Debian virtual memory reaching limit

Posted by Gregor on Server Fault See other posts from Server Fault or by Gregor
Published on 2012-04-12T09:18:05Z Indexed on 2012/04/12 11:32 UTC
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As a relative newbie to systems, I inherited a Debian server and I've noticed that virtual memory is very high (around 95%!). The server has been running slow for around 6 months, and I was wondering if any of you had any tips on things I could try, particularly on freeing up memory. The server hosts various websites and also a Postit email server.

Here are the details:

Operating system    Debian Linux 5.0
Webmin version  1.580
Time on system  Thu Apr 12 11:12:21 2012
Kernel and CPU  Linux 2.6.18-6-amd64 on x86_64
Processor information   Intel(R) Core(TM)2 Duo CPU E7400 @ 2.80GHz, 2 cores
System uptime   229 days, 12 hours, 50 minutes
Running processes   138
CPU load averages   0.10 (1 min) 0.28 (5 mins) 0.36 (15 mins)
CPU usage   14% user, 1% kernel, 0% IO, 85% idle
Real memory     2.94 GB total, 1.69 GB used

Virtual memory  3.93 GB total, 3.84 GB used

Local disk space    142.84 GB total, 116.13 GB used

Free m output:

free -m
             total       used       free     shared    buffers     cached
Mem:          3010       2517        492          0        107        996
-/+ buffers/cache:       1413       1596
Swap:         4024       3930         93

Top output:

top - 11:59:57 up 229 days, 13:38,  1 user,  load average: 0.26, 0.24, 0.26
Tasks: 136 total,   2 running, 134 sleeping,   0 stopped,   0 zombie
Cpu(s):  3.8%us,  0.5%sy,  0.0%ni, 95.0%id,  0.7%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   3082544k total,  2773160k used,   309384k free,   111496k buffers
Swap:  4120632k total,  4024712k used,    95920k free,  1036136k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                              
28796 www-data  16   0  304m  68m 6188 S    8  2.3   0:03.13 apache2                               
    1 root      15   0 10304  592  564 S    0  0.0   0:00.76 init                                  
    2 root      RT   0     0    0    0 S    0  0.0   0:04.06 migration/0                           
    3 root      34  19     0    0    0 S    0  0.0   0:05.67 ksoftirqd/0                           
    4 root      RT   0     0    0    0 S    0  0.0   0:00.00 watchdog/0                            
    5 root      RT   0     0    0    0 S    0  0.0   0:00.06 migration/1                           
    6 root      34  19     0    0    0 S    0  0.0   0:01.26 ksoftirqd/1                           
    7 root      RT   0     0    0    0 S    0  0.0   0:00.00 watchdog/1                            
    8 root      10  -5     0    0    0 S    0  0.0   0:00.12 events/0                              
    9 root      10  -5     0    0    0 S    0  0.0   0:00.00 events/1                              
   10 root      10  -5     0    0    0 S    0  0.0   0:00.00 khelper                               
   11 root      10  -5     0    0    0 S    0  0.0   0:00.02 kthread                               
   16 root      10  -5     0    0    0 S    0  0.0   0:15.51 kblockd/0                             
   17 root      10  -5     0    0    0 S    0  0.0   0:01.32 kblockd/1                             
   18 root      15  -5     0    0    0 S    0  0.0   0:00.00 kacpid                                
  127 root      10  -5     0    0    0 S    0  0.0   0:00.00 khubd                                 
  129 root      10  -5     0    0    0 S    0  0.0   0:00.00 kseriod                               
  180 root      10  -5     0    0    0 S    0  0.0  70:09.05 kswapd0                               
  181 root      17  -5     0    0    0 S    0  0.0   0:00.00 aio/0                                 
  182 root      17  -5     0    0    0 S    0  0.0   0:00.00 aio/1                                 
  780 root      16  -5     0    0    0 S    0  0.0   0:00.00 ata/0                                 
  782 root      16  -5     0    0    0 S    0  0.0   0:00.00 ata/1                                 
  783 root      16  -5     0    0    0 S    0  0.0   0:00.00 ata_aux                               
  802 root      10  -5     0    0    0 S    0  0.0   0:00.00 scsi_eh_0                             
  803 root      10  -5     0    0    0 S    0  0.0   0:00.00 scsi_eh_1                             
  804 root      10  -5     0    0    0 S    0  0.0   0:00.00 scsi_eh_2                             
  805 root      10  -5     0    0    0 S    0  0.0   0:00.00 scsi_eh_3                             
 1013 root      10  -5     0    0    0 S    0  0.0  49:27.78 kjournald                             
 1181 root      15  -4 16912  452  448 S    0  0.0   0:00.05 udevd                                 
 1544 root      14  -5     0    0    0 S    0  0.0   0:00.00 kpsmoused                             
 1706 root      13  -5     0    0    0 S    0  0.0   0:00.00 kmirrord                              
 1995 root      18   0  193m 3324 1688 S    0  0.1   8:52.77 rsyslogd                              
 2031 root      15   0 48856  732  608 S    0  0.0   0:01.86 sshd                                  
 2071 root      25   0 17316 1072 1068 S    0  0.0   0:00.00 mysqld_safe                           
 2108 mysql     15   0  320m  72m 4368 S    0  2.4   1923:25 mysqld                                
 2109 root      18   0  3776  500  496 S    0  0.0   0:00.00 logger                                
 2180 postgres  15   0 99504 3016 2880 S    0  0.1   1:24.15 postgres                              
 2184 postgres  15   0 99504 3596 3420 S    0  0.1   0:02.08 postgres                              
 2185 postgres  15   0 99504  696  628 S    0  0.0   0:00.65 postgres                              
 2186 postgres  15   0 99640  892  648 S    0  0.0   0:01.18 postgres                              

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