General :: Interpreting Output Of Memory Tools In RHEL 5.3?
Mar 15, 2010
I have been doing a lot of research on the web to piece together the components I need to understand what is probably a very simple thing. I've read up on buffers/cache vs. physical memory and using free -m and top and understanding that output, and reviewed Red Hat's article on virtual memory. I am hoping to get some assistance in putting it all together to understand what's happening in my situation because so far I have a lot of dangling factoids and no glue. I have also referenced the thread http://www.linuxquestions.org/questi...memory-309767/ but I didn't find my answer there.
My company is running a cluster of physical web servers (they are clones so running the same OS, with same RAM and applications installed). I'll be referring to a single system although the question applies to all because they're all showing similar output. The Multi Router Traffic Grapher is showing a steady swap usage for 3-4 months now. The average usage for today is 81%. There is, as far as I know, no performance hit because of it, but a developer noticed this and wanted to know what was going on, and I'd using this opp to learn. The system is Linux version 2.6.18-128.7.1.el5, running JBOSS, postgres, Apache, and Java. Here is the output from the memory commands I have used to try and understand what's going on.
So my interpretation of this output tells me that my system has 4GB of RAM installed, 23MB of free "physical" RAM, and 1.35GB of RAM in cache (according to the second line of free -m, which represents free physical memory and useable mapped memory if I understand correctly). I have a 2GB swap partition, 1.5GB of which is currently being used, and according to the MRTG is the average that has been in use since January. So the swap size isn't decreasing. Java (JBOSS) is using the most physical RAM at 1.6GB.
My question is: if I have 1.35GB of RAM cached, why is my system using all of that swap space and not using any of the cached RAM? I thought I understood that Linux is supposed to either re-use unmodified pages in cache or send older pages to disk when more RAM was needed. It seems like my system is always sending pages to disk, which I guess would normally mean I just need more RAM but, to have close to the same swap size consistently seems like there must be more to it.
I am trying to figure out the dir size of one of my dirs, and as far as I can tell the du command is the most appropriate for the job. However it doesn't appear to scan recursively correctly so I'm running the command independently on my 3 most important subfolders. One of them produces this output:
Code: DiskStation> du -sh /volume1/video/MOVIES 16777215.1T/volume1/video/MOVIES
I have written a manual backup script with menus using the dialog command. When using this on a centos 5(CentOS release 5.5 (Final)) server the output is the way I would like to have it. But when using it on our RHEL server (Red Hat Enterprise Linux Server release 5.3 (Tikanga)) it is almost unreadable. This RHEL server has been installed by another company so I don't know what they have configured.Now when I try to create a dialog box it is just waiting but not displaying anything.
how to find the memory map of any process? I used the pmap on unix. But my requirement is to check how much memory has been allocated from any library files. For example suppose i have one a.exe and it load one abc.so file which alloacate some memory. so can there be any utility to trace which memory is invoked by which .so file.
Is there a system admin tool for RHEL on montioring and logging system memory used and released that can dump to a log file?I'm having an issue with memory not being released when an application is closed. I need to have a tool monitor and log so I can troubleshoot to verify that it's an application not the OS.
I have been battling an issue for a couple of days and I have it down to 2 possibilities. Memory or mobo. A server in the DC is being very sketchy. Sometimes it will boot fine, sometimes it will boot but will not show all the memory, and sometimes it will hang before it even posts. I have replaced just about everything inside the system except for the memory and the mobo.
I would like to test the memory before replacing either because both are a few hundred dollars. The problem is, the memory doesn't log any errors and running a memory test with ubcd doesn't work because it's ecc memory. I thought I remembered hearing that there is a way to run a memory test during a Centos or RHEL installation, but I can't figure out how.
I have a RAID1 array, where mdadm states that one of the disks is "removed." Naturally, I assume one of the drives has failed. The mdadm --detail command tells me that the sda drive has failed. However, further inspection from the mdadm -E /dev/sdb1 command says that sdb1 disk has been removed. I am a bit confused. Can someone clarify which drive is failed? Am I misreading the command outputs?
When you execute this in the command line it prints a bold green 'OK'. So far so good.
Now, I need to check the output of the script over time using the command watch. The problem then arises. watch seems to ignore the escape codes and just prints:
Code: [1;31;32mOK [00m
Is there any way to fix this?
If not, how can I check inside the script if it is being executed from a command? (watch in this case) So I can print without color for those cases.
can not ping from host (RHEL 6) to RHEL 5 in (virtual)? I have stopped iptables on both machines. But still not able to ping from host machine to virtual.
I ran two scans in Zenmap: 1) Quick scan plus and 2) Quick Traceroute. Quick scan plus, under the Nmap Output tab, has a field called "Network Distance". The Quick Traceroute report under the same tab lists the HOP and RTT time. I was thinking that for a given server, the value for the Network Distance would be the same as the HOP field when initiating the scans from the same server, but they are not.
I am using malloc and frees a lot in my program. It shows its allocated but when i remove it doesnt show as the memory is removed(I am using the top command to view VIRT memory usage). If this continously grows what would happen to my program (Will it go out of memory?)
I have a computer with 16GB of ram. At the moment, top shows all the RAM is taken, (NOT by cache), but the RAM used by the various processes is very far from 16GB.I have seen this problem several times, but I don't understand what is happening.My only remedy so far has been to reboot the machine.
I am trying to download RHEL 5.4 AS version for testing..But under [URL] There is no specific link for AS version or ES version..How can I detect which iso is for AS and which one for ES..? There are separate links for AS and ES version for RHEL 4.x version but why is it not available for RHEL 5.x versions?
This package contains tools to manage Debian based XEN virtual servers.
Using the scripts you can easily create fully configured Xen guest domains (domU) which can be listed, updated, or copied easily.
Homepage: [url] in the above output I am getting a line Conffiles and then you can see a series of /etc what are that and is it an error or some conflict?
This is my first post in these forums. I'm still quite new to Linux (using Mint 9) so please bear with my not-very-articulate question(s)When I boot up and open up a tty terminal I get a message saying "Memory corruption detected in low memory." I've done an extensive google search about the issue and it seems not uncommon. I ran a memtest with no errors returned, so I'm sure that there's nothing really wrong with the memory; apparently it's a bug in the kernel that's causing this.
I found from command 'top' that 8GB memory are used. However, using command 'ps' with some options to grep the running processes and then summing up the memory used by the running processes are less than 2 GB. Where has the used memory gone ?
i have old RHEL 3 system which has kernel 2.4 installed into it. I wasnt to upgrade it to RHEL 5.x so i downloaded a kernel 2.6 package but was not able to compile it.
is possible to edited the default RHEL CD to have it automatically install RHEL based off of a kickstart file that I will store locally on the CD. My plan would be to put a cd in a server and have the OS automatically being installed.
We are planning to migrate our LINUX server from RHEL 3to RHEL 5. What are the configuration difference between RHEL 3 to RHEL 5 for webserver installations?
I'm looking to install a Linux distro on my Windows 7 machine. Could anyone suggest any tools to handle the multiboot? (I may install 2-3 distros to try out)
Updating my kernel corrupted grub preventing me from booting. Running the grub shell to restore the primary stage bootloader, restored bootability. It is important to note, that several months ago, I had a similar failure that corrupted the MBR.Are there any Linux based tools to check an HD for sanity? By the latter I am not only understanding software integrity but also hardware sanity.
