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Db2 11.5 on RHEL Guest on KVM

  • 1.  Db2 11.5 on RHEL Guest on KVM

    Posted Tue June 23, 2020 09:44 AM
    I installed DB2 luW 11.5 on RHEL (7.5) running on KVM ( RHEL 8.2) and facing issues with operations. The install itself is going through without any issues, and I am able to create a DB2 Instance. First explicit connection to the instance with password locks up the server / instance with db2sysc hitting 100% CPU. There is nothing on the diaglog (with diaglevel 4) or any other linux logs. Below are the sequence of steps.

    a) Installed all necessary pre-requisites - basically just 32 bit pam and libstdc++ libraries
    b) Installed db2 data server - no purescale
    c) create ese db2inst1 instance (no database yet)
    d) "Db2 attach to db2inst1" - works perfectly.
    e) "db2 attach to db2inst1 user db2inst1 using xxxxxx" - hangs indefinitely

    Local users, no fancy ldap, sssd etc. No SSL. My Host OS is RHEL 8.2 with all the latest updates. I tried both RHEL 7 guests and CentOS 7 Guests with the same result. I tried RHEL 8.2 guest and direct install on the 8.2 host as well with the same result.

    My hunch is, there is something on the new host kernel (4.18) that is making db2 slip, though running on a supported guest version. Any thoughts on settings that can make this guest work ?

    Regards
    Vijay

    ------------------------------
    Vijay Shankar Arunachalam
    ------------------------------

    #Db2
    #Db2EarlyAccessProgram(EAP)Forum


  • 2.  RE: Db2 11.5 on RHEL Guest on KVM

    Posted Wed June 24, 2020 10:34 AM
    Edited by System Admin Fri January 20, 2023 04:33 PM

    Can you please provide the detail on the level of the Db2 EAP that is being used? We need more detail to understand where Db2 is spinning, (Stack, vmstat).

    Also please note that RHEL 8 support is on next release of Db2 which is going to be available next week.



    ------------------------------
    MOJGAN SAMIFANNI
    ------------------------------

    Original Message


  • 3.  RE: Db2 11.5 on RHEL Guest on KVM

    Posted Wed June 24, 2020 11:26 AM
    I was still using the vanilla 11.5.0, i did  not install the EAP binary. Let me try the new binary and see if this goes away. If I am still seeing this issue let me pull out the logs.

    RHel 8 support on the June release is great news.  I may just be able to use it rather than playing around with a base version. I will try the EAP nevertheless.

    Regards
    Vijay

    ------------------------------
    Vijay Shankar Arunachalam
    ------------------------------

    Original Message


  • 4.  RE: Db2 11.5 on RHEL Guest on KVM

    Posted Thu June 25, 2020 04:20 AM
      |   view attached
    Well, I created a new guest with DB2 8.1 and Installed the EAP 156 [ Build s2004181500(EAP56) ]. The result was still the same. I am attaching a zip file with the below information

    a) A stack directory with the db2pd -stack all output files
    b) Db2 Installation Logs
    c) A xml file with KVM definition
    d) vmstat output during the failure and also a screesnot of top
    e) db2diag log with diaglevel 4

    The host is at 8.2, with all the latest updates till yesterday.

    Thank You
    Vijay

    ------------------------------
    Vijay Shankar Arunachalam
    ------------------------------

    Attachment(s)

    zip
    db2-eap-rhel-kvm-issues-06-25-2020.zip   121 KB 1 version
    Original Message


  • 5.  RE: Db2 11.5 on RHEL Guest on KVM

    Posted Fri June 26, 2020 10:07 AM
    Thank you Vijay will get back to you as soon as we have reviewed the diagnostics that you sent.

    ------------------------------
    MOJGAN SAMIFANNI
    ------------------------------

    Original Message


  • 6.  RE: Db2 11.5 on RHEL Guest on KVM

    Posted Mon June 29, 2020 01:30 AM
    Thanks for the update Mojgan,

    Couple of additional updates:

    a)  This issue goes off if i exclude installation of gskit during installation. It comes back, if I install gskit externally and enable it. I tried gskit 8.0.55.15, 64 bit linux.  I have to keep the crypt_not_installed file under the bin directory to keep DB2 functioning without crypto.
    b) The issue disappears if i use QEMU hypervisor without KVM.  This is not feasible though as it s very slow due to lack of hardware virtualization

    Underlying host hardware is AMD Ryzen. I have attached the CPU config for the host and the guest.

    Regards
    Vijay

    ------------------------------
    Vijay Shankar Arunachalam
    ------------------------------

    Attachment(s)

    txt
    lscpu-host.txt   1 KB 1 version
    txt
    lscpu-kvm-guest.txt   1 KB 1 version
    Original Message


  • 7.  RE: Db2 11.5 on RHEL Guest on KVM

    Posted Thu July 09, 2020 02:05 AM
    Mojgan

    Any luck with this ?

    Regards
    Vijay

    ------------------------------
    Vijay Shankar Arunachalam
    ------------------------------

    Original Message


  • 8.  RE: Db2 11.5 on RHEL Guest on KVM

    Posted Thu July 16, 2020 10:51 AM
    GSKit has a lot that happens during initialization to ensure that it's random number generator is initialized with truly random input.  Sometimes VMs can cause problems because they lack some of the randomness GSKit is looking at.

    I do see GSKit in one of the stacks, although it seems to be truncated and only the top few functions are included, so I can't tell exactly where it's being initiated from within Db2.

    You mentioned being able to reproduce this directly on the host, outside of a VM.  That might help eliminate certain paths of investigation.  Is it possible for you to gather the stacks and such from that install?

    ------------------------------
    GREG STAGER
    ------------------------------

    Original Message


  • 9.  RE: Db2 11.5 on RHEL Guest on KVM

    Posted Fri July 17, 2020 03:14 AM
    Thanks for checking this. Let me install the EAP on the host machine and give you the details

    Regards
    Vijay

    ------------------------------
    Vijay Shankar Arunachalam
    ------------------------------

    Original Message


  • 10.  RE: Db2 11.5 on RHEL Guest on KVM

    Posted Fri July 17, 2020 09:42 AM
    Now that 11.5.4 is out, you may want to just use the official modpack instead of an EAP build.  Also if you can get a repro with the official modpack, and on the host, you may get better support opening a case.

    One other thing you could try is to force GSKit to use the random number generator of the CPU.

    Add the following to the end of the file ~/sqllib/lib64/gskit/C/icclib/ICCSIG.txt

    ICC_TRNG=TRNG_ALT3

    then
    db2stop/db2start

    Thanks,

    Greg

    ------------------------------
    GREG STAGER
    ------------------------------

    Original Message


  • 11.  RE: Db2 11.5 on RHEL Guest on KVM

    Posted Mon July 20, 2020 05:57 AM
    Greg

    Couple of updates.

    a) The update to the ICCSIG.txt to make gskit use the random number generator of the CPU worked for me and the instance no longer hangs up with gskit enabled. I tested this on both the older 11.5.0 and 11.5.4 versions and it works without any issues. I had to update both 32bit and 64bit gskit installs to get this working.

    b)  Without this update, the issue persists. Since we wanted to test, i checked this on the host as well without any virtualization. This also went off with updates to the ICCSIG.txt file. I have attached the stack trace for the host, if you want to take a look at it and see if something looks fishy.

    One question though - will this change impact performance ? Do you have any insight into why this fails without this flag ?

    Regards
    Vijay 

    ------------------------------
    Vijay Shankar Arunachalam
    ------------------------------

    Attachment(s)

    txt
    host_v_11.5.4_vmstat.txt   12 KB 1 version
    log
    host_v_11.5.4_db2diag.log   353 KB 1 version
    zip
    host_v_11.5.4_stack-trace.zip   74 KB 1 version
    Original Message


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