Solved

SBS2011 and Exchange. "computer is responding slow to disk writes by an pervasive SQL app"

Posted on 2012-04-05
10
785 Views
Last Modified: 2013-12-02
OK my 2011 SBS server is running an app called "Fiber" and "Exchange" has 16 gigs of ram and i am curious about whether or not Exchange is hogging up all the memory forcing fiber to have to do more than normal disk writing. I know that in general computer terms a pc that is using all of its available memory is forced to constantly write to a hard drive rather than memory. I have attached a screen shot of the resource monitor and I have confirmed the drives are all good. To my understanding Exchange by default will use the remaining memory on the server to make it function better so maybe I should specify an amount if thats possible. I am looking for options here.
resourcemon-shot--1--4-5-12.jpg
0
Comment
Question by:calvinclose
  • 6
  • 4
10 Comments
 
LVL 28

Expert Comment

by:Bill Bach
Comment Utility
You can change your PSQL engine by changing the memory allocation there.  First, start by decreasing the L2 cache (Max Microkernel Memory Usage) to 0.  Then, you may wish to raise the L1 cache slightly to compensate, but only if your database size is substantially larger.

Second, you may want to change the SQLServer configuration to limit memory to a slightly smaller value, too.  Reducing this can leave more RAM available for other tasks.  It MAY also be possible to reduce the amount of RAM Exchange uses.  

Otherwise, you now see why Microsoft recommends running Exchange on its own dedicated server (and how they sell more operating system licenses).  It may be time for a second server to split the load.
0
 

Author Comment

by:calvinclose
Comment Utility
ok so after doing a lot of google university searching... I have saw a couple of possible results to modify the max and min amounts of cache ram that exchange uses, however this leads me to ask another question as well. If i change this will it also limit the amount of ram that ISS is allowed for its sql functions? Microsoft says that as far as physical Ram amounts on a network of less than 20 user 4 gigs of ram should be adequate but I would like to allow 8 gigs of ram instead (double the recommended amount) and still have 8 gigs of ram for other server operations.. possible problems would be that a rollup update could potentially and has changed these values back to there default. I am not 100% clear on the proper what to set the values so any help there would be greatly appericated. I am a bit unsure about the L2 cache adjustment what are the overall affects presented here. I don't see a processor max out occurring just slow writes to hard drive during database functions apparently due to exchange abusing memory optimization.
0
 
LVL 28

Expert Comment

by:Bill Bach
Comment Utility
Start small -- since PSQL is where your performance issues are right now, let's reallocate that memory first.  Once this is done, restart the engine and see how things go from there.  Perhaps Exchange will back off and not grab so much RAM if PSQL is given a bit more...
0
 

Author Comment

by:calvinclose
Comment Utility
can you explain the steps or provide a link to what you see is a good recommended way to do this.
0
 
LVL 28

Expert Comment

by:Bill Bach
Comment Utility
Start PCC, click "Configure Local Engine", go to the Performance tab.  Change Max Microkernel Memory Usage from 60 (default) to 0.  Increase the Cache Allocation size as you see fit.  It looks like this is a 32-bit engine, so a good start would be around 1GB (if you can afford that much memory for the database, and if your data files are larger than 1GB, of course).  Click OK to save the changes, then restart the box (or both services, if you know where that is).
0
How your wiki can always stay up-to-date

Quip doubles as a “living” wiki and a project management tool that evolves with your organization. As you finish projects in Quip, the work remains, easily accessible to all team members, new and old.
- Increase transparency
- Onboard new hires faster
- Access from mobile/offline

 

Author Comment

by:calvinclose
Comment Utility
Just as an update here we contacted the software people of the fiber program and they walked us through setting a larger amount of ram for prevasive to use default amount was 819megs they suggested bumping this amount to 4 gig and seeing what the exchange memory results would be. Now as it turns out after setting these options and restarting the server and attempting to log into Fiber the results were both very bad and unstable. Login's in some cases didnt work at all. Reseting this amount to default and rebooting the server brought things back to there previous state. I am now curious what to do next as a test to get the server to preform better. When Exchange is writing to the hard drive prevasive is able to do nothing but stop "freeze app" and wait, once exchange is done app unfreezes and normal function resumes.
0
 
LVL 28

Expert Comment

by:Bill Bach
Comment Utility
Why, in the name of the server gods, would they even THINK of doing this?  Increasing the database L1 cache to 4GB will exceed the memory addressing space available to a 32-bit process, and instantly cause the engine to fail.  Perhaps this makes sense on a 64-bit engine, but you are running a 32-bit engine right now.

Bring the L1 cache back down to 800-900MB and get it stable, first.  You can inch up the cache further if you want,. but just keep an eye on the Virtual Bytes for the process.  If you hit 2GB on a 32-bit OS or 4GB on a 64-bit OS, you'll be in trouble again.  More information about monitoring this setting can be found here:
http://www.goldstarsoftware.com/papers/UnderstandingServerMemoryCounters.pdf
http://www.goldstarsoftware.com/papers/InterpretingServerMemoryCounters.pdf
http://www.goldstarsoftware.com/papers/CapturingVirtualBytesToALogFile.pdf
0
 

Author Comment

by:calvinclose
Comment Utility
Well I am going to start looking over these links during the weekend and I will post more information as I attempt to make changes.. Thanks for you help this far and I am still wondering what lowering the amount of memory that Exchange can use will do. I am even under the impression that it may infact make exchange write to the hard drive more often and further worsen the symptoms that prevasive is having now. As far as why they suggested it the guy honestly sounded like he does it all the time.. so I am not sure what that means.
0
 

Accepted Solution

by:
calvinclose earned 0 total points
Comment Utility
ok so it took me a while to determine what would help and what would not.. Seems that i was correct with the problem being a hard drive access issue. Nothing I tried made a difference because it made no change in hard drive write times for prevasive. Now I did fix the issue but it required me adding a second drive to the server for the Fiber data to reside on. So at this point everything is working fine. Memory it seems was never an issue even though exchange is hogging it all up, prevasive is able to acquire what it needs as it needs it. Hope this helps someone out there if your having issues with slow app response times look at exchanges hard drive usage and you may find your problem there. Thanks for the help everyone.
0
 

Author Closing Comment

by:calvinclose
Comment Utility
glad i got this figured out
0

Featured Post

How to run any project with ease

Manage projects of all sizes how you want. Great for personal to-do lists, project milestones, team priorities and launch plans.
- Combine task lists, docs, spreadsheets, and chat in one
- View and edit from mobile/offline
- Cut down on emails

Join & Write a Comment

Disabling the Directory Sync Service Account in Office 365 will stop directory synchronization from working.
Learn to move / copy / export exchange contacts to iPhone without using any software. Also see the issues in configuration of exchange with iPhone to migrate contacts.
In this video we show how to create an Address List in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center. Navigate to the Organization >> Ad…
The video tutorial explains the basics of the Exchange server Database Availability groups. The components of this video include: 1. Automatic Failover 2. Failover Clustering 3. Active Manager

762 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

9 Experts available now in Live!

Get 1:1 Help Now