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IV98427: DB2START DOESN'T SET THE KERNEL PARAMETERS(ACCEPT_LOCAL, ARP_IGNORE,RP_FILTER)ON MEMBER AUTOMATICALLY IN V10.5

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APAR status

  • Closed as program error.

Error description

  • Without these three parameters , db2ClusterPing would fail for
    some paths,also found db2start will only set those 3 parameters
    on CF, NOT on members .
    Take a trace , then check the codepath for
    SqloOSEnvConfig::setKPForMHCA
       db2stop
        db2trc on -f /tmp/file.dmp
        db2start
        db2trc off
        db2trc flw /tmp/file.dmp /tmp/file.flw
        db2trc fmt /tmp/file.dmp /tmp/flle.fmt
    280890    exit DB2 UDB oper system services
    SqloOSEnvConfig::setKPForMHCA fnc (2.3.15.1898.0)
        pid 12800 tid 140736729179904 cpid -1 node 0
        codepath = 1:7
    Here ,  trace exit of setKPForMHCA() said we are skipping the
    setting because the db2nodes.cfg indicates it is not using
    multiple adapters on the member OR this host is not a
    collocated ones.
    This is the known issue in V11.1, while the backfit of the
    V11.1 code to V10.5 is missing the node number when trying to
    autoconfigure.
    

Local fix

  • Manually set those  kernel parameters
    rp_filter = 2
    arp_ignore = 1
    accept_local = 1 (Only needed when there is collocated setup)
    We set rp_filter to 2 because this allows cross IP subnet
    communications, e.g. a packet coming out of 10.1.1.x adapter
    can be received by an adapter 10.1.2.x. mapping this to Db2, it
    means port 1 on member can send data to port 2 in CF.
    We set arp_ignore to 1 so that the netnames on members and CF
    will only respond to packets sent from other membres and CF
    defined and resolvable locally. That's one reason why we need
    to have all private adapters IPs defined in /etc/hosts.
    We set accept_local = 1 only on collocated member and CF
    configuration so that different ports on the hosts can
    communicate with each other. For RDMA ping, since we don't
    differentiate between members and CFs, we also need this.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Db2 10.5 Fix Pack 9 or higher                     *
    ****************************************************************
    

Problem conclusion

  • First fixed in Db2 10.5 Fix Pack 9
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV98427

  • Reported component name

    DB2 PURESCALE F

  • Reported component ID

    5724Y6900

  • Reported release

    A50

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-07-25

  • Closed date

    2017-09-29

  • Last modified date

    2017-09-29

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

    IV98881

Fix information

  • Fixed component name

    DB2 PURESCALE F

  • Fixed component ID

    5724Y6900

Applicable component levels

  • RA50 PSN

       UP

[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSEPGG","label":"Db2 for Linux, UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"10.5","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Document Information

Modified date:
01 August 2020