IJ21542: DB2PREREQCHECK SHOULD NOT CHECK MODPROBE FILE WHEN USING MELLANOX CX-4 IB/ROCE CARD ON LINUX PLATFORM

Db2 Version 11.1 Mod 4 Fix Pack 6 for Linux, UNIX, and Windows
Db2 Version 11.1 Mod 4 Fix Pack 6 for Linux, UNIX, and Windows

APAR status

• Closed as fixed if next.

Error description

• As of Mellanox ConnectX-4 IB and Roce HCA, there are no
  mlx4_core and mlx4_en module anymore, while , the Installation
  for V11.1 and V11.5 GA version still check whether options
  mlx4_core log_mtts_per_seg=7 in /etc/modprobe.d/modprobe.conf ,
  this is wrong , db2prereqcheck should not check this .
  
  For customer who use Mellanox ConnectX-4 HCA driver , may follow
  the topic "Preinstallation checklist for Db2 pureScale Feature
  (Linux) " in KC to configure the step 4   ,while cannot find the
  path <host-name>/sys/module/mlx4_core/parameters when go to
  check if it takes effect  , KC needs to rectify also defect
  should open to remove the pre-check of file modprobe
  
  https://www.ibm.com/support/knowledgecenter/en/SSEPGG_11.1.0/com
  .ibm.db2.luw.qb.server.doc/doc/r0057204.html
  Increase the Mellanox HCA driver mlx4_core parameter
  log_mtts_per_seg value from 3 (the default) to 7 on the host
  where the cluster caching facility (CF) resides. To increase the
  size, issue this command as root:
  
      Starting from SLES 12 and RHEL 6.10, these module options
  must be built into the initial image used by the kernel during
  boot:
  
      echo "options mlx4_core log_mtts_per_seg=7" >>
  /etc/modprobe.d/modprobe.conf
      dracut -f
      Copy
  
      On SLES 11:
  
      echo "options mlx4_core log_mtts_per_seg=7" >>
  /etc/modprobe.conf.local
      Copy
  
      On RHEL 6:
  
      echo "options mlx4_core log_mtts_per_seg=7" >>
  /etc/modprobe.d/modprobe.conf
      Copy
  
  For this change to take effect, you must reboot the server. To
  check whether your change is effective on the module, issue this
  command:
  
  <host-name>/sys/module/mlx4_core/parameters # cat
  /sys/module/mlx4_core/parameters/log_mtts_per_seg
  7
  

Local fix

• We need to create this file /etc/modprobe.d/modprobe.conf for
  RHEL( or /etc/modprobe.conf.local for SLES)and put the entry in
  the file "options mlx4_core log_mtts_per_seg=7"  on each node to
  bypass installation
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Client that use ConnectX-4 on Linux                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * We need to create this file /etc/modprobe.d/modprobe.conf    *
  * for RHEL( /etc/modprobe.conf.local for SLES)and put the      *
  * entry in the file "options mlx4_core log_mtts_per_seg=7"  on *
  * each node to bypass installation.                            *
  ****************************************************************
  

Problem conclusion

Temporary fix

Comments

APAR Information

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

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

Fix information

Applicable component levels

• RB10 PSN

     UP

• RB10 PSY

     UP

• RB50 PSN

     UP

• RB50 PSY

     UP