[PVE-User] Hotplug Memory boots VM with 1GB

Wed Apr 15 17:40:51 CEST 2015

Alexandre --

Thanks for the response.  Yes, ACPI hotplug does work and is built into the
kernel in CentO 6.  ACPI hotplug has actually been supported since CentOS 5
as well.  I am able to hotplug disks, network, CPU and Memory once the
system is fully booted and ACPI does identify the event.  It just seems
that its a timing issue when proxmox tries to hotplug the memory I think
that Linux/ACPI isn't ready for it that early (at least for CentOS 6).
Hope this helps - let me know if I can gather any other information for
you.  We really weren't looking to move to CentOS 7 for a while since
CentOS 6 isn't EOL until 2020 and there is some reluctance in our group
around some of the changes in RHEL/Cent 7.

Thanks,
Brian

On Wed, Apr 15, 2015 at 1:27 AM, Alexandre DERUMIER <aderumier at odiso.com>
wrote:

> >>Yes, I do have the udev rules in place and when I increase the memory in
> the web gui from say 4GB to 4.5GB it will add all of the memory that it was
> missing from boot plus the additional 500. When I look in
> >>/sys/devices/system/memory it only lists the memory modules that were
> from when the system was on. I can also see in dmesg output "Hotplug Mem
> Device" from during boot but its almost like the kernel isn't getting
> notified >>during boot and which also keeps udev from ever seeing it and
> setting it to online. CentOS 6 should have no problem with hotplugging
> memory but it doesn't seem to take it with the way Proxmox handles it at
> boot.
>
> So,it's seem than acpi hotplug is not working.
> Can you hotplug virtio disk for example ?
>
> Also, I'm not sure that centos6 2.6.32 kernel have support for memory
> hotplug (maybe redhat has backported from 3.10 kernel, but I can't confirm)
>
>
> ----- Mail original -----
> De: "Brian Hart" <brianhart at ou.edu>
> À: "aderumier" <aderumier at odiso.com>
> Cc: "proxmoxve" <pve-user at pve.proxmox.com>
> Envoyé: Lundi 13 Avril 2015 04:36:43
> Objet: Re: [PVE-User] Hotplug Memory boots VM with 1GB
>
> Hi - Thanks for the response!
> Yes, I do have the udev rules in place and when I increase the memory in
> the web gui from say 4GB to 4.5GB it will add all of the memory that it was
> missing from boot plus the additional 500. When I look in
> /sys/devices/system/memory it only lists the memory modules that were from
> when the system was on. I can also see in dmesg output "Hotplug Mem Device"
> from during boot but its almost like the kernel isn't getting notified
> during boot and which also keeps udev from ever seeing it and setting it to
> online. CentOS 6 should have no problem with hotplugging memory but it
> doesn't seem to take it with the way Proxmox handles it at boot.
>
> Thanks!
>
> Brian
>
>
>
> On Sun, Apr 12, 2015 at 11:18 AM, Alexandre DERUMIER < aderumier at odiso.com
> > wrote:
>
>
> Hi,
>
> do you have the udev rules
>
> /lib/udev/rules.d/80-hotplug-cpu-mem.rules (not sure about centos path)
>
> SUBSYSTEM=="memory", ACTION=="add", TEST=="state", ATTR{state}=="offline",
> ATTR{state}="online"
>
>
> This is udev which enable the memory module after acpi hotplug.
>
> ----- Mail original -----
> De: "Brian Hart" < brianhart at ou.edu >
> À: "proxmoxve" < pve-user at pve.proxmox.com >
> Envoyé: Vendredi 10 Avril 2015 18:28:15
> Objet: Re: [PVE-User] Hotplug Memory boots VM with 1GB
>
> Hello All,
> I had some more time to play with memory hotplugging and was trying to
> make this work again. I noticed in the wiki it says it requires a kernel
> greater than 3.10. I was trying to get this to work with CentOS 6 systems
> as that is primarily what we are running and it is not on a 3.x kernel yet.
> However, Cent 6 does support hotplugging memory and CPU. I think the issue
> though is the memory is hotplugged at an an odd time that the VM isn't
> ready for it with CentOS 6. Once the system boots I still see 987MB of
> starting memory and if I increase the amount of memory through the proxmox
> GUI the VM immediately detects all of the memory it was supposed to have
> plus the additional memory I just added. I have also found that I can
> manually tell it to probe for memory by doing an "echo 0x100000000 >
> /sys/devices/system/memory/probe" and it will find one piece (you have to
> do this repeatedly for every module if it doesn't auto-detect the hotplug).
>
> Anybody have an idea of how to tell CentOS 6 to detect the hotplugged
> memory after boot? Also, I'm curious why the additional memory has to be
> hotplugged? When using VMware it doesn't do it in this way so how come
> KVM/QEMU does?
>
> Thanks,
>
> Brian
>
>
> On Sun, Mar 8, 2015 at 8:16 PM, Brian Hart < brianhart at ou.edu > wrote:
>
>
>
> Ah, you're absolutely right. It is in the wiki. I had skipped to the
> bottom part of the wiki that said "Memory Hotplug' and overlooked the part
> that referenced Linux guests specifically. It looks like it is probably
> udev rules I'm missing. I will look at adding that in and try again.
> Thank you for the follow up!
>
> Brian
>
>
>
> On Sun, Mar 8, 2015 at 12:16 PM, Alexandre DERUMIER < aderumier at odiso.com
> > wrote:
>
> BQ_BEGIN
> I have updated the wiki last month about memory && cpu hotplug
>
> https://pve.proxmox.com/wiki/Hotplug_%28qemu_disk,nic,cpu,memory%29
>
> ----- Mail original -----
> De: "Brian Hart" < brianhart at ou.edu >
> À: "proxmoxve" < pve-user at pve.proxmox.com >
> Envoyé: Samedi 7 Mars 2015 06:36:32
> Objet: [PVE-User] Hotplug Memory boots VM with 1GB
>
> Hello -
> I'm not sure if I'm running into a bug or if I'm missing something. I have
> done several tests playing with different settings for a VM and have found
> that consistently whenever I set Hotplug to allow memory it limits the
> guest VM to 1GB of memory even if I have more assigned to it at startup.
> Has anybody else seen this? Is there something special about the hotplug
> that this is expected that I'm not aware of?
>
> Thanks,
> Brian Hart
>
>
>
>
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