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Linux Memory utilization [message #563228] Fri, 10 August 2012 04:49 Go to next message
gkrishn
Messages: 491
Registered: December 2005
Location: Putty a dark screen
Senior Member
Hi, i have 46GB physical memory.
20GB used by DB1, 4GB used by DB2, and 300MB used by ASM.
But any idea why its not showing any free space in system ? any tip ?

oracle@localhost:> uname -r
2.6.18-274.12.1.0.1.el5

oracle@localhost:> free -g
             total       used       free     shared    buffers     cached
Mem:            46         46          0          0          0         41
-/+ buffers/cache:          4         42
Swap:            7          1          6


top - 05:39:05 up 103 days,  2:09,  4 users,  load average: 2.03, 2.07, 2.00
Tasks: 419 total,   1 running, 418 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.2%us,  0.1%sy,  0.0%ni, 93.2%id,  6.4%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:  49188248k total, 48488160k used,   700088k free,   817564k buffers
Swap:  8385920k total,  1520108k used,  6865812k free, 43329600k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
15494 oracle    16   0 4366m 3.3g 3.3g D  2.3  7.1   1:05.98 oracle
 1407 oracle    15   0 4341m 2.4g 2.4g S  1.0  5.2   0:33.53 oracle
18159 root      34  19  298m  41m  34m D  1.0  0.1   1:58.24 clBackup
 1403 oracle    15   0 4343m 2.3g 2.3g S  0.7  4.9   0:20.48 oracle
 1395 oracle    18   0 4332m  30m  26m S  0.3  0.1   0:40.06 oracle
 1411 oracle    15   0 4353m  56m  52m S  0.3  0.1   0:12.96 oracle
16545 oracle    18   0 19.8g  55m  47m S  0.3  0.1   5:52.82 oracle
29436 root      15   0  2604 1360  872 S  0.3  0.0  13:23.23 cmahostd
    1 root      15   0 10368  724  600 S  0.0  0.0   1:09.51 init
    2 root      RT  -5     0    0    0 S  0.0  0.0   0:09.34 migration/0
    3 root      34  19     0    0    0 S  0.0  0.0   0:00.03 ksoftirqd/0


# Database-1
SQL> show parameter sga

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
lock_sga                             boolean     FALSE
pre_page_sga                         boolean     FALSE
sga_max_size                         big integer 20032M
sga_target                           big integer 10048M


# Database-2

SQL> show parameter sga

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
lock_sga                             boolean     FALSE
pre_page_sga                         boolean     FALSE
sga_max_size                         big integer 4G
sga_target                           big integer 4G

# ASM 
SQL> show parameter memory

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
memory_max_target                    big integer 304M
memory_target                        big integer 304M

Re: Linux Memory utilization [message #563230 is a reply to message #563228] Fri, 10 August 2012 05:10 Go to previous messageGo to next message
John Watson
Messages: 4802
Registered: January 2010
Location: Global Village
Senior Member
But you have masses of available RAM, you are using only 4G. The rest is all disc cache.
Re: Linux Memory utilization [message #563231 is a reply to message #563228] Fri, 10 August 2012 05:12 Go to previous messageGo to next message
ThomasG
Messages: 3114
Registered: April 2005
Location: Heilbronn, Germany
Senior Member
The Important line is :
-/+ buffers/cache:          4         42


Basically only 4GB is really used as "RAM" by Oracle at the moment.

The OS is using 42GB as buffers and cache. Which is a good thing. Having RAM "free" is basically a waste of RAM. Any "free" RAM that is currently not used by programs and processes is used to buffer disk data for faster access.
Re: Linux Memory utilization [message #563233 is a reply to message #563231] Fri, 10 August 2012 05:19 Go to previous message
gkrishn
Messages: 491
Registered: December 2005
Location: Putty a dark screen
Senior Member
THANKS both. i am learning a new concept.

Line1:Mem , i need to check only Total physical memory available.
Line2:buffers , I need to check used(4GB by programs) , and free (Linux use this as cache for faster access to data).
Line3:Swap , i think this will be fully used only if line2 Used is 100%.

am i right ?

and what about mem used by OS .. Line:2 (4GB) include that aswell or just non-OS memory.
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