Average load extremely high, no cpu used

[Andrea Gangini]

Hi, I noticed this behavior on one of my server (mail server, postfix + 
amavisd + spamassassin, 2,8ghz Xeon, kernel 2.6.9-1.681_FC3smp).

Here's the output of top command:

top - 15:04:35 up 4 days,  6:33,  2 users,  load average: 15.00, 15.03, 
15.05
Tasks: 160 total,   1 running, 159 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.2% us,  0.2% sy,  0.0% ni, 99.7% id,  0.0% wa,  0.0% hi,  0.0% si
Mem:    505484k total,   405564k used,    99920k free,    10836k buffers
Swap:  1052152k total,    33032k used,  1019120k free,    62548k cached


Here's vmstat 3:
procs -----------memory---------- ---swap-- -----io---- --system-- 
----cpu----
  r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us 
sy id wa
  1  0  33032 100112  10924  62720    1    1     5    36    8    36  1 
0 99  0
  0  0  33032 100112  10936  62708    0    0     0    56 1022   126  0 
0 100  0
  0  0  33032 100112  10944  62700    0    0     0    29 1032   133  0 
0 100  0
  0  0  33032 100112  10952  62692    0    0     0    64 1040   124  0 
0 100  0
  0  0  33032  99336  10988  62656    0    0     0    97 1053   214  0 
1 99  0

The machine is apparently under NO load, NO cpu used, all services run 
at great speed (postfix, samba, webmin) and no apparent problems.

Any clues/suggestions?


-- 
Andrea Gangini, Mimesi S.r.l.
a.gangini at mimesi.com
Tel. 0521/463811