"Setting the DASD online with discipline DIAG failed with rc=-95" for random devices at startup on RHEL on IBM Z

Solution Verified - Updated -


During system startup a random set od DASD drives fail to initialize with following messages printed for those devices:

kernel: 0.0.0101: A 64-bit DIAG call failed
kernel: dasd: 0.0.0101 Setting the DASD online with discipline DIAG failed with rc=-95


  • Red Hat Enterprise Linux 7 on IBM Z (mainframe)
  • kernel-3.10.0-1127.4.el7.s390x or later
  • DASD storage and driver presence
  • use_diag flag is set (use_diag=1)

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