Hyper-V Dynamic memory, Driver Locked

Hello All,
I've been wondering about the following.
I have 2 Dell R910 (Windows Server 2008R2 SP1) machines as my Hyper-V host machines, with around 40-50 VMs running on it. For most of my servers I've enabled dynamic memory, but on some of these machines I've seen the following:
For some reason this machine running Remote Desktop Services (with Web Access) is using around 3.8GB of memory.
Processes list only a fraction of the actual Memory being used.
But RAMmap shows that 2.5GB is being used by Kernel Drivers. From what I've read this might be the balooning effect of the dynamic memory. However, the RAM usage was the same yesterday evening (12h before I took these screenshots), when no one was actually
working on this server.
I've seen this happen on multiple of my guest machines, the machines are running Windows Server 2008 R2 SP1 Datacenter Edition.
Can anyone explain to me why it is doing this?
Thank you.
Kind Regards,
Tom

https://blogs.technet.com/b/vm/archive/2011/01/13/hyper-v-r2-service-pack-1.aspx
How does a virtual machine memory is taken ?
The
method of " balloon " - in the guest OS specific driver begins to consume the allocated memory , taking it to the OS in a VM could not refer to it , and in fact , giving the allocated memory hypervisor for other virtual machines.
The guest OS continues to believe that her "a lot" of memory, it just kind of busy process and marked as «driver
locked». When subsequent addenda to the memory of this virtual machine
will be added to the memory address space of the process - and released them for the needs of the OS.
Have a nice day !!!

Similar Messages

[2008 R2] Hyper-V Dynamic memory warning with half of vHost memory free

Our virtual server host system has about 19GB of Memory free (out of 32GB total), yet a virtual guest using Dynamic Memory was only being assigned 8GB and the demand was around 13GB, therefore generating a Warning state on the Memory Status. Logging onto
the guest machine showed about 8GB of memory being used as well. The end-users were receiving memory errors in their applications. Any idea why the guest system was in this warning state?

There is a perception in the OS. And different numbers come from different places.
In a nutshell, the RDP Server has a memory leak if you constantly disconnect and reconnect - and it ends up chewing up memory, but when available memory is tested this memory consumption is missed. If you logout of the RDP session instead of disconnecting
then the memory is given back and can actually be used.
It is a strange interaction with RDP that has been there since the original release. But it is specific to using RDP to connect to the Hyper-V Server for VM Management and disconnecting without ever logging out.
There was also a google process that many folks reported a long while back that caused memory consumption that prevented VMs from starting as well.
Brian Ehlert
http://ITProctology.blogspot.com
Learn. Apply. Repeat.
Disclaimer: Attempting change is of your own free will.

Hyper-V, Dynamic Memory, Memory Demand more than Maximum memory

Hi,
I have found that for some VMs Demand Memory more that Maximum Memory set.
Where can I found any documentation about this?

A VM can 'demand' more memory than is possible'
But it will never actually be given more then the maximum.
In the VM the application is asking for more RAM from the virtual memory manager of the OS in the VM (not to be confused with any memory management that the hypervisor is doing).
When the VM hits its Maximum setting it is no different than a physical machine hitting its physical RAM cap - the OS begins paging to give the application the additional RAM it is asking for.
It simply means that you have a greedy application. SQL and the Exchange mailbox role have a long history of being very greedy applications (SQL made many changes to work in concert with dynamic memory) - taking all of the RAM they could get.
In your case, you have a startup of 32GB a minimum of 24GB and a Maximum of 36GB. And the application in the VM would 'like' to have 54GB. If you look in your VM OS you will probably find that it is paging to disk.
What is your allocation setting? The default of 20% Higher?
Personally - I see little value in using dynamic memory with such a small window of difference between the startup, minimum, and maximum. It is as if you are trying to micro manage the feature, instead of allowing the feature to work as designed.
Dynamic memory is designed to balance RAM between all of the VMs on a particular hypervisor at the same time. And to allow use of all the RAM the machine has, if there is a workload that can use it. If the VM wants 64GB, why not give it that.
Dynamic memory will not starve other VMs to give this VM more RAM (unless you give this VM a higher priority). But it will take RAM away from a VM (if absolutely necessary) to allow another VM to meet its requirements.
Any VM is always guaranteed its startup, at boot time. And dynamic memory will not starve it below it minimum - and if the VM is not using RAM it will take RAM away down to the minimum. And a VM will never be given more than the maximum, even
if the VM wants more.
Brian Ehlert
http://ITProctology.blogspot.com
Learn. Apply. Repeat.
Disclaimer: Attempting change is of your own free will.

Hyper-V Dynamic Memory Demand Blank

Hi,
im wondering about a blank Memory demand Value at a virtual machine on my Windows 8.1 with enabled Hyper-V Feature. Inside the VM the OS is Hyper-V Server 2012 R2. I tried to update the Integration Services but they are actual already. Here is screenshot
of the Memory Monitoring i get in the Hyper-V Console:
Can you help me guys?
Thanks
Michael

Hi mknuel,
For troubleshooting , I would suggest you to copy the VHD file of 2012R2 VM then create a new VM and attach the VHD file to see if it works .
Also , please keep the host and VM up-to-date .
Best Regards
Elton Ji
We
are trying to better understand customer views on social support experience, so your participation in this
interview project would be greatly appreciated if you have time.
Thanks for helping make community forums a great place.

Dynamic memory allocation failure

Dear reader,
We sometimes have a problem where our windows 2012 r2 RDS virtual servers, that reside on windows 2012r2 hyper-v hosts, loose their dynamic memory and only have their startup memory left to work with. Users start complaining that things are very slow etc.
If I check several screens (RDS Broker load balancing, hyper-v manager, cluster manager and the vm's task manager) it's clear that the vm only has its startup memory allocated. I'm not sure if this happens instantly or immidiatly after the nightly reboot.
To resolve the problem we have to call all users on the vm where it happens and ask them to logoff (if they are even able to), and then we reboot the machine.
I have checked the logs from the machine where the VM resides on and the logs from the vm itself. But I cannot find anything. We also have alot of windows 2008r2 vm's with dynamivc memory, but none of those have ever had this problem.
Searched the internet, but so far it seems we are only.
Can anyone give me a lead to troubleshoot this?
Best regards,
Ruud Boersma
MCITP Enterprise administrator

Hi all,
I'm going to be "one of those people" who revives dead posts for something that is relevant but obviously not fixed... sorry in advance!
We have the exact same situation, a bunch of RDSH guests with Dynamic memory turned on (60+ of them). every day between 1-8 of them will fail to allocate Dynamic memory and will be stuck on their startup RAM amount. This really hurts our users at peak
times.
I have engaged our TAM and have raised a case with PSS, Usual story "your the only one with this problem". Which obviously isn't true.
So, we have tons of free RAM on the hosts, 600GB+ on most of them, the issue affects RDSH hosts at random, across multiple hosts and clusters.
The screen shots attached are of one of our hosts from this morning. it has 8GB startup, 8GB minimum, 32GB Maximum RAM configured, with a 23% buffer. the host has 752GB RAM FREE. Notice how the perf counter "Hyper-V Dynamic Memory Integration Service"
is reporting "0", it should be reporting "32768". also under task manager on the VM we are missing "Maximum memory" which should be just below "Hardware reserved" in the bottom right hand corner.
Looks like the balloon driver is being delayed at boot time, we are going to XPerf all the servers in the hope that we can catch the critter. It's an unusual problem.
We only have Acrobat PDF viewer, word viewer, excel viewer and two custom dot.NET applications installed on the guests. Some of the servers are also just dumb RDSH hosts, with not connection broker configured, using an F5 loadbalancer for load distribution
and session management. All guests are 2012R2 patched up to March 2015, integration Services are installed and up to date (its an enlightened OS remember).

SQL Server 2012 Dynamic Memory

Does anyone know if Dynamic memory can be used for SQL 2012 on a Hyper-V 2012 VM?
There seems to be conflicting views of this, some say only static memory can be used or performance would be affected?

Hi,
Q7: Is Hyper-V Dynamic Memory supported for SQL Server?
A7: Hyper-V Dynamic Memory is fully supported with SQL Server. Only SQL Server versions and editions that support Hot Add Memory (Enterprise and Datacenter) can see memory that is added by using Hyper-V Dynamic Memory. SQL Server 2012
Standard edition also recognizes Hot Add memory when running in a virtual enviroment. SQL Server versions that do not support Hot Add Memory are still supported. But these versions will detect only the memory that is present in the operating system when
SQL Server starts. Before you deploy Hyper-V Dynamic Memory, please read the following resources when you use Hyper-V Dynamic Memory with SQL Server:
http://support.microsoft.com/kb/956893
http://OpsMgr.ru/

VM with dynamic Memory in Bootloop

Hey there,
in a Server 2012 Cluster there is a VM with Server 2003 Ent. SP2 x86 with dynamic Memory which hangs in a bootloop. There is no Bluescreen or something like this. Change it to static memory, everything is fine.
tried:
- reinstalled the Integration Services
- exported and imported the VM
- installed older integration services
no changes to the behavior of the VM in startprocess.
Can anyone help with a solution?
Thanks!

Hi,
Thanks for your posting. I did some test in my lab but I can’t reproduce your issue, so this is not a generic issue.
Where this VM come from, migrated from Windows Server 2008 R2 cluster or new installed?
Is this issue happen on other Windows Server 2003 guest VM?
Do you have other Windows Server 2012 Hyper- V host server, I mean a standalone server, not the cluster node. You may import the VM to a standalone server to check whether it has some issue.
On the Windows Server 2012 Hyper-V host server which runs the VM, check event viewer, find related error logs and post them for further troubleshooting.
For more information please refer to following MS articles:
Hyper-V Dynamic Memory Overview
http://technet.microsoft.com/en-us/library/hh831766.aspx
What's New in Hyper-V
http://technet.microsoft.com/en-us/library/hh831410.aspx
Hyper-V Dynamic Memory Configuration Guide
http://technet.microsoft.com/en-us/library/ff817651(v=WS.10).aspx
Hope this helps!
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High Memory consumed when Dynamic memory is Enabled in Hyper-V Machine

I have created a VM using Hyper-V with Enabling Dynamic Memory option on a 2012R2 server machine.
After creating the VM I see that the memory consumption of the VM machine as 85%.
Would like to know if any efficient way to use "Enable Dynamic Memory" option while configuring the VM so that the memory consumption will be reduced.

As others have said it depends on the application being used. Also how do you have your guests configured with Startup memory, minimum memory and maximum memory? If your application is poorly written and has a memory leak, you will see dynamic memory just
grow. If the application is just heavy because of traffic or caching it will use lots of memory.
Example for me is a web application that is proprietary. during no usage it might be using roughly 400 MB on the server, but then when it gets used it will grow. I've seen some webservers hit 10 GB as for other ones grow maybe to a meg. After things calm
down a bit I notice memory returns back down to a 400 MB to 700 MB level. That is just how my application is and how i serve it up to customers. I had to track all that stuff prior. You can use Microsoft MAP to help with your dynamic memory settings.
For SQL server it can be done as well, but as Darren said before you might not want to do it. In my environment i do it, but I have tweaked things to work for me. Example is tweaking database memory usage to match startup memory OS it appears static, but
then leaving dynamic for processes that fire outside of SQL server. Here is a
guide for SQL server and dynamic memory.

Hyper-V 2012 R2 - live migration dynamic memory issue

Hi..
we use a two node hyper-v cluster.
On each node running 5 vm that shared the 64GB system memory.
The vms are configured to use dynamic memory. The sum of the startup (min) memory of the 10 vms are currently 50 GB.
So now our problem:
If we try to drain roles on node A for maintenance purpose two vms are still on node A because they wasted currently each 25GB memory and so on node B is not enough free memory to host this vms.
That sounds logical
But as all vms configured to use dynamic memory they should shrink their memory to get enough space for all vms? If we shutdown all vms, move it to one node, then everything works fine.
Is it by design that live migration do not trigger the vm to shrink their memory?
Best regards, Alexander Zirbes

Hi Alexander,
Dynamic memory means that memory can increase or decrease based on the demand of the VM, not based on the load of the Hyper-V host. If the gust OS of VM dont need that much memory, memory will be released. I dont think live migration has any role shrinking
the allocated memory of a VM.
Since you are using two node cluster, you should only load 50% resourses on each host so that incase of a failure of second node, the first node can have all the VMs.
This calculation will become more effective if you have more nodes. I am having a six node cluster and I load each host upto 80% so that in case of a single node failure, the VMs can be split on other five nodes without issues.
Cheers,
Shaba
Optimism is the faith that leads to achievement. Nothing can be done without hope and confidence.
InsideVirtualization.com

Dynamic Memory and Data Deduplication

Hi,
I'm currently testing W2K12 Deduplication feature on some servers, and I was wondering if I could enable "Dynamic Memory" on the VM in Hyper-V? Because the job only uses percentage of memory for the dedup job, I guess it's not possible.
Thanks in advance!

I know it old thread, but I ran into this and could not find anything on it but here, so I am adding my experience.
I can concur with 3magroup...
In my environment Windows Server 2012 with Dynamic Memory and Deduplication enabled, the HyperV does not release the driver locked ram for the dedup optimization. What resulted was an insane amount of paging and a painfully slow VM. Increasing the memory
buffer for the dynamic memory did not cause the HyperV to release the memory for the dedup. Instead, it still "driver locked" nearly all of the ram, which did not make sense to me based on my understanding of the Memory Buffer setting.
I can verify the VM poor performance and dedup using the paging file with the Resource Monitor, disk section, and the Driver locked RAM with RamMap.

Dynamic memory not released to host

Dear Techies,
Ours is a small Hyper V virtual server infrastructure with three DELL power-edge physical hosts(Windows server 2012 Datacenter) and around 15 virtual machines running on top of it. The hosts are added to fail-over cluster. Each host has 95 GB RAM. All the
VMs are running Windows server 2012 standard edition.
We have installed terminal services(TS licensing, TS connection broker, TS session host) in four VMs with the following dynamic memory settings:
Start-up RAM : 2048 MB
Minimum RAM : 2048 MB
Maximum RAM : 8192 MB
Below mentioned applications are configured in the server:
Nova Application Installed
SQL Developer Tool is Configured (ODBC Connection established for Database communication)
FTPs communication allowed for File Transfer
McAfee Agent is configured (Virus Scanner)
Nimsoft Robot Agent Configured – Monitoring
Terminal Service
Enabled Multiple terminal sessions based on customer requirement
BGinfo tool configured through group policy for customized desktop background
The average memory utilization in the terminal servers are 3.6 GB. As per dynamic allocation the maximum RAM requirement/allocation till date is 4GB. As seen in Hyper V console, the current RAM demand is 2300 MB and assigned memory is 2800 MB.
However, the earlier assigned RAM in the server is ballooned/faked to the VM as driver locked memory. This is by design. Despite the memory being released back to the host, the server still shows up the 4Gb which makes the memory utilization report from
monitoring tools look 80% (3.2 GB out of 4 GB).
As a result, the memory utilization report is always based on the current dynamically allocated RAM and not calculated based on the maximum assigned RAM(8GB in this case). To make it clear: If the
currently assigned RAM is 4Gb and utilization is 3.2 GB the utilization % is reported as 80%. However, if calculated in accordance with maximum RAM capacity of the server it would be 40% ((3.2/8)*100).
Is there any way to release the driver locked memory from the VM.?
Regards,
Auditya N

I am not really clear on the point of your question.
Allocated RAM is what is currently in use / allocated to a VM out of the physical RAM pool. It is Demand + Buffer. The demand is based on the applications in the VM and what they think they need and how efficiently they return unused memory
to the machine. This has nothing to do with in-application paging (which happens a lot with Terminal Servers).
So yes, the memory utilization is accurate in relation to physical RAM utilization.
Dynamic Memory is about efficiency, not about over-allocation. Hyper-V can never give VMs more RAM than is in the physical RAM pool. The VMs can be configured to have more RAM than is in the physical RAM pool - but the VMs will hit the top of
the pool and not be allowed to have any more. There is no ballooning or paging to disk.
So, you maximum allocated could go beyond what is possible. But that would mean that your utilization would be artificially low if this was used in the calculation.
Brian Ehlert
http://ITProctology.blogspot.com
Learn. Apply. Repeat.

Dynamic Memory on Linux VM

Hello!
Hyper-V 3.0 is great! After it will be released, I think it will become the most popular hypervisor. But it remains a major drawback.
Nowhere announced support for dynamic memory for Linux VM on Hyper-V.
Planned at least in some perspective to implement this functionality?
Now we have to use two different hypervisors, as Hyper-V does not meet all the requirements of our customers.
Mark Tepterev
Oversun

~
~
Moved P.P.P.S.
Q from Brian Wong:
----- Original Message -----
From: "Brian Wong"
To: <[email protected]>
Sent: Thursday, March 06, 2014 9:24 AM
Subject: Re: Linux does not use more than the startup RAM under Hyper-V with dynamic memory enabled
On 3/6/2014 1:20 AM, Brian Wong wrote:
> The kernel is built with the full set of Hyper-V drivers, including the
> key "Microsoft Hyper-V Balloon Driver" as well as memory hot-add and
> hot-remove functionality. This is happening with both the Gentoo-patched
> 3.10.32 kernel and the vanilla 3.12.5 kernel. The host machine has a
> total of 24 GB of memory.
>
> For now, I am working around the issue by starting the VM with the
> startup memory set to the maximum and letting Hyper-V take the usused
> memory back when it is not in use. The VM will then get the extra memory
> when it needs it.
>
> Have I encountered a bug in the Hyper-V balloon driver?
>
Just a correction: the vanilla kernel version is 3.13.5, not 3.12.5.
Sorry for any confusion.
Brian Wong
http://www.fierydragonlord.com
----- Original Message -----
From: "Brian Wong"
To: <[email protected]>
Sent: Thursday, March 06, 2014 9:20 AM
Subject: Linux does not use more than the startup RAM under Hyper-V with dynamic memory enabled
I'm new to LKML, so please don't be too hard on me :)
I'm running Gentoo Linux under Microsoft Client Hyper-V on Windows 8.1
Pro, and I've noticed some odd behavior with respect to dynamic memory
(aka memory ballooning). The system will never use more than the startup
memory defined in the virtual machine's settings.
( VVM: typewriting error viRtual fixed by me, for best search in future )
For example, if I set the startup memory to 512 MB, and enable dynamic
memory with a minimum of 512 MB and a maximum of 8192 MB, the system
will never allocate than 512 MB of physical memory, despite Hyper-V
assigning more memory to the VM and the added memory being visible in
the output of "free" and "htop". Attempting to use more memory causes
the system to start paging to swap, rather than actually allocating the
memory above the startup memory assigned to the VM.
The kernel is built with the full set of Hyper-V drivers, including the
key "Microsoft Hyper-V Balloon Driver" as well as memory hot-add and
hot-remove functionality. This is happening with both the Gentoo-patched
3.10.32 kernel and the vanilla 3.12.5 kernel. The host machine has a
total of 24 GB of memory.
Brian Wong wrote On 3/6/2014 1:20 AM:
Just a correction: the vanilla kernel version is 3.13.5, not 3.12.5. )
For now, I am working around the issue by starting the VM with the
startup memory set to the maximum and letting Hyper-V take the usused
memory back when it is not in use. The VM will then get the extra memory
when it needs it.
Have I encountered a bug in the Hyper-V balloon driver?
Brian Wong
http://www.fierydragonlord.com
----- Original Message -----
From: "Victor Miasnikov"
To: [email protected]; "Brian Wong"
Cc: "Abhishek Gupta (LIS)" ( zzzzzzzzzzzzzzz (at) microsoft.com>; "KY Srinivasan" zzzzzzzzzzz (at) microsoft.com
Sent: Thursday, March 06, 2014 1:07 PM
Subject: Re: Linux does not use more than the startup RAM under Hyper-V with dynamic memory enabled RE: [PATCH 2/2]
Drivers: hv: balloon: Online the hot-added memory "in context" Re: [PATCH 1/1] Drivers: hv:
Hi!
Short:
Question to Linux kernel team:
may be patch
>>> [PATCH 2/2] Drivers: hv: balloon: Online the hot-added memory "in context"
can solve problems with dynamic memory hot add in Hyper-V VMs with Linux OS ?
Full:
BW>> .., if I set the startup memory to 512 MB, and enable dynamic
BW>> memory with a minimum of 512 MB and a maximum of 8192 MB,
BW>> the system will never allocate than 512 MB of physical memory
BW>>
BW>> Have I encountered a bug in the Hyper-V balloon driver?
BW>>
Unfortunately, It's long story . . . :-(
a)
I already ( on January 09, 2014 2:18 PM ) write about problems with "Online the hot-added memory" in "user space" see
P.P.S.
b)
See
Bug 979257 -[Hyper-V][RHEL6.5][RFE]in-kernel online support for memory hot-add
https://bugzilla.redhat.com/show_bug.cgi?id=979257
( Info from this topic may be interessant not only for RedHat users )
b2)
Detail about pathes related problem "Online the hot-added memory" in "user space" :
>>> [PATCH 2/2] Drivers: hv: balloon: Online the hot-added memory "in context"
>>>
>>>
>>> === 0001-Drivers-base-memory-Export-functionality-for-in-kern.patch
>>> . . .
>>> +/*
>>> + * Given the start pfn of a memory block; bring the memory
>>> + * block online. This API would be useful for drivers that may
>>> + * want to bring "online" the memory that has been hot-added.
>>> + */
>>> +
>>> +int online_memory_block(unsigned long start_pfn) { struct mem_section
>>> +*cur_section; struct memory_block *cur_memory_block;
>>>
>>> . . .
>>> ===
>>>
>>>
>>> ==
>>> . . .
>>> == 0002-Drivers-hv-balloon-Online-the-hot-added-memory-in-co.patch
>>>   . . .
>>>    /*
>>> -   * Wait for the memory block to be onlined.
>>> -   * Since the hot add has succeeded, it is ok to
>>> -   * proceed even if the pages in the hot added region
>>> -   * have not been "onlined" within the allowed time.
>>> +   * Before proceeding to hot add the next segment,
>>> +   * online the segment that has been hot added.
>>>     */
>>> - wait_for_completion_timeout(&dm_device.ol_waitevent, 5*HZ);
>>> + online_memory_block(start_pfn);
>>>
>>>   }
c)
Before apply patches ( see in P.S. about native udev-script) we are need use one of this methods:
[ VVM:   URL of this topic skipped ]
c1)
"/bin/cp method" by Nikolay Pushkarev :
Following udev rule works slightly faster for me (assuming that memory0 bank always in online state):
SUBSYSTEM=="memory", ACTION=="add", DEVPATH=="/devices/system/memory/memory[1-9]*",
RUN+="/bin/cp /sys$devpath/../memory0/state /sys$devpath/state"}}
( VVM : of course all need be place in one line, 2 line in this msg. -- only for good visual formating reasons )
c2)
udev rule using "putarg" by Nikolay Pushkarev :
Even "/bin/cp method" udev rule work time to time not as need :-(
As a result, Nikolay Pushkarev write a program putarg.c, that is even faster than "/bin/cp method" :
==
#include <stdio.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <string.h>
int main(int argc, char** argv) {
int i, fd;
if (argc < 2) return 0;
if ((fd = open(argv[1], O_RDWR)) < 0) return 1;
for (i = 2; i < argc; i++) {
    if (write(fd, argv[i], strlen(argv[i])) < 0) {
      close(fd);
      return i;
close(fd);
return 0;
==
The first argument - the name of the output file ,
and argument number 2 ( and all subsequent ( if exist ) ) - are text that are wiil be written in output file.
Compile source code to executable file by run command:
gcc -o putarg -s putarg.c
The resulting binary need be placed an accessible location , such as /usr/bin, or wherever you want.
Now udev rule using "putarg" can be written as :
SUBSYSTEM=="memory", ACTION=="add", RUN+="/usr/bin/putarg /sys$devpath/state online"
This complex solutions ( compiled file and udev-rule ) works exceptionally fast.
Best regards, Victor Miasnikov
Blog: http://vvm.blog.tut.by/
P.S.
Nikolay Pushkarev about standart udev-script :
Strange, that the native udev-script
SUBSYSTEM=="memory", ACTION=="add", ATTR{state}="online"
triggered somehow through time ( VVM: very often not work as need )
P.P.S.
----- Original Message -----
From: "Victor Miasnikov"
To: "Dan Carpenter"; "K. Y. Srinivasan" ; <[email protected]>
Cc: "Greg KH" ; <[email protected]>; <olaf (at) aepfle.de>; ""Andy Whitcroft"" <zzzzzzzzzzzz (at)
canonical.com>;
<jasowang (at) redhat.com>
Sent: Thursday, January 09, 2014 2:18 PM
Subject: RE: [PATCH 2/2] Drivers: hv: balloon: Online the hot-added memory "in context" Re: [PATCH 1/1] Drivers: hv:
Implement the file copy service
Hi!
> Is there no way we could implement file copying in user space?
For "file copy service" "user space" may be pretty good
But I ( and other Hyper-V sysadmin) see non-Ok ( in "political correct" terminalogy) results with "hv: balloon: Online
the hot-added memory" in "user space"
==
[PATCH 2/2] Drivers: hv: balloon: Online the hot-added memory "in context"
==
What news? Roadmap?
Best regards, Victor Miasnikov
Blog: http://vvm.blog.tut.by/
~
~
~
~
~
~
~
~
~
----- Original Message -----
From: "KY Srinivasan"
To: "Victor Miasnikov"; [email protected]; "Brian Wong"
Cc: "Abhishek Gupta (LIS)"
Sent: Thursday, March 06, 2014 1:23 PM
Subject: RE: Linux does not use more than the startup RAM under Hyper-V with dynamic memory enabled RE: [PATCH 2/2]
Drivers: hv: balloon: Online the hot-added memory "in context" Re: [PATCH 1/1] Drivers: hv:
> -----Original Message-----
> From: Victor Miasnikov
> Sent: Thursday, March 6, 2014 3:38 PM
> To: [email protected]; Brian Wong
> Cc: Abhishek Gupta (LIS); KY Srinivasan
> Subject: Re: Linux does not use more than the startup RAM under Hyper-V
> with dynamic memory enabled RE: [PATCH 2/2] Drivers: hv: balloon: Online
> the hot-added memory "in context" Re: [PATCH 1/1] Drivers: hv:
>
Victor,
I will try to get my in-context onlining patches accepted upstream.
K. Y

Guest keeps on consuming all the dynamic memory

Software:
Host: Windows Server 2012 R2 x64 fully patched
Guest: Windows 8 Update 1 x64 (Fully Patched).
I've been experience this problem for a few months and really don't know where to go from here. After starting the specific guest that is having the issue it will happen anywhere between 3-7 days. The guest will consume almost all the memory. The only way
i can log into the guest is with hyper-v manager. Remote Desktop will hang. Then when i log into the guest i can't bring up task manager or many things. Every time i have to kill the vm and restart it. Last time i thought to keep process monitor up and
running so i could inspect things. Well it happened today again. According the hyper-v manager the guest was consuming almost 24GB of memory:
here is the memory demand:
What's wierd is when i logged into the vm it was showing it only had 4GB of memory with 3.1GB used. There was hardly anything running other than a few services and they weren't using much memory. Quickly process explorer locked up on me. After logging in
for say 5-10 minutes this always happens too. After trying to diagnose the for a few minutes it will appear i have rebooted the system because i will get the following:
but i definitly did not reboot. If i come back in 24 hours it will still be at the same spot. Again i have to kill the vm but the same vicious cycle will ensue. I'm at a loss how to diagnose this. I've tried to scour the event viewer but it hasn't helped.
Sure i could just turn dynamic memory off or lower the upper threshold of the dynamic memory but i shouldn't have to do that. Thats really just masking the problem. The only default value of dynamic memory i changed was the "Startup Memory". I really
don't want to rebuild the vm but what other options do i have here?

Well i updated one of my main programs on that machine (the on that i would think used "Most" of the memory) and i "thought" it went away but nope i was wrong. It came back. Luckily i left rammap & process explorer running. I could
it when it was consuming almost 6GB rather than the 20+ GB like before. Here is a screenshot of rammap:
As you can see "Paged Pool" memory is huge. I closed almost every app running on the system hoping that would help but it really didn't. The only thing that is running at this point outside of the normal windows processes is EMET 5 & Nortan
Antivirus. I tried to stop halt "Auto Protect" & the firewall but that didn't help any.
unfortunately, though i did catch it early, most programs will fail to load. Even file explorer fails to load. As usual after interacting with process explorer for awhile i get the white screen of death out of it. Hmmmm figure out why so much pool memory
is being consumed.

Dynamic memory freezes

Hi guys,
we are using three node cluster with Windows Server 2012R2. Our virtual machines are virtual
desktops with Windows 8.1 guest OS, 4 vCPU and 8 GB of dynamic memory.
Sometimes dynamic memory stops working, guest OS is not able to allocate more RAM and starts to swap. This swapping slows performance of all our virtual machines, since
all virtual machines are on same cluster shared volume. This happens at random RAM amount allocated, for example at 2.6 GB,
which is way below our 8 GB limit.
Live migration helps to solve this issue for migrated VM, after live migration the guest OS is able to allocate
more ram and starts to work properly, swapping disappears. However after some time, problem appears on other VM.
Our physical machines have 2x 10core Xeon and 394 GB of RAM. Only about 30% of RAM is used, so there is free space for all virtual machines. But we need to solve this issue so dynamic RAM starts to work properly.
Do you have similar experience?

Hi manasj,
Please check event log "Microsoft-Windows-Hyper-V Worker/Admin " to see if there is any clue .
Also please refer to the following potetial cause :
" In a Hyper-V Failover Cluster, a virtual machine can have its configuration information stored on cluster shared storage (a Physical disk resource or a Cluster Shared Volume (CSV). If the physical disk resource or the Cluster Shared Volume (CSV) goes Offline or Fails,
the VM placed in a critical state. Once the storage is re-connected, the VM should no longer be in a critical state. However, virtual machine worker process (vmwp.exe) does not refresh all of its file handles."
For details please refer to following link :
http://support.microsoft.com/kb/2504962/en-us
Best Regards
Elton Ji
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Dynamic Memory in the production environment

Hi,
We configure all production VMs with static memory on Hyper-v 2012
we need to make sure there is no negative impact on VM performance if we use Dynamic memory , as we read for 2 years
not recommend to use dynamic memory in the production.
I preferred the answer with Trusted URL
Ramy

Hiya,
The best answer you can get is, that it is dependent on the application running on the server O/S.
The reason that dynamic memory is not recommended for production environments, is that many applications are not supporting it. That is usually seen on memory intensive applications(SQL is an example) or simply because of caching types of functions. (SharePoint
is an example).
The major concern here is when VM's are decreasing the memory for a VM, the application does not understand this. Usually it is not a problem when increasing the memory. - Again it will depend on the application.
Think of it as hot swap memory and how you used to use that in the physical machine days.
Also when there is not adequate memory, operating system will use paging. Paging uses disks and disks has a lower access time than memory.
In general dynamic memory is easier to control than dynamically expanding disks, as you can set the buffer size of the memory, which is still not available for the dynamic disks.
Besides the above, the following links states:
"Workloads that are not NUMA-aware will not take advantage of virtual NUMA. However, the guest operating system may perform some NUMA optimization. Enabling Dynamic Memory (therefore presenting only a single virtual NUMA) should not cause performance
degradation"
http://technet.microsoft.com/en-us/library/dn282282.aspx

Hyper-V Dynamic memory, Driver Locked

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