Server :: Difference Between IOWAIT% / IDLE% / LOAD AVG?
Oct 27, 2010
Can anyone explain the difference between IOWAIT%/IDLE%/LOAD AVG? We have a 3 servers (oracle rac) attached to a SAN. When we added another CPU to our 3rd server, the IOWAIT across the oracle rac dropped a lot. We used to get pretty high IOWAIT % before. So I don't really understand how the extra CPU could do this. I thought the IOWAIT % is high because the server is waiting for the SAN, so I thought the SAN was the bottleneck. So I don't really understand the difference between the 3 things (iowait, idle and load avg).
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Jul 24, 2011
I run a website that a very steady flow of traffic and Im seeing recent issues that I just dont like. Server is 10.04.2 on a supermicro i7-950/6gb RAM with two 500gb Samsung F3 drives in a software RAID1 (1x5400, 1x7200) and for several weeks, its been running very well. Recently, Im seeing the server hang for 5-20 seconds. IOwait goes through the roof, nothing can write to the disk. Apache logs stop, redis fails to rebuild caches, mysql errors and then it continues and moves back to normal operation
/ is ext4, the kernel was 2.6.32-server-x64 but since updating to 2.6.38-server-x64, the issue has dropped from maybe once per 10 minutes to once per 15 minutes. 3 IOstat copy/pastes show this when it hangs.
Code:
Total DISK READ: 0.00 B/s | Total DISK WRITE: 0.00 B/s
TID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND
[code]...
No smart errors or smart diags show any issues with any of the disks and kernel.log shows near nothing other than a process hang, 120 seconds about 5 days ago.
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Nov 2, 2015
I had noticed that my workstation (running debian testing) is having a constant load of about 0.9 (+/-0.1), even while the system is completly idle.The system starts with a normal load and then goes up to about 0.9 within a few minutes and then will stay there forever (well it can get higher, but never lower). This is the load graph after the system runs some time: URL....
I have tried everything I know to find the cultprint but there is no cpu usage and no io usage. I even have disabled the desktop and still have this problem.Also I have tried booting an older Kernel (4.1 and 3.16) with no difference in the load.Here is some information about my system:
Code: Select all» uname -a
Linux localhorst 4.2.0-1-amd64 #1 SMP Debian 4.2.3-2 (2015-10-14) x86_64 GNU/Linux.
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May 5, 2010
Since upgrading from 9.10 to 10.04, my system is noticeably less responsive and exhibits halting behavior for at times 10s of seconds. There is nothing obvious in the various logs that I can find. The only objective indication I can find that demonstrates that something is seriously wrong is that my load average never drops below 0.5 and is often over 1.5, even at idle. In this situation, top/ps/whatever shows very few processes running (usually just top). This suggests to me that either the new kernel scheduler is horrible or that something new is resulting in blocking I/O or other uninterruptable sleeps.Typical top output:
Quote:
top - 12:18:01 up 1 day, 49 min, 5 users, load average: 1.42, 0.86, 0.71
Tasks: 262 total, 1 running, 261 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.9%us, 0.8%sy, 0.0%ni, 97.6%id, 0.0%wa, 0.0%hi, 0.7%si, 0.0%st
[code]....
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Dec 7, 2010
I recently upgraded from Fedora 11 to Fedora 14 on my Dell Latitude E6400 notebook PC. It's a Dual core processor, as seen in the uname provided below:
uname -a:
Linux COMPUTERNAME 2.6.35.6-48.fc14.i686 #1 SMP Fri Oct 22 15:34:36 UTC 2010 i686 i686 i386 GNU/Linux
redhat-release:
Fedora release 14 (Laughlin)
Since the upgrade, I've noticed some unexplainable behavior: The load average is consistently 0.5 - 1.75 when my PC is completely idle (99% according to top). No processes are in the D (I/O) state, and I have no Zombie processes. This happens on a fresh boot, every time. It gets worse and less worse, and bounces from unusable (cursor stops moving as I type in the terminal, to actually losing keystrokes at times). I'm wondering if anybody else is experiencing similar issues, or knows of a (the) kernel bug which is causing this behavior? Actively researching the issue. I've come across the following: Tens of wakes per second in "[kernel scheduler] Load balancing tick" on Core 2 Duo even with only 1 core enabled
[Code]....
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Nov 26, 2010
I am having a problem with the server that I use to host my personal site. The load average quite often spikes to exceed 1.00 for the 1 and 5 minute intervals, and the 15 minute interval gets above .5. This occurs while the server is idle, serving very few or no requests and with the CPU 99% idle with <1% IOWAIT usage. I have checked top and vmstat, but neither one provides any useful info. Top continues to say the CPU is 99% idle, and vmstat says that there are 0 runnable and 0 blocking tasks. Occasionally, vmstat will say that there is 1 runnable task, but this doesn't even coincide with the load average spikes. I have already searched for other solutions to this problem, but everything I have seen says to use top and/or vmstat, but those aren't showing anything out of the ordinary. Can anyone recommend anything else I might do?
My server has a Pentium 4 HT 3gHz processor, 2GB RAM, and runs Kubuntu 10.10. (The reason it runs Kubuntu instead of Ubuntu Server is that it needs an X environment so that the Nvidia driver can initialize and put its graphics card into a power saving mode.)
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Mar 22, 2011
When I run top d 0.5 on my machine and I press 1 to enable the SMP View, I notice that all of the CPUs keep toggling between 100%idle and 0% idle.
The odd part is that when a CPU goes to 0.0% idle, I would expect to see one or more of the other columns peek, but they are not.
What is causing this?
Code:
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May 28, 2011
Most of the time when using USB flash drives under Linux, the OS will lock up at 100% IOWAIT, with a load average of 12-18. Even my music stutters and stops. Using USB drives makes my Core I7 3.0GHz HyperThreaded act like a Pentium 2 running Vista. It's embarrassing. A client asks for a file, and it takes me 2 hours to copy it. This is a deal breaker. I've been trying to find a solution. If I can't, I'm sorry to say I'll be leaving Linux for something that can use USB drives. I've been using Ubuntu for 4 years, I'd hate to leave. Don't take that as threat, just a stark fact based on business decisions.
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Jan 5, 2010
I've been having a problem in Ubuntu 9.10 recently where starting about 2 minutes after startup my computer slows down and becomes unresponsive. I believe the problem is associated with a high IOWait because I have the system monitor applet on my Gnome Panel and it displays 100% IOWait every time my system starts to slow down.
I have tried booting into other kernel version and the problem persists. I don't really know what IOWait is or how to diagnose this problem further. I've looked around online and it seems like you have to find a specific process that is causing the IOWait, but I don't understand how to go about doing that.
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Jan 5, 2010
I've been having a problem in Ubuntu 9.10 recently where starting about 2 minutes after startup my computer slows down and becomes unresponsive. I believe the problem is associated with a high IOWait because I have the system monitor applet on my Gnome Panel and it displays 100% IOWait every time my system starts to slow down. I have tried booting into other kernel version and the problem persists. I don't really know what IOWait is or how to diagnose this problem further. I've looked around online and it seems like you have to find a specific process that is causing the IOWait, but I don't understand how to go about doing that.
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Apr 14, 2010
I boot it and let him stay alone without even log-in,then thru my local LAN I access the server with SSH or FTP, everything just works fine,but if I just let the server idle for a while, I stop being able to login to the server again.I get no response, and when I go check it , monitor is black, like its sleeping,Then I just press a key on the keyboard, it wakes, and I can login from the server itself.so it does not crash.But login from another computer still doesn´t work,I have to reboot the Linux server to work, and all this idle thing starts over again.
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Nov 10, 2010
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May 29, 2010
i've gotten my fedora 12 to the point where i can run python3 scripts from command line and can call up python 2.6.2 idle with the command 'idle' from command line. what command will call up python3 (3.1.2 to be exact) idle?
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Apr 6, 2009
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Aug 7, 2011
I own a rather large website/forum devoted to Scuba utilizing vBulletin. The problem is that its become INCREDIBLY slow as of late. I have three Ubuntu web servers under a single Ubuntu load balancer and they draw from a CentOS 5 DB server running MYSQL. Here are my concerns:
-I am thinking that they are all 32 bit rather than 64 bit.
-I am thinking that the problem is an IO issue.
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Jul 20, 2010
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May 3, 2010
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Feb 19, 2011
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Mar 3, 2011
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Sep 8, 2009
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Jan 19, 2010
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May 4, 2009
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Mar 13, 2011
I got this type of messages:k journald starting. commit interval 5 seconds.EXT3.fs:mounted file system with ordered data modefreeing unused kernel memory : 212 k freed.Warning:unable to open an initial consoleAfter this Server is not hang state but stay at same Anybody can help me how to resloved this type of issue.
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Nov 25, 2010
I have a Centos 5.5 server and I had a problem with its time because it was 1 one hour ahead of my local time. I installed and activated NTP and I created a link for /etc/localtime:
Code:
ln -sf /usr/share/zoneinfo/America/Mexico_City /etc/localtime
I reboot the server and waited for 1 hour but the time wasnt correct. The server's BIOS clock has UTC time so I edited /etc/sysconfig/clock file replacing:
Code:
UTC=false for
UTC=true
I reboot the server and waited for 1 hour but the time wasnt correct. After breaking my head for about 1 hour, I realized that there is a directory /usr/share/zoneinfo/Mexico and changed my link for /etc/localtime
Code:
ln -sf /usr/share/zoneinfo/Mexico/General /etc/localtime
And It worked. What is the difference between America/Mexico_City and Mexico/General files in /usr/share/timezones, they should be identical but of course they are not?
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Sep 19, 2010
I run a server with nginx at the front and apache at the background. Nginx serves as a reverse proxy in here. As there were lots of DOS attacks, I have implemented Deflate-DDOS, APF and Nginx anti-ddos features and the server runs without a problem. Once every month, the load on server increases upto 300 and I receive an email like this :
Subject : Cron <root@server> [ -x /usr/lib/php5/maxlifetime ] && [ -d /var/lib/php5 ] && find /var/lib/php5/ -type f -cmin +$(/usr/lib/php5/maxlifetime) -print0 | xargs -n 200 -r -0 rm
Content :
find: `/var/lib/php5/sess_0ca40520ac8ecb66090746f90da17516': No such file or directory
find: `/var/lib/php5/sess_3839b0cbf042934183d56ff682c948e0': No such file or directory
find: `/var/lib/php5/sess_dec1ed8ea1f62caf7a42a29b9f82c506': No such file or directory
[code]....
There's more that 100,000 ( I suppose ) lines on this email. I have no idea what the problem is. It seems there's something with the session, but I really don't know what it is.
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