Hello,

please can anyone share the script or application which allows quick discovery what is causing high load on Linux server?

I mean if its HDD I/O or CPU or RAM or Network overload?

So far i found command:
Code:
iostat 5 4;echo "---RAM USAGE---";echo "";free -m | grep buffers;echo "";echo "---DISK SPEED---";dd if=/dev/zero of=test bs=64k count=1k conv=fdatasync;rm -rf test;echo "";
Name: iostat_free-m_dd_.png Views: 661 Size: 12.6 KB

%idle is how much CPU is free (so there we see CPU is not issue)
tps is HDD transactions per second. Standard 7000RPM HDD is like up to like 110tps, if more, then %iowait value is raising and server is lagging and delaying


If high tps (HDD is cause) then one can do following commands to discover top HDD processes:
Code:
iotop -ao
iotop -o -b -n 1 -d 2 -t
DSTAT & NMON

"nmon" for linux. Install:
A) Centos 6,64bit: rpm -ivh http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm
B) Centos 5,64bit: rpm -ivh http://apt.sw.be/redhat/el5/en/x86_64/rpmforge/RPMS/rpmforge-release-0.5.2-2.el5.rf.x86_64.rpm

yum install nmon -y

nmon returns like:
Name: nmon_linux_cpu_hdd_net_monitor.png Views: 335 Size: 31.0 KB

command: nmon and then type: v,l,d,n,m (vldnm) h for help

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install "dstat" which shows, cpu usage, hdd bandwidth, network usage

Name: dstat_linux.png Views: 321 Size: 10.8 KB
(it don't show HDD transactions per second - tps which is often more important than data bandwidth)

dstat -vts --disk-util --top-io --top-bio --noheaders --nocolor
Code:
---procs--- ------memory-usage----- ---paging-- -dsk/total- ---system-- ----total-cpu-usage---- ----system---- ----swap--- sda- ----most-expensive---- ----most-expensive----
run blk new| used  buff  cach  free|  in   out | read  writ| int   csw |usr sys idl wai hiq siq|  date/time   | used  free|util|     i/o process      |  block i/o process
  0   0  51|9.95G  470M 9.91G 3161M|   2B   17B|1073k 1158k|8443    12k|  5   1  92   1   0   0|27-05 09:32:13|  51M   12G|25.3|mysqld       21M 6500k|init        489k  318k
3.0   0  24|9.99G  470M 9.91G 3119M|   0     0 |   0   500k|9047    14k|  5   2  93   0   0   0|27-05 09:32:14|  51M   12G|2.30|mysqld       73M  145k|denyhosts.p   0   500k
3.0   0  22|10.1G  470M 9.91G 3046M|   0     0 |8192B  316k|  10k   14k|  8   2  89   0   0   0|27-05 09:32:15|  51M   12G|9.10|mysqld       14M  268k|denyhosts.p   0   112k
2.0   0  19|10.1G  470M 9.91G 2958M|   0     0 |   0    24k|9304    14k|  9   2  89   0   0   0|27-05 09:32:16|  51M   12G|0.20|mysqld       31M   17M|httpd         0    24k
3.0   0  12|10.0G  470M 9.91G 3097M|   0     0 | 108k  444k|8702    14k|  5   2  93   1   0   0|27-05 09:32:17|  51M   12G|15.6|mysqld       17M  227k|jbd2/dm-0-8   0   128k
1.0   0  27|9.98G  470M 9.91G 3128M|   0     0 |   0   132k|7916    13k|  4   2  94   0   0   0|27-05 09:32:18|  51M   12G|10.6|init       1722k  648B|init          0    20k
For the bash script usage, one can do: dstat -vts --disk-util --top-io --top-bio --noheaders --nocolor 5 3 > logfile