problem with hotplug and 64GB ram

lexz · May 11, 2022

We are seeing exactly the same issue
TASK ERROR: memory size (65536) must be aligned to 2048 for hotplugging

Matyi.Szabolcs · Sep 22, 2022

Hi!

The problem is still there in Proxmox 7.2-11
If the memory hotplug is activated, I get a kernel panic after a reboot.
The problem does not occur with Ubuntu VM, only with Almalinux and Rockylinux.
I tried several kernel versions, but there was a kernel panic with all of them.

I also often encounter such errors:
TASK ERROR: memory size (65536) must be aligned to 2048 for hotplugging

Thanks!

leesteken · Sep 22, 2022

With Linux Mint 21 you cannot boot (because of memory deadlock) with memory hotplug and more than 21GB. Adding more memory later works fine.

Faber Gallego · Mar 7, 2023

z00te said:
hi, i am having problems with some test vm with 64GB Ram and hotplug (no probs with 32GB and until 45056 MiB).
simply the vm refuse to start with the error :

TASK ERROR: memory size (65536) must be aligned to 2048 for hotplugging

there are no other vm on the proxmox
free -m total used free shared buff/cache available Mem: 515644 4616 510466 80 561 509192 Swap: 16383 0 16383

proxmox updated to:
proxmox-ve: 6.2-1 (running kernel: 5.4.44-2-pve)
pve-manager: 6.2-10 (running version: 6.2-10/a20769ed)
....

there are some restriction to use memory hotplug and vm with a lot of ram?

DOS ALTERNATIVAS:
A-> En modulo de administracion web de la maquina virtual --> Options --> Hotplug-->edit--> ("Deshabilita todo") ----> start

B-> En modulo de administracion web de la maquina virtual --> Hardware--> Memory-->edit--> ("Quitar opcion balloon device") ----> start

Despues del correcto arranque de la maquina virtual , procedemos apagar la maquina virtual y nuevamente podriamos configurar las opciones deshabilitadas.

ruta de la configuracion de la MV -------> /etc/pve/qemu-server/"id maquina.conf"

Faber Gallego · Mar 7, 2023

mishki said:
Sí
View attachment 29241

ALTERNATIVAS:
A-> En modulo de administracion web de la maquina virtual --> Options --> Hotplug-->edit--> ("Deshabilita todo") ----> start

B-> En modulo de administracion web de la maquina virtual --> Hardware--> Memory-->edit--> ("Quitar opcion balloon device") ----> start

Despues del correcto arranque de la maquina virtual , procedemos apagar la maquina virtual y nuevamente podriamos configurar las opciones deshabilitadas.

ruta de la configuracion de la MV -------> /etc/pve/qemu-server/"id maquina.conf"

Faber Gallego · Mar 7, 2023

Tacioandrade said:
En realidad estoy usando 4098 MB y no 4096, error al calcular. jeje
View attachment 29224
Y en la máquina física hay 80 vcore y 256 GB de RAM que solo uso el 5% de la potencia computacional.

ALTERNATIVAS:
A-> En modulo de administracion web de la maquina virtual --> Options --> Hotplug-->edit--> ("Deshabilita todo") ----> start

B-> En modulo de administracion web de la maquina virtual --> Hardware--> Memory-->edit--> ("Quitar opcion balloon device") ----> start

Despues del correcto arranque de la maquina virtual , procedemos apagar la maquina virtual y nuevamente podriamos configurar las opciones deshabilitadas.

ruta de la configuracion de la MV -------> /etc/pve/qemu-server/"id maquina.conf"

mishki said:
Sí
View attachment 29241

ALTERNATIVAS:
A-> En modulo de administracion web de la maquina virtual --> Options --> Hotplug-->edit--> ("Deshabilita todo") ----> start

B-> En modulo de administracion web de la maquina virtual --> Hardware--> Memory-->edit--> ("Quitar opcion balloon device") ----> start

Despues del correcto arranque de la maquina virtual , procedemos apagar la maquina virtual y nuevamente podriamos configurar las opciones deshabilitadas.

ruta de la configuracion de la MV -------> /etc/pve/qemu-server/"id maquina.conf"

Faber Gallego · Mar 7, 2023

Tacioandrade said:
En realidad estoy usando 4098 MB y no 4096, error al calcular. jeje
View attachment 29224
Y en la máquina física hay 80 vcore y 256 GB de RAM que solo uso el 5% de la potencia computacional.

ALTERNATIVAS:
A-> En modulo de administracion web de la maquina virtual --> Options --> Hotplug-->edit--> ("Deshabilita todo") ----> start

B-> En modulo de administracion web de la maquina virtual --> Hardware--> Memory-->edit--> ("Quitar opcion balloon device") ----> start

Despues del correcto arranque de la maquina virtual , procedemos apagar la maquina virtual y nuevamente podriamos configurar las opciones deshabilitadas.

ruta de la configuracion de la MV -------> /etc/pve/qemu-server/"id maquina.conf"

z00te said:
hola, estoy teniendo problemas con algunas máquinas virtuales de prueba con 64 GB de RAM y hotplug (sin problemas con 32 GB y hasta 45056 MiB).
simplemente el vm se niega a comenzar con el error:

ERROR DE TAREA: el tamaño de la memoria (65536) debe estar alineado con 2048 para la conexión en caliente

no hay otra máquina virtual en el proxmox
libre -m caché/búfer compartido gratuito total utilizado disponible Mem: 515644 4616 510466 80 561 509192 Intercambio: 16383 0 16383

proxmox actualizado a:
proxmox-ve: 6.2-1 (núcleo en ejecución: 5.4.44-2-pve)
pve-manager: 6.2-10 (versión en ejecución: 6.2-10/a20769ed)
....

¿Hay alguna restricción para usar memoria hotplug y vm con mucha ram?

ALTERNATIVAS:
A-> En modulo de administracion web de la maquina virtual --> Options --> Hotplug-->edit--> ("Deshabilita todo") ----> start

B-> En modulo de administracion web de la maquina virtual --> Hardware--> Memory-->edit--> ("Quitar opcion balloon device") ----> start

Despues del correcto arranque de la maquina virtual , procedemos apagar la maquina virtual y nuevamente podriamos configurar las opciones deshabilitadas.

ruta de la configuracion de la MV -------> /etc/pve/qemu-server/"id maquina.conf"

spirit · Mar 8, 2023

Hi,

we are currently working to improve memory hotplug, where you'll be able to define maxmemory and also virtio-mem support.

I think it should solve all yours problem.

It should be available in coming weeks.

Orkhan · Mar 16, 2023

spirit said:
Hi,

we are currently working to improve memory hotplug, where you'll be able to define maxmemory and also virtio-mem support.

I think it should solve all yours problem.

It should be available in coming weeks.

Hello!

Maybe any news about this?

spirit · Mar 16, 2023

Orkhan said:
Hello!

Maybe any news about this?

patches are already sent to the dev mailing list, waiting to merge.
(I think that 7.4 should come soon, just need to wait a little bit

Orkhan · Mar 26, 2023

Hello!

We upgrade PVE version to 7.4-3. And when we assign 60 GB RAM get error:

Code:

generating cloud-init ISO
TASK ERROR: memory size (61440) must be aligned to 2048 for hotplugging

leesteken · Mar 26, 2023

Orkhan said:
We upgrade PVE version to 7.4-3. And when we assign 60 GB RAM get error:

Code:

generating cloud-init ISO TASK ERROR: memory size (61440) must be aligned to 2048 for hotplugging

Maybe this post can help https://forum.proxmox.com/threads/vm-windows-cannot-start-with-ram-more-48gb.76617/post-340914? Try 59GB or 61GB.

Orkhan · Mar 26, 2023

Hello!

Thank you, we do it and get this:

Code:

generating cloud-init ISO
kvm: -device pc-dimm,id=dimm62,memdev=mem-dimm62,node=0: a used vhost backend has no free memory slots left
TASK ERROR: start failed: QEMU exited with code 1

Can you say it's critical problem? Maybe we simple turn of memory from HotPlug menu and use VM? Hm?

leesteken · Mar 26, 2023

Orkhan said:
kvm: -device pc-dimm,id=dimm62,memdev=mem-dimm62,node=0: a used vhost backend has no free memory slots left

Maybe this post can help https://forum.proxmox.com/threads/u...vms-after-proxmox-upgrade.118578/#post-518080?

Orkhan · Mar 27, 2023

leesteken said:
Maybe this post can help https://forum.proxmox.com/threads/vm-windows-cannot-start-with-ram-more-48gb.76617/post-340914? Try 59GB or 61GB.

Same problem.

Is this problem critical in any case? Can we just remove the memory from the hotplug and create a VM?

leesteken · Mar 27, 2023

Orkhan said:
Can you say it's critical problem? Maybe we simple turn of memory from HotPlug menu and use VM? Hm?

Orkhan said:
Is this problem critical in any case? Can we just remove the memory from the hotplug and create a VM?

I don't understand the question, sorry. For me, the problem is not critical because it's your problem. Maybe memory hotplug is critical for your use case? Only you can decide.

spirit · Mar 27, 2023

try to add

/etc/modprobe.d/vhost.conf
options vhost max_mem_regions=509

The main problem is that kvm have changed number of memory devices some year ago (to 64 if I remember).

and proxmox try to allocate with 256 dimm, up to 4TB, with an incremental dimm size (8 small dimm of 512M, then 8 small dimm of 1024M, then 8 dimm of 2048....).

this kvm option increase number of max dimm. (it's not enabled by default, because it can increase a little bit the latency)

A fix is coming soon, with a new maxmemory option and a fixed computed dimm size. (max=64GB , 64 dimm of 1G , max=128GB 64 dimm of 2G, ....)

emptness · May 30, 2023

Hello everybody!
Does anyone know? Have you already released a patch to fix this problem?

spirit · May 30, 2023

emptness said:
Hello everybody!
Does anyone know? Have you already released a patch to fix this problem?

not yet . I'm hoping that it'll be merge for coming proxmox 8.0.

are · Sep 27, 2023

Third post in this thread had *working solution* (for me):

https://forum.proxmox.com/threads/problem-with-hotplug-and-64gb-ram.73621/#post-329329

and later it was repeated

https://forum.proxmox.com/threads/problem-with-hotplug-and-64gb-ram.73621/page-2#post-544025

so

Bash:

# cat /etc/modprobe.d/modprobe.conf
options vhost max_mem_regions=512

(default is 64)

and reboot. Then just set 65536 for ram (wanted 64GB) or whatever else value you want.

The error message is misleading. Actual code checks more that simple alignment:

/usr/share/perl5/PVE/QemuServer/Memory.pm

Perl:

foreach_dimm($conf, $vmid, $memory, $sockets, sub {
            my ($conf, $vmid, $name, $dimm_size, $numanode, $current_size, $memory) = @_;

            my $mem_object = print_mem_object($conf, "mem-$name", $dimm_size);

            push @$cmd, "-object" , $mem_object;
            push @$cmd, "-device", "pc-dimm,id=$name,memdev=mem-$name,node=$numanode";

            die "memory size ($memory) must be aligned to $dimm_size for hotplugging\n"
                if $current_size > $memory;
        });

and for me current_size was end up being 66560

problem with hotplug and 64GB ram

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