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Core Memory

Emte
over 6 years ago

Looking to start a discussion on Core memory usage and memory trouble-shooting in general

1) The first problem we are seeing is that the Core will often be at 0 free memory with a HUGE amount in standby. Yes I know low free memory is "normal" in current server OS's and that standby memory is available to be used by another application if it needs it. But that is certainly not my experience either and def not when RR is the one with all the memory in standby

I have a Core that has 125GB of memory, 25GB is in use from every process and 100GB is in standby. 0 Free

I see the TN below about write caching. But a few issues

https://support.quest.com/rapid-recovery/kb/119686/high-paged-pool-ram-utilization-on-systems-running-appassure-or-rapid-recovery

a) The Core is 2012 R2 so should not be having this issue.

b) The technote gives no indications of how to confirm if you are having this issue.

c) Without a way to confirm if I am having this issue, the technote may not even help

https://www.quest.com/community/products/rapid-recovery/f/forum/21016/core-memory-usage-in-hyper-v-vms-making-vms-unresponsive#

 

2) Rammap file summary will often show a HUGE amount (+100GB) of memory in standby

Is this normal, does it show a problem with write cache (or anything else)

Why does this memory only show up in RAMMAP file sumary and point to the dfs.records file of our repo.

What does it not show up as standby memory allocated to core.service.exe (or any process) in task manager/ resource monitor. This is not how process are supposed to act

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  • 0 over 6 years ago
    Hi Emte:

    For those who do not already know, the standby memory is memory containing cached data that Windows used already but believes that it may be necessary again.

    Standby Memory usage is fine as long as there are a few MBs of free physical memory (at least 3 to 5MB).

    If you do constantly have no Physical memory available then it is worth investigating. In most cases it means that there is more Standby memory added than released and the issue may be tracked to some peripherals (including storage and network adapters).

    The boring but proven way to address this is updating all available firmware and drivers. Once this is done, it may make sense to launch an app known to use a lot of memory and see how the system behaves. (Try with all the standby memory in use and then released).

    If you see an identifiable difference in performance, drop me a line and I will get you a command line tool for releasing the standby memory. In the Windows 2008R2 days I was scheduling it to run periodically.

    Since it would be nice to be able to trigger the cleanup when the Standby Memory size got to some pre-determined threshold, I tried to see if I can change anything in this 2012 app. Alas, since this was many workstations ago, I lost my notes re the code in this app. As such I tried to find some info on the web and interestingly enough I found this script in the TechNet Gallery that may be helpful in setting a size related trigger.

    gallery.technet.microsoft.com/.../c-PowerShell-wrapper-6465e028

    The issue with Rapid Recovery is that due to deduplication there are relatively few blocks reused so the standby memory is largely useless.

    Anyway, in my experience, back in the day when Windows 2008R2 ruled, some applications had a hard time loading when the Standby Memory was maxed out, in may cases because it was not released fast enough to accommodate the needs of the newly launched applications. I did not see this issue in windows 2012R2 and later.
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  • 0 over 6 years ago
    Hi Emte:

    For those who do not already know, the standby memory is memory containing cached data that Windows used already but believes that it may be necessary again.

    Standby Memory usage is fine as long as there are a few MBs of free physical memory (at least 3 to 5MB).

    If you do constantly have no Physical memory available then it is worth investigating. In most cases it means that there is more Standby memory added than released and the issue may be tracked to some peripherals (including storage and network adapters).

    The boring but proven way to address this is updating all available firmware and drivers. Once this is done, it may make sense to launch an app known to use a lot of memory and see how the system behaves. (Try with all the standby memory in use and then released).

    If you see an identifiable difference in performance, drop me a line and I will get you a command line tool for releasing the standby memory. In the Windows 2008R2 days I was scheduling it to run periodically.

    Since it would be nice to be able to trigger the cleanup when the Standby Memory size got to some pre-determined threshold, I tried to see if I can change anything in this 2012 app. Alas, since this was many workstations ago, I lost my notes re the code in this app. As such I tried to find some info on the web and interestingly enough I found this script in the TechNet Gallery that may be helpful in setting a size related trigger.

    gallery.technet.microsoft.com/.../c-PowerShell-wrapper-6465e028

    The issue with Rapid Recovery is that due to deduplication there are relatively few blocks reused so the standby memory is largely useless.

    Anyway, in my experience, back in the day when Windows 2008R2 ruled, some applications had a hard time loading when the Standby Memory was maxed out, in may cases because it was not released fast enough to accommodate the needs of the newly launched applications. I did not see this issue in windows 2012R2 and later.
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