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I am hoping that some of you may be able to help me.
I have done a search and found a few things, but I am still a bit unsure if there is any solution for this problem.
I know you will probably tell me that this is a feature of Linux and not a bug, but I’m sure that system should not freeze and also use the page file.
The problem that I am having is my Red Hat (v9.0) server is holding on to it’s memory, and this is causing slight freezes / delays in the system. The “Freeze” will last approximately 0.5 to 1 second during which time nothing can be done of the system, anything that is typed is not displayed (i.e. The system does not catch up).
Users are experiencing a number of problems when navigation through the file system, ‘VI’ing’ files and using files via Samba that are stored on this file server.
I have tried a number of things, but don’t seem to be able to stop this “Freezing”
Below is a list of things I have noticed:
vi – If I vi a file it uses 50mb of memory the 1st time I open it. If I then close the file it drops 20mb of that usage and any subsequent file opening will only use an extra 20mb (i.e. every time a file is vi’d it will use 30mb of the system memory that I don’t get back)
Textpad via Samba – If I open a file using textpad (text editor) via a samba share on the machine it will use 20mb of memory, this will not drop off after the file is closed.
Moving data via samba – If I move data to and from the file server via Samba / explorer all of the systems memory is used, this is not dropped off after the move has completed. The only way the memory usage drops off is if the data is deleted from the fileserver.
I have noticed that the system will use about 70mb or 80mb of the page file.
We are running:
ABIT IT7-MAX2 MB
2 x 1GB PC333 DDR
1 x 40GB Boot disk
2 x 120GB RAID Data disks (RAID on MB)
32MB AGP Graphics card
This machine is a file server for 5 Linux computational nodes and also users log on to this server using hummingbird exceed (kterm)
On the face of it you don't seem to have a problem.
I presume you are on a 2.4 kernel ???. 2.6 introduced a "swappiness" sysctl to give you some flexibility in balancing the usage of storage to better suite your (i.e. the administrators) desires.
I don't know that you have a lot of options if you are on 2.4.
 forgot about iowait - have a look at the top display(s) - you don't have an issue (0.0%)
I'm the wrong guy to ask - all my systems are at 2.6, and except for "packaged" distros like Ubuntu or Mepis, are at 2.6.15 or later.
No (stable) servers here buddy ...
There are certainly benefits - and I don't agree with those that say the alleged stability of 2.4.x has been lost. For your situation you might want to cruise by and have a look at something like Centos (RHEL for the masses).
I happen to think swappiness might help relieve your situation - presuming it's not just something like bad DMA settings. Doesn't look like it - bugger all I/O in that (short) snapshot.
The above output likewise the earlier one you posted shows that the system is really not actively using that much memory, as as much as ~ 1700mb is cached.
There should be no reason whatsoever to worry about swap with 2gb of ram.
Like suggested, upgrading to 2.6 kernel might be a good choice. Actually I would do it anyhow already because security etc. reasons. And never ever have experienced stability problems with 2.6. kernels.
You might want to track the issue with e.g. 'vmstat -an 2' which gives a better outlook to for instance io loads. However, my guess is that the problem is not really directly related to memory but to some software issues (e.g. what about the Samba itself?).
The load on both the CPU and RAM are pretty light - as syg00 mentioned "free -m" is a great way to determine how your RAM is being used. The "+/- buffer/cache" is what matters, and shows you what is actually really being used.
If these issues started to occur after a new disk was installed, maybe it isn't using DMA. What are the results of
(assuming your boot drive is /dev/hda)
You'd want to see "using_dma = 1(on)", and more info can be found here
Also, I'd suggest checking how full your drives are, sometimes a system will hiccup if the amount of free space gets too low. Good luck with it