before-Updates-2026-01-15 pve Vri---tz-k   4.00m data vm-106-disk-0                                      
  snap_vm-106-disk-1_Before-Updates-2026-01-15 pve Vri---tz-k 200.00g data vm-106-disk-1                                      
  swap                                         pve -wi-ao----   8.00g                                                          
  vm-100-disk-0                                pve Vwi---tz--   4.00m data                                                    
  vm-100-disk-1                                pve Vwi-a-tz-- 100.00g data               4.78                                  
  vm-101-disk-0                                pve Vwi-aotz--   4.00m data               14.06                                
  vm-101-disk-1                                pve Vwi-aotz--  20.00g data               49.00                                
  vm-101-state-Before-Updates-2026-01-15       pve Vwi-a-tz-- <16.49g data               32.92                                
  vm-102-disk-0                                pve Vwi-aotz--   4.00m data               14.06                                
  vm-102-disk-1                                pve Vwi-aotz--  32.00g data               33.21                                
  vm-103-disk-0                                pve Vwi-aotz--   4.00m data               14.06                                
  vm-103-disk-1                                pve Vwi-aotz--  50.00g data               54.44                                
  vm-103-state-Before-Updates-2026-01-27       pve Vwi-a-tz--  <8.49g data               39.97                                
  vm-104-disk-0                                pve Vwi-aotz--   4.00m data               14.06                                
  vm-104-disk-1                                pve Vwi-aotz-- 150.00g data               51.21                                
  vm-104-state-Before-Updates-2026-01-27       pve Vwi-a-tz-- <32.49g data               69.99                                
  vm-105-disk-0                                pve Vwi-aotz--   4.00m data               14.06                                
  vm-105-disk-1                                pve Vwi-aotz-- 150.00g data               42.52                                
  vm-105-state-Before-Updates-2026-01-06       pve Vwi-a-tz-- <64.49g data               35.99                                
  vm-106-disk-0                                pve Vwi-aotz--   4.00m data               14.06                                
  vm-106-disk-1                                pve Vwi-aotz-- 200.00g data               11.91                                
  vm-106-state-Before-Updates-2026-01-15       pve Vwi-a-tz-- <32.49g data               52.51
Code: 
root@proxmox-2:/# qm list
      VMID NAME                 STATUS     MEM(MB)    BOOTDISK(GB) PID      
       100 TRFWOWZA             stopped    32768              0.00 0        
       101 TRFAL02              running    8192              20.00 1755    
       102 pfSense              running    8192              32.00 1550    
       103 TRFAL01              running    4096              50.00 3289356  
       104 TRFAL03              running    16384            150.00 156939  
       105 TRFWIN02             running    32768            150.00 243707  
       106 TRFUL01              running    16384            200.00 1430
Code: 
root@proxmox-2:/# qm config 101
agent: 1
bios: ovmf
boot: order=sata0;scsi0
cores: 1
cpu: x86-64-v3
efidisk0: local-lvm:vm-101-disk-0,efitype=4m,size=4M
memory: 8192
meta: creation-qemu=10.1.2,ctime=1765311310
name: TRFAL02
net0: virtio=00:0c:29:b7:db:26,bridge=vmbr0
onboot: 1
ostype: l26
parent: Before-Updates-2026-01-15
sata0: none,media=cdrom
scsi0: local-lvm:vm-101-disk-1,size=20G
scsihw: virtio-scsi-single
smbios1: uuid=564d990f-0a3a-d92f-7575-c01773b7db26
sockets: 4
startup: order=6
vmgenid: 3374c61e-1add-4854-bdeb-4c96ab085648
Code: 
  Logical volume "vm-101-state-Before-Updates-2026-01-27" created.
  Logical volume pve/vm-101-state-Before-Updates-2026-01-27 changed.
saving VM state and RAM using storage 'local-lvm'
319.00 B in 0s
578.50 MiB in 1s
1.68 GiB in 2s
2.77 GiB in 3s
3.87 GiB in 4s
completed saving the VM state in 4s, saved 4.13 GiB
snapshotting 'drive-scsi0' (local-lvm:vm-101-disk-1)
  Logical volume "snap_vm-101-disk-1_Before-Updates-2026-01-27" created.
snapshotting 'drive-efidisk0' (local-lvm:vm-101-disk-0)
  Logical volume "snap_vm-101-disk-0_Before-Updates-2026-01-27" created.
TASK OK
Code: 
root@proxmox-2:/# journalctl -f

Jan 27 10:32:00 proxmox-2 pvedaemon[4120274]: <asummere@pve> starting task UPID:proxmox-2:003F185A:15E0C9E0:6978F690:qmsnapshot:101:asummere@pve:
Jan 27 10:32:00 proxmox-2 pvedaemon[4135002]: <asummere@pve> snapshot VM 101: Before-Updates-2026-01-27
Jan 27 10:32:26 proxmox-2 dmeventd[491]: No longer monitoring thin pool pve-data-tpool.
Jan 27 10:32:26 proxmox-2 dmeventd[491]: Monitoring thin pool pve-data-tpool.
Jan 27 10:32:26 proxmox-2 dmeventd[491]: No longer monitoring thin pool pve-data-tpool.
Jan 27 10:32:26 proxmox-2 dmeventd[491]: Monitoring thin pool pve-data-tpool.
Jan 27 10:32:26 proxmox-2 pvedaemon[4120274]: <asummere@pve> end task UPID:proxmox-2:003F185A:15E0C9E0:6978F690:qmsnapshot:101:asummere@pve: OK
 
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asummere said:
- is the snapshot being taken of Live VM? Is RAM state included? Yes, it is being taken of the live VM, and yes, the RAM state is included.
Click to expand...
It’s possible that you’re experiencing what is commonly referred to as “VM stunning.” In many virtualization environments (ESXi, PVE, etc.) it is most often caused by slow or congested storage.

As suggested earlier, try performing the operation without a RAM snapshot. That should give you a good indication one way or the other.

You can then follow up by monitoring I/O using native Linux tools to validate this theory.

At the end of the day, the primary common dependency across all of your affected VMs is storage.

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox
 
What models are those disks? (lsblk -o+FSTYPE,MODEL) Can you try if it happens if the VM has no existing snapshots and also without RAM? Likely unrelated but you should also look into discard.
 
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