Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Cached memory query

Posted on 2013-01-19
3
Medium Priority
?
290 Views
Last Modified: 2013-03-24
Running Windows 2008 Server (VM). The guest has been allocated 4GB RAM.

If I go to the Task Manager, I can see the following:

Physical memory (MB)
Total: 4094
Cached: 2456
Free: 74

The memory level picture in Task Manager shows 3.53 GB memory used.

Does this mean the machine is running out of memory? What does the "cached memory" actually do, is it being used or free?

And how does this fit in with page file usage? The page file is on the C: drive and has 5GB.
0
Comment
Question by:neil4933
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 31

Accepted Solution

by:
Frosty555 earned 2000 total points
ID: 38797663
For your purposes you can consider the cached memory to be "free".

Here's an example of Task Manager on one of my servers, a domain controller that is very lightly loaded for the amount of horsepower it has:

Task Manager
You can see the server has 12GB of memory. Yet it has 0MB free. In this case, the "Available" memory line item is what is telling the real story - the server has allocated all of the memory on the server but it is only using about 1.92GB of it.

Resource monitor gives a better picture without getting too deep into the specifics:

Resource Monitor
In reality only 1.9GB is actually in use. The rest is cached and in standby, but should basically considered to be free memory.


Regarding your swap file - for your purposes you can consider it to be unrelated to the rest of your memory situation, it is not being used in the calculations you posted in your question. It is just reserve memory in case the server runs out. Old or infrequently used pages of memory are swapped out into that file so that faster RAM can be used for more important things.

If the computer gets sufficiently low on memory that it actually has to start using the pagefile heavily, you'll know about it. The whole server will grind to a halt and you'll have severe performance issues.
0
 

Author Comment

by:neil4933
ID: 38798704
Hi Frosty

Thanks for the great explanation, really appreciate that :-)

So you would say that cached memory is actually "free" memory?

And the Memory/ Available Mbyes in Perfmon, is that a reliable counter to use in Perfmon, i.e. if it falls beneath 5-10% of the total RAM should we be worried, or does other factors like PAging coming into this?
0
 
LVL 31

Expert Comment

by:Frosty555
ID: 39016665
For the purposes of deciding if the server has adequate memory, the Available MBytes is reliable. Paging is an important metric, but it tells you different information.
0

Featured Post

[Webinar] Lessons on Recovering from Petya

Skyport is working hard to help customers recover from recent attacks, like the Petya worm. This work has brought to light some important lessons. New malware attacks like this can take down your entire environment. Learn from others mistakes on how to prevent Petya like worms.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article explains how to install and use the NTBackup utility that comes with Windows Server.
New style of hardware planning for Microsoft Exchange server.
This tutorial will walk an individual through configuring a drive on a Windows Server 2008 to perform shadow copies in order to quickly recover deleted files and folders. Click on Start and then select Computer to view the available drives on the se…
There are cases when e.g. an IT administrator wants to have full access and view into selected mailboxes on Exchange server, directly from his own email account in Outlook or Outlook Web Access. This proves useful when for example administrator want…

715 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