[CentOS-es] Centos Memoria Cache

Estimados, antes que nada gracias por su tiempo.

Tengo el siguiente caso en un servidor de aplicación Jira de producción:

El servidor tiene 12 GB de RAM, se toma toda la ram y la guarda en cache como se puede ver a continuación:

# free -m total used free shared buffers cached Mem: 12011 11946 64 0 17 91 -/+ buffers/cache: 11837 173 Swap: 5951 7 5944

# top top - 15:04:29 up 8 days, 2:44, 1 user, load average: 0.06, 0.04, 0.01 Tasks: 133 total, 1 running, 132 sleeping, 0 stopped, 0 zombie Cpu(s): 0.6%us, 0.3%sy, 0.0%ni, 98.6%id, 0.0%wa, 0.3%hi, 0.3%si, 0.0%st Mem: 12299972k total, 12233816k used, 66156k free, 18436k buffers Swap: 6094840k total, 7244k used, 6087596k free, 93692k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ RUSER COMMAND 2 root RT -5 0 0 0 S 0.0 0.0 0:00.54 root migration/0 3 root 34 19 0 0 0 S 0.0 0.0 0:00.06 root ksoftirqd/0 4 root RT -5 0 0 0 S 0.0 0.0 0:00.36 root migration/1 5 root 34 19 0 0 0 S 0.0 0.0 0:00.07 root ksoftirqd/1 6 root RT -5 0 0 0 S 0.0 0.0 0:00.35 root migration/2 7 root 34 19 0 0 0 S 0.0 0.0 0:00.09 root ksoftirqd/2 8 root RT -5 0 0 0 S 0.0 0.0 0:00.31 root migration/3 9 root 34 19 0 0 0 S 0.0 0.0 0:00.11 root ksoftirqd/3 10 root 10 -5 0 0 0 S 0.0 0.0 0:02.98 root events/0 11 root 10 -5 0 0 0 S 0.0 0.0 0:02.13 root events/1 12 root 10 -5 0 0 0 S 0.0 0.0 0:01.90 root events/2 13 root 10 -5 0 0 0 S 0.0 0.0 0:01.53 root events/3 14 root 10 -5 0 0 0 S 0.0 0.0 0:00.00 root khelper 119 root 12 -5 0 0 0 S 0.0 0.0 0:00.00 root kthread 126 root 10 -5 0 0 0 S 0.0 0.0 0:01.76 root kblockd/0 127 root 10 -5 0 0 0 S 0.0 0.0 0:00.64 root kblockd/1 128 root 10 -5 0 0 0 S 0.0 0.0 0:00.83 root kblockd/2 129 root 10 -5 0 0 0 S 0.0 0.0 0:00.52 root kblockd/3 130 root 17 -5 0 0 0 S 0.0 0.0 0:00.00 root kacpid

Este es el proceso de la maquina virtual Java corriendo:

10285 ? Sl 204:16 /opt/java/jdk1.6.0_25/bin/java -Djava.util.logging.config.file=/apps/jira/jira402/conf/logging.properties -XX:MaxPermSize=256m -Xms3328m -Xmx3328m -Xmn1024m -XX:PermSize=1024m -Djava.awt.headless=true -Datlassian.standalone=JIRA -Dorg.apache.jasper.runtime.BodyContentImpl.LIMIT_BUFFER=true -Dmail.mime.decodeparameters=true -Duser.timezone=GMT-3 -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.endorsed.dirs=/apps/jira/jira402/common/endorsed -classpath /apps/jira/jira402/bin/bootstrap.jar -Dcatalina.base=/apps/jira/jira402 -Dcatalina.home=/apps/jira/jira402 -Djava.io.tmpdir=/apps/jira/jira402/temp org.apache.catalina.startup.Bootstrap start

Como pueden ver la aplicación Jira tiene configurado que utilice como maximo 4GB de Ram........

Paso la data del Sysstat:

# sar Linux 2.6.18-164.el5 (eze1-vnn-jira-demo) 05/10/2012

12:00:02 AM CPU %user %nice %system %iowait %steal %idle 12:10:01 AM all 0.71 0.00 0.22 1.83 0.00 97.24 12:20:01 AM all 0.03 0.00 0.02 0.01 0.00 99.95 12:30:01 AM all 0.01 0.00 0.02 0.03 0.00 99.94 12:40:01 AM all 0.09 0.00 0.02 0.02 0.00 99.87 12:50:01 AM all 0.05 0.00 0.02 0.09 0.00 99.85 01:00:01 AM all 0.25 0.00 0.04 0.12 0.00 99.59 01:10:01 AM all 0.05 0.00 0.02 0.05 0.00 99.88 01:20:01 AM all 0.02 0.00 0.02 0.04 0.00 99.92 01:30:01 AM all 0.02 0.00 0.02 0.01 0.00 99.95 01:40:01 AM all 0.09 0.00 0.02 0.05 0.00 99.84 01:50:01 AM all 0.03 0.00 0.02 0.01 0.00 99.94 02:00:01 AM all 0.03 0.00 0.02 0.06 0.00 99.90 02:10:01 AM all 0.05 0.00 0.02 0.01 0.00 99.92 02:20:02 AM all 0.02 0.00 0.02 0.06 0.00 99.90 02:30:01 AM all 0.01 0.00 0.01 0.02 0.00 99.96 02:40:01 AM all 0.00 0.00 0.02 0.04 0.00 99.93 02:50:01 AM all 0.03 0.00 0.02 0.01 0.00 99.94 03:00:01 AM all 0.00 0.00 0.01 0.01 0.00 99.98 03:10:01 AM all 0.05 0.00 0.02 0.06 0.00 99.87 03:20:01 AM all 0.02 0.00 0.01 0.01 0.00 99.96 03:30:01 AM all 0.00 0.00 0.02 0.01 0.00 99.97 03:40:01 AM all 0.04 0.00 0.01 0.01 0.00 99.94 03:50:01 AM all 0.03 0.00 0.02 0.01 0.00 99.95 04:00:01 AM all 0.00 0.00 0.02 0.04 0.00 99.94 04:10:01 AM all 0.37 0.00 0.11 1.41 0.00 98.11 04:20:01 AM all 0.02 0.00 0.01 0.07 0.00 99.90 04:30:01 AM all 0.03 0.00 0.05 0.04 0.00 99.88 04:40:02 AM all 0.07 0.00 0.10 0.03 0.00 99.80 04:50:21 AM all 6.77 0.00 0.92 1.50 0.00 90.81 05:00:01 AM all 6.18 0.00 0.38 2.05 0.00 91.39 05:10:01 AM all 0.22 0.00 0.03 0.03 0.00 99.72 05:20:01 AM all 0.02 0.00 0.02 0.01 0.00 99.95 05:30:01 AM all 0.01 0.00 0.02 0.03 0.00 99.94 05:40:01 AM all 0.00 0.00 0.02 0.01 0.00 99.97 05:50:01 AM all 0.03 0.00 0.02 0.01 0.00 99.94

05:50:01 AM CPU %user %nice %system %iowait %steal %idle 06:00:02 AM all 0.01 0.00 0.02 0.01 0.00 99.96 06:10:01 AM all 0.08 0.00 0.03 0.01 0.00 99.89 06:20:01 AM all 0.06 0.00 0.02 0.03 0.00 99.90 06:30:01 AM all 0.01 0.00 0.02 0.04 0.00 99.94 06:40:01 AM all 0.01 0.00 0.02 0.03 0.00 99.95 06:50:01 AM all 0.02 0.00 0.02 0.01 0.00 99.95 07:00:01 AM all 0.03 0.00 0.02 0.01 0.00 99.94 07:10:01 AM all 0.08 0.00 0.03 0.04 0.00 99.85 07:20:01 AM all 0.02 0.00 0.02 0.04 0.00 99.91 07:30:01 AM all 0.00 0.00 0.02 0.01 0.00 99.97 07:40:01 AM all 0.01 0.00 0.02 0.04 0.00 99.94 07:50:01 AM all 0.02 0.00 0.02 0.01 0.00 99.96 08:00:01 AM all 0.15 0.00 0.04 0.05 0.00 99.76 08:10:01 AM all 0.11 0.00 0.03 0.02 0.00 99.84 08:20:01 AM all 0.02 0.00 0.02 0.04 0.00 99.92 08:30:01 AM all 0.14 0.00 0.04 0.05 0.00 99.77 08:40:01 AM all 0.02 0.00 0.04 0.00 0.00 99.94 08:50:01 AM all 0.18 0.00 0.03 0.06 0.00 99.72 09:00:02 AM all 0.04 0.00 0.03 0.06 0.00 99.87 09:10:01 AM all 0.47 0.00 0.11 0.22 0.00 99.20 09:20:01 AM all 0.14 0.00 0.04 0.15 0.00 99.67 09:30:01 AM all 0.22 0.00 0.04 0.07 0.00 99.67 09:40:01 AM all 0.97 0.00 0.18 0.79 0.00 98.06 09:50:02 AM all 1.17 0.00 0.21 0.76 0.00 97.86 10:00:01 AM all 1.09 0.00 0.08 0.07 0.00 98.77 10:10:01 AM all 0.81 0.00 0.09 0.03 0.00 99.07 10:20:01 AM all 0.63 0.00 0.07 0.11 0.00 99.19 10:30:01 AM all 1.59 0.00 0.20 0.19 0.00 98.02 10:40:01 AM all 0.74 0.00 0.16 0.22 0.00 98.88 10:50:01 AM all 1.50 0.00 0.21 0.57 0.00 97.72 11:00:01 AM all 1.45 0.00 0.18 0.25 0.00 98.12 11:10:01 AM all 0.96 0.00 0.20 0.57 0.00 98.26 11:20:01 AM all 2.57 0.00 0.30 0.92 0.00 96.21 11:30:01 AM all 1.63 0.00 0.18 0.27 0.00 97.91 11:40:01 AM all 2.31 0.00 0.23 0.21 0.00 97.26

11:40:01 AM CPU %user %nice %system %iowait %steal %idle 11:50:01 AM all 3.17 0.00 0.28 0.24 0.00 96.31 12:00:01 PM all 8.44 0.00 0.54 0.68 0.00 90.34 12:10:01 PM all 1.14 0.00 0.23 0.14 0.00 98.49 12:20:01 PM all 1.13 0.00 0.24 0.08 0.00 98.55 12:30:01 PM all 0.60 0.00 0.15 0.06 0.00 99.19 12:40:01 PM all 0.60 0.00 0.11 0.09 0.00 99.19 12:50:01 PM all 1.20 0.00 0.20 0.59 0.00 98.01 01:00:01 PM all 1.40 0.00 0.32 0.27 0.00 98.01 01:10:01 PM all 0.92 0.00 0.19 0.19 0.00 98.69 01:20:01 PM all 0.82 0.00 0.17 0.07 0.00 98.94 01:30:01 PM all 0.08 0.00 0.04 0.16 0.00 99.72 01:40:01 PM all 0.15 0.00 0.03 0.02 0.00 99.80 01:50:01 PM all 0.23 0.00 0.05 0.04 0.00 99.68 02:00:01 PM all 0.37 0.00 0.10 0.10 0.00 99.42 02:10:01 PM all 0.16 0.00 0.05 0.01 0.00 99.78 02:20:01 PM all 0.35 0.00 0.07 0.05 0.00 99.53 02:30:01 PM all 0.26 0.00 0.06 0.06 0.00 99.63 02:40:01 PM all 0.29 0.00 0.07 0.06 0.00 99.59 02:50:01 PM all 1.04 0.00 0.21 0.18 0.00 98.58 03:00:01 PM all 1.24 0.00 0.27 0.19 0.00 98.30 03:10:01 PM all 0.98 0.00 0.18 0.12 0.00 98.72 Average: all 0.58 0.00 0.09 0.18 0.00 99.15

Pueden ayudarme a darme cuenta por que motivo se almacena tanta memoria en cache??

Muchas gracias,