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
top
orfree
. For example, I have no idea what this tool considers to be "used". I'm also pretty baffled what unused virtual memory would be. If it isn't used, then in what sense does it exist?