Multi mount protection issue - Slow container startup

[Batto]

Hi everyone,

I think I localized an issue but I can't find a solution.

The situation is simple : for my course I use a Proxmox 6.1.3 to generate virtual machines for my students, so they can have one CT each and snapshots are very useful in this case

My problem is I wrote some scripts to automatised some tasks like duplicate X times a machine, or snap X machines. One script is used to start all the LXC containers I want. As the 3-4 first CT start quickly, it becomes very slow for the others (around 40 seconds each). I took a look in Proxmox /var/log/messages and found the problem :

Dec 11 12:18:37 proxmoxpedago pct[5000]: <root@pam> starting task UPID:proxmoxpedago:000014CD:000276A6:5DF0D08D:vzstart:136:root@pam:
Dec 11 12:18:37 proxmoxpedago pct[5325]: starting CT 136: UPID:proxmoxpedago:000014CD:000276A6:5DF0D08D:vzstart:136:root@pam:
Dec 11 12:18:37 proxmoxpedago systemd[1]: Starting PVE LXC Container: 136...
Dec 11 12:18:37 proxmoxpedago pvestatd[1645]: status update time (47.109 seconds)
Dec 11 12:18:37 proxmoxpedago kernel: EXT4-fs warning (device dm-42): ext4_multi_mount_protect:321: MMP interval 42 higher than expected, please wait.

Dec 11 12:19:00 proxmoxpedago systemd[1]: Starting Proxmox VE replication runner...
Dec 11 12:19:00 proxmoxpedago systemd[1]: pvesr.service: Succeeded.
Dec 11 12:19:00 proxmoxpedago systemd[1]: Started Proxmox VE replication runner.

So apparently, MMP delays starting. I tried to found any information about disabling it but found nothing. Any hint ?

Regards

 

[Richard]

So apparently, MMP delays starting. I tried to found any information about disabling it but found nothing. Any hint ?

mmp should be cotrolled by tune2fs, see related man page (option -E)
How it has effect in that particular case I cannot say. For investigation this it would be necessary to know both storage and container configuration.