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Sybase IQ Multiplexing and Linux OS

Former Member
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I have two servers for IQ, WRITER and READER.  I have implemented multiplexing on it.
Multiplexing is running smoothly.  I checked by connecting both servers indivisualy using ISQL, both servers WRITER and READER are connecting and working fine.

But whenever I tried to execute any command on host machine (on linux), it is giving me error / message as "resources not available".  After then if i killed process for Sybase IQ server (using another session) on READER, I can properly execute any command on linux host.

I am not sure wether the problem is of Linux host or multiplexing setup.

Linux Version : 2.6.32-279.el6.x86_64 #1 SMP Wed Jun 13 18:24:36 EDT 2012 x86_64 x86_64 x86_64 GNU/Linux
Sybase IQ Version : Sybase IQ/15.3.0.6056/110506/P/GA/Enterprise Linux64 - x86_64 - 2.6.9-67.0.4.ELsmp/64bit/2011-05-06 13:27:43


Is there anything that I have to change on linux server? or in multiplexing setup?

Waiting for reply.

Thanks,

Accepted Solutions (0)

Answers (2)

Answers (2)

Former Member
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We have as of now following setting on /etc/security/limits.conf

sybase           soft    nproc           1392

sybase           hard    nproc           2784

Is it sufficient or I need to increase it?

We have 32 CPU's on the servers in which i have assigned 20 CPU's for IQ using configuration file.

-iqnumbercpus 20

I am going to increase no of CPU's to 25 - 30 in future.

Accordingly what changes i have to make on linux host?  Do I need to increase soft and hard nproc on host?

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I would recommend to set this both to 64K at minimum

Regards

markmumy
Advisor
Advisor
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Check out the Linux Release Bulletin known issues section. This is a redhat 6 configuration change that requires modification of the OS to work.

  • RH 6.x default setting for max user processes may be too low for starting SAP Sybase IQ servers – Red Hat 6.x introduced a change that affects the number of threads that the SAP Sybase IQ engine can start. By default, Red Hat 5.x set the limit dynamically based on the machine configuration. (For example, an 8-core system would set the limit at 256693.) In Red Hat 6.x, this limit is hard-coded to 1024 regardless of system size. This change particularly affects systems with high CPU per core counts and systems where the same user account starts multiple IQ servers.
  • Workaround 1
    1. Calculate the number of threads needed. For each server started by any single user, use the following formula to calculate the number of threads IQ allocates:numThreads = 60*4 + 50*(numCPUs - 4) + numConnections + 3For an 8-core system with 100 users, the numThreads is 543 threads per server.For a 64-core system with 100 users, the numThreads is 3343 threads per server.The formula also works for systems with fewer CPUs, for example, on 2-core systems.
    2. To set hard and soft limits, add the following lines to/etc/security/limits.conf:
      sybase soft nproc 7712 -- The soft limit allows for 2 servers on the 64-core system plus 1024 default. 
      sybase hard nproc 16384 -- Powers of 16 work well for kernel and engine settings. (1024 * 16) is rounded up for extra space.

      You can increase the soft limit, but the hard limit is the threshold for the value unless raised by a privileged user limit.

      To set limits for all users instead of the sybase user, replace sybase with *, for example:

      * soft nproc 7712
      * hard nproc 16384
    3. Set the process number limit in the shell script of the user who starts servers, for example:For the tcsh or C (csh) shell:limit maxproc 7712For the bash or Korn (ksh) shell:
      ulimit –u 7712
    4. Reboot your machine.
  • Workaround 2
    1. Return to Red Hat 5.x behavior by commenting out the following line in the file /etc/security/limits.d/90-nproc.conf:

      #* soft nproc 1024

    2. Reboot your machine.
Former Member
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Hi Mark,

I will check changes with OS admin and let you know result.

Thanks,