troubleshooting Question

How do I troubleshoot high load on a CentOs server?

Avatar of TheCybex
TheCybex asked on
Linux
13 Comments1 Solution1395 ViewsLast Modified:
Hi,

I have a dedicated webserver with CentOS 5.2 x64 installed. This webserver is dedicated for 1 websites (a vBulletin forum) with alot of members (approx. 350 users at the same time).

Server specs:
Intel Xeon X3220 @ 2,4Ghz (Quad core)
8GB memory
3x 160GB sata (no raid)

The serverload is getting really high occasionally for a couple of minutes, an output of top:

top - 13:59:35 up 23:58,  1 user,  load average: 42.04, 16.46, 16.27
Tasks: 215 total,  57 running, 158 sleeping,   0 stopped,   0 zombie
Cpu(s): 97.2%us,  2.7%sy,  0.0%ni,  0.0%id,  0.0%wa,  0.0%hi,  0.1%si,  0.0%st
Mem:   8182576k total,  4001496k used,  4181080k free,   522712k buffers
Swap:  8193108k total,        0k used,  8193108k free,  1902124k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                                    
 5745 apache    15   0  107m  22m 4000 S   10  0.3   0:33.63 httpd                                                                                      
 7594 apache    15   0  100m  18m 3548 S   10  0.2   0:16.20 httpd                                                                                      
 7717 apache    15   0  102m  19m 3444 S   10  0.2   0:02.34 httpd                                                                                      
 7588 apache    15   0  100m  17m 3524 S    9  0.2   0:18.26 httpd                                                                                      
 7615 apache    15   0  105m  22m 3604 S    9  0.3   0:09.52 httpd                                                                                      
 7622 apache    15   0  100m  17m 3564 S    9  0.2   0:09.42 httpd                                                                                      
 7623 apache    16   0  100m  17m 3516 R    9  0.2   0:10.60 httpd                                                                                      
 7681 apache    15   0  102m  19m 3456 R    9  0.2   0:02.38 httpd                                                                                      
 7601 apache    16   0  105m  22m 3520 R    9  0.3   0:11.35 httpd                                                                                      
 7654 apache    16   0  102m  19m 3524 R    9  0.2   0:02.16 httpd                                                                                      
 7667 apache    15   0  104m  21m 3464 S    9  0.3   0:02.35 httpd                      

Iostat output:

Linux 2.6.18-92.1.22.el5 (ecs.xxx.xxx)       01/05/2009

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
          44.74    0.02    2.60    0.12    0.00   52.52

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda               2.62        16.08       245.23    1389187   21182374
sdb               7.02        17.51       106.69    1512314    9215232
sdc               0.00         0.06         0.00       5130         72

I would like to know how I can troubleshoot this problem. When the serverload is high (40-60) the forum is almost dead (no reaction), but after a little while the serverload goes to 1.00 - 2.00 and it's back to normal.

Any idea's?

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