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Former Member

Query in memory allocation of SAP/ORACLE in AIX system

Hello All,

We have configured around 76GB of physical RAM  in ECC system.  Moreover we found that only 300MB of free memory is available during business hours.

When we executed the below command at OS level during business hours, around 38GB of physical RAM is used (38GB of RAM should be free).  But in our case only 300MB free memory is available in the system

svmon -U -t 20 -i 10 -O summary=basic -O unit=GB

User                                 Inuse      Pin     Pgsp  Virtual

orasu1                                21.3     0.06     0.43     21.3

su1adm                              13.6     0.26     22.6     31.8

root                                      1.84     0.29     0.31     1.91

daaadm                               0.73     0.03     0.23     0.89

coda                                    0.47     0.04     0.04     0.50

sapadm                               0.37     0.03     0.12     0.45

uniq                                     0.16     0.04        0     0.13

nobody                                0.12     0.04        0     0.12

daemon                                0.12     0.04       00     0.12

bin                                            0        0        0        0

sys                                           0        0        0        0

adm                                          0        0        0        0

uucp                                          0        0        0        0

guest                                         0        0        0        0

lpd                                           0        0        0        0

lp                                            0        0        0        0

invscout                                 0        0        0        0

snapp                                    0        0        0        0

nuucp                                    0        0        0        0

ipsec                                    0        0        0        0

SAP Work process

Dia  BP BPA Spo Upd Up2 Enq Sum

75    20   -       3     9     4     1  112

sap Parameter value

EM/TOTAL_SIZE_MB = 31000

abap/heap_area_total  =  8000000000

abap/heap_area_dia     = 4000000000

abap/heap_area_nondia   = 4000000000

Oracle Parameter value

sga_max_size = 22G

pga_aggregate_target = 2G

db_cache_size      = 18496M shared_pool_size    = 1600M

My question is how we need to calculate the memory consumption of the system. As per the OS level around 40GB is used. But the current usage it shows only 300 MB free memory is available.  Please help me to solve this issue.

Regards

Subbu

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4 Answers

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    Former Member
    Jan 07, 2015 at 12:28 PM

    Can you in addition attach vmstat -v output?

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  • Jan 07, 2015 at 12:13 PM

    Hi Subbu,

    What else have you check ?

    Can you check the memory snapshot and topas. Map them once and see what else is running and consuming memory.

    Regards,

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  • Jan 07, 2015 at 02:02 PM

    HI Subbu,

    I hope there is some leak in memory area. check the CPU utilisation also.

    I have seen that memory area in SAP level and DB level.

    you can tune the parameter in DB side . I think there is no need 22GB for SGA area, better tune in SAP level.

    For more details check this link it might be helpfull. http://scn.sap.com/docs/DOC-59102

    you have to  analyse more on this which process occupying more memory.

    My suggestion parameter for your system.

    sap Parameter value

    EM/TOTAL_SIZE_MB = 21000

    abap/heap_area_total  =  10000000000

    abap/heap_area_dia     = 5000000000

    abap/heap_area_nondia   = 5000000000

    Oracle Parameter value

    sga_max_size= 16GB

    pga_aggregate_target = 2G

    db_cache_size     = 18496Mshared_pool_size  

    = 1600M

    Thanks,

    Brindavan

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    • Hi Subbu,

      Have you checked and found the issue about the leak memory area. The issue is 76GB Physical memory configured. But, SAP and DB occupying only 38 GB only memory and rest of the memory where its occupying only 300MB freespace ? If you think system  have to survive within  50GB of RAM and rest of the memory can be shared to some other sever, then tune the parameter accordingly. 

      And I am able to see the "Extended memory Max used size is 30 GB and current usage is 14.5 GB only . So better tune this parameter value for leaving the rest of the memory.

      If you want to configure the server within 50 GB of RAM and there is no performance issue? Could you please give more details on this.

      Thanks,

      Brindavan

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    Former Member
    Jan 08, 2015 at 11:57 AM

    Hi Subbu,

    Also bear in mind that AIX will use any free memory for its own buffering purposes.  For example, file system information will be put into memory if some is available.  The real question needs to be:  is there a performance issue?  If not, don't overly worry about 'free' memory.

    regards,

    Graham

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