Hi, We have a fileserver that SQL backups are backed up to every night over the network. During these backups, Physical Memory goes to 99% use on the backup server. The server is very very slow during this time. On the process view of Task Manager, no processes are taking very much memory. I see that a lot is cached, but it is always like this even when backups are not going on and there is a lot more available physical memory. How can I find out what is going on? Thanks.

Hi, Please check if the solution in the following KB articles helps: The system performance of the server becomes severely decreased when you try to copy files from a server that is running Windows Vista or Windows Server 2008 through a network http://support.microsoft.com/default.aspx?scid=kb;EN-US;971442 You experience performance issues in applications and services when the system file cache consumes most of the physical RAM http://support.microsoft.com/default.aspx?scid=kb;EN-US;976618 In addition, you can refer to the following blog for more information about cache: http://blogs.msdn.com/b/ntdebugging/archive/2007/11/27/too-much-cache.aspx Hope it helps.This posting is provided "AS IS" with no warranties, and confers no rights. Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hi Joson, Thank you for your response. In regards to: http://support.microsoft.com/default.aspx?scid=kb;EN-US;971442 I cannot tell if this article is referring to the server that it is copying to, or the server that it is copying from? Our fileserver that expereincies this memeory issue is only having files copied to it. It looks like the hotfix only applies to servers that are having files copied from them, unless I am misunderstanding it. Please advise. Thanks!

Hi, Check the following when the system is in the problem state: Open perfmon and select system monitor Click on the add (+) icon on the toobar Expand the memory object and select "System cache resident bytes " counter, click add and close the "System cache resident bytes" counter should now be in the list below select this counter and check the max value above, this number is in bytes, convert it into megs and check how much memory its taking This is the system cache working set. When there are lots of cached IOs happening on the server, this counter might grow, as the limit of system cache on a x64 system is 1 TB, it can consume the entire amount of RAM, to limit the system cache we can use the Dynamic Cache service; as mentioned previously by Joson. This service should not be used on 2008 R2 servers. http://support.microsoft.com/default.aspx?scid=kb;EN-US;976618 how much RAM does the server have? Please find below the Dynamic Cache configuration steps: Dynamic Cache configuration steps: ======================= Download Dynamic Cache utility http://www.microsoft.com/downloads/details.aspx?FamilyID=e24ade0a-5efe-43c8-b9c3-5d0ecb2f39af Extract it to a folder Copy the DynCache.exe and DynCache.pdb files from “Retail\AMD64” folder to C:\windows\system32 From a command prompt, run: > SC create DynCache binpath= %SystemRoot%\System32\DynCache.exe start= auto type= own DisplayName= "Dynamic Cache Service” Double click the “DynCache.reg ” registry file in the extracted folder. This registry file contains default settings and should be modified. Registry Configuration Important: You should always take a backup before making any changes in the registry The Dynamic Cache Service will monitor the registry for configuration changes. You do not need to restart the service if you change any of these registry settings. Open Regedit.exe and go to this registry location and make the changes. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DynCache\Parameters RegValue: MaxSystemCacheMBytes Type: REG_DWORD Values: 2048 (decimal) ----> this value is customizable and can be increased or decreased based on the amount of RAM on the system. Close the registry Go to Start > Run > Services.msc and Start the “Dynamic Cache” service. The dynamic cache configuration does not require a reboot Please let me know if you have any questions. Thanks, Madhurjya

Hi, Thanks for your clarification. In this case, the hotfix does not apply to this issue. Thanks.This posting is provided "AS IS" with no warranties, and confers no rights. Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hi, Any update on the issue? Please do not hesitate to respond back, if you need further assistance. Thanks.This posting is provided "AS IS" with no warranties, and confers no rights. Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hi, Check the following when the system is in the problem state: Open perfmon and select system monitor Click on the add (+) icon on the toobar Expand the memory object and select "System cache resident bytes " counter, click add and close the "System cache resident bytes" counter should now be in the list below select this counter and check the max value above, this number is in bytes, convert it into megs and check how much memory its taking This is the system cache working set. When there are lots of cached IOs happening on the server, this counter might grow, as the limit of system cache on a x64 system is 1 TB, it can consume the entire amount of RAM, to limit the system cache we can use the Dynamic Cache service; as mentioned previously by Joson. This service should not be used on 2008 R2 servers. http://support.microsoft.com/default.aspx?scid=kb;EN-US;976618 how much RAM does the server have? Please find below the Dynamic Cache configuration steps: Dynamic Cache configuration steps: ======================= Download Dynamic Cache utility http://www.microsoft.com/downloads/details.aspx?FamilyID=e24ade0a-5efe-43c8-b9c3-5d0ecb2f39af Extract it to a folder Copy the DynCache.exe and DynCache.pdb files from “Retail\AMD64” folder to C:\windows\system32 From a command prompt, run: > SC create DynCache binpath= %SystemRoot%\System32\DynCache.exe start= auto type= own DisplayName= "Dynamic Cache Service” Double click the “DynCache.reg ” registry file in the extracted folder. This registry file contains default settings and should be modified. Registry Configuration Important: You should always take a backup before making any changes in the registry The Dynamic Cache Service will monitor the registry for configuration changes. You do not need to restart the service if you change any of these registry settings. Open Regedit.exe and go to this registry location and make the changes. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DynCache\Parameters RegValue: MaxSystemCacheMBytes Type: REG_DWORD Values: 2048 (decimal) ----> this value is customizable and can be increased or decreased based on the amount of RAM on the system. Close the registry Go to Start > Run > Services.msc and Start the “Dynamic Cache” service. The dynamic cache configuration does not require a reboot Please let me know if you have any questions. Thanks, Madhurjya I will be capturing some counters tonight, and will report back with my findings.

It looks like the max System Cache Resident is about 7458mb. There is 8GB of memory on the server. With this in mind, where should I set the Dynamic Cache?

Should I limit it to 7GB?

Hi, It is difficult to tell what to set the System File Cache's working set size to. A high cache working set size is good for file servers, but bad for large memory application and a low working set size could hurt everyone's I/O. I am afraid that you need to perform some testing to determine what is the best for the server. For more information, please see http://blogs.msdn.com/b/ntdebugging/archive/2009/02/06/microsoft-windows-dynamic-cache-service.aspx Thanks.This posting is provided "AS IS" with no warranties, and confers no rights. Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

This service does not appear to be helping in our situation. I have the system cache limited to 90% physical ram, yet during file transfers, we still over near 100% physical memory. I have now changed the registry to limit the cache size to 80% and will see if that helps. I left all other settings at default. According to the documentation, there is nothing else to it.

I guess a better question would be, what is the best way I can see that the service is working properly?

I changed MaxSystemCacheMBytes to 80 (which as I understand is limiting system cache from taking no more than 80% of physical ram). However, I noticed that physical memory never went above 25% usage! Previoulsy it was hitting 100% at the MaxSystemCacheMbytes setting. What am I doing wrong? So now it seems that it is not taking enough memory even though the setting is only 10% lower.