problem with hotplug and 64GB ram
- Thread starter dz00te
- Start date
I am having the same issue and can't set more than 44GB of RAM.
Trying 65GB I get the error:
kvm: -device pc-dimm,id=dimm59,memdev=mem-dimm59,node=3: a used vhost backend has not enough free memory slots left
TASK ERROR: start failed: QEMU exited with code 1
(Running 8.3.0)
Trying 65GB I get the error:
kvm: -device pc-dimm,id=dimm59,memdev=mem-dimm59,node=3: a used vhost backend has not enough free memory slots left
TASK ERROR: start failed: QEMU exited with code 1
(Running 8.3.0)
you need to set max_mem_regions for the vhost module, e.g. like in https://forum.proxmox.com/threads/problem-with-hotplug-and-64gb-ram.73621/page-3#post-600504
I am still having this problem on PVE 8.3.2.
My max_mem_regions is set to 509 in vhost.conf. What should it be changed to?
I need hotplug and 64 GiB of memory. Is setting max_mem_regions the answer? I know 65 GB works, but I have 250+ VMs to create, so that jump from 64 GiB to 65 GiB means an additional 250 GiB of total memory. (not all on one host mind you.)
My max_mem_regions is set to 509 in vhost.conf. What should it be changed to?
I need hotplug and 64 GiB of memory. Is setting max_mem_regions the answer? I know 65 GB works, but I have 250+ VMs to create, so that jump from 64 GiB to 65 GiB means an additional 250 GiB of total memory. (not all on one host mind you.)
Seems like the error message could be improved on. Maybe with a suggestion of memory values to pick. The memory size input field has up and down arrows to increase or decrease the memory in 32 byte intervals. Can we make these arrows suggest working values?
Is there a chart or graph show the granularity changes per GB of memory? Or a formula?
Is there a chart or graph show the granularity changes per GB of memory? Or a formula?
it's not that easy/simple unfortunately 
https://git.proxmox.com/?p=qemu-ser...d31108705226b6e25f21318b5b1e2f1f;hb=HEAD#l185
https://git.proxmox.com/?p=qemu-ser...d31108705226b6e25f21318b5b1e2f1f;hb=HEAD#l185
Today I faced the same issue. I followed the setting here https://pve.proxmox.com/wiki/Hotplu...em_regions_when_hot-plugging_more_than_64_GiB
With hotplug enabled it seems impossible to set an even memory value after 48GB. Everytime memory is dividable thorugh 2GB after 48GB you get the error message. So it is indeed possible to set uneven values like: 49, 51, 53, 55 an so on...
With hotplug enabled it seems impossible to set an even memory value after 48GB. Everytime memory is dividable thorugh 2GB after 48GB you get the error message. So it is indeed possible to set uneven values like: 49, 51, 53, 55 an so on...
Don't rely on that "must be aligned to 2048 for hotplugging" - that message just lies and doesn't reflect what is being checked in the code.
There is a patch that calculates closes possible values and presents these in a error message (for some older proxmox version but should be easy do adapt):
https://bugzilla.proxmox.com/show_bug.cgi?id=3446
There is a patch that calculates closes possible values and presents these in a error message (for some older proxmox version but should be easy do adapt):
https://bugzilla.proxmox.com/show_bug.cgi?id=3446
Thanks for your reply.
As I wrote I can set uneven values (51GB, 53GB, ...) and successfully start the vm but with even values (50GB, 52GB, ...) and hotplug enabled vm cant be started and the error will appear. I was not referring to the message but in case actual behaviour.
The envirorment is on patch 9.1.6
As I wrote I can set uneven values (51GB, 53GB, ...) and successfully start the vm but with even values (50GB, 52GB, ...) and hotplug enabled vm cant be started and the error will appear. I was not referring to the message but in case actual behaviour.
The envirorment is on patch 9.1.6
It requires specific alignment values like described in comment 19 (https://bugzilla.proxmox.com/show_bug.cgi?id=3446#c19) and in rest of this bug report. Other values will fail to start.