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  1. #1
    Join Date
    Mar 2014
    Posts
    5

    Unanswered: how to set max memory for sybase ase 12.5 on lnux(CentOS)?

    I have sybase 12.5 running on CentOS(this server is dedicated for sybase). There are 17G memory:
    [sybase@myserver ASE-12_5]$ free -g
    total used free shared buffers cached
    Mem: 17 7 9 0 0 7
    -/+ buffers/cache: 0 17
    Swap: 3 0 3

    there are 2G for ramdisk:
    [sybase@myserver ASE-12_5]$ df -h
    Filesystem Size Used Avail Use% Mounted on
    /dev/sda2 12G 2.6G 8.8G 23% /
    /dev/sda1 251M 19M 220M 8% /boot
    none 8.7G 0 8.7G 0% /dev/shm
    /dev/sdb1 30G 8.4G 20G 30% /home
    tmpfs 2.1G 20M 2.1G 1% /db/tempdb

    if reserve 1G for CentOS kernel, I think there should have 14G( = 17-1-2) available for sybase.

    So I tried in following way:
    1. Modify kernel.shmmax=14738890752 in /etc/sysctl.conf
    2. Reboot CentOS
    3. Modify ASE cfg fle to set max memory = 7196724

    then I can't start sybase. I change max memory = 4000000(2k) = 7.63G, then it is working.

    So question is:
    1. how much memory available for sybase ase fr my case?
    2. If Sybase always get all memory from shared memory set by kernel.shmmax?
    3. ramdisk should be exclude when calc shared memory?
    There are 2 rows from output of df - h:
    none 8.7G 0 8.7G 0% /dev/shm --this is set by system as default, 50% of total RAM
    tmpfs 2.1G 20M 2.1G 1% /db/tempdb --this is set manually

    For this case, should I reduce none to small, say 128M and release memory for Sybase?
    4. Why only 4000000(2k) available for sybase ase?

  2. #2
    Join Date
    Mar 2014
    Posts
    5

    how to set max memory for sybase ase 12.5 on lnux(CentOS)?

    I have sybase 12.5 running on CentOS(this server is dedicated for sybase). There are 17G memory:
    [sybase@myserver ASE-12_5]$ free -g
    total used free shared buffers cached
    Mem: 17 7 9 0 0 7
    -/+ buffers/cache: 0 17
    Swap: 3 0 3

    there are 2G for ramdisk:
    [sybase@myserver ASE-12_5]$ df -h
    Filesystem Size Used Avail Use% Mounted on
    /dev/sda2 12G 2.6G 8.8G 23% /
    /dev/sda1 251M 19M 220M 8% /boot
    none 8.7G 0 8.7G 0% /dev/shm
    /dev/sdb1 30G 8.4G 20G 30% /home
    tmpfs 2.1G 20M 2.1G 1% /db/tempdb

    if reserve 1G for CentOS kernel, I think there should have 14G( = 17-1-2) available for sybase.

    So I tried in following way:
    1. Modify kernel.shmmax=14738890752 in /etc/sysctl.conf
    2. Reboot CentOS
    3. Modify ASE cfg fle to set max memory = 7196724

    then I can't start sybase. I change max memory = 4000000(2k) = 7.63G, then it is working.

    So question is:
    1. how much memory available for sybase ase fr my case?
    2. If Sybase always get all memory from shared memory set by kernel.shmmax?
    3. ramdisk should be exclude when calc shared memory?
    There are 2 rows from output of df - h:
    none 8.7G 0 8.7G 0% /dev/shm --this is set by system as default, 50% of total RAM
    tmpfs 2.1G 20M 2.1G 1% /db/tempdb --this is set manually

    For this case, should I reduce none to small, say 128M and release memory for Sybase?
    4. Why only 4000000(2k) available for sybase ase?

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