[Bug 1559193] Comment bridged from LTC Bugzilla

[bugproxy]

------- Comment From thorsten.diehl at de.ibm.com 2016-04-01 09:19 EDT-------
Obviously some of the changes are breaking the zfcp installation now. Installer (no DASDs, but zfcp devices) dropped into the disk-detect menu, without asking for zfcp device initialization. See LTC bug 139913 which is being mirrored.

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Title:
  disk-detect/s390-dasd/s390-zfcp: Restructure installer and put DASD
  and FCP configuration into disk detection

Status in hw-detect package in Ubuntu:
  Invalid
Status in s390-dasd package in Ubuntu:
  Invalid
Status in s390-zfcp package in Ubuntu:
  Fix Released
Status in hw-detect package in Debian:
  New
Status in s390-dasd package in Debian:
  New
Status in s390-zfcp package in Debian:
  New

Bug description:
  == Comment: #1 - Hendrik Brueckner <brueckner at de.ibm.com> - 2016-03-18 09:23:45 ==
  On Linux on z Systems, there are two major disk storage environments,
  the direct-attached storage disk (DASD) and SCSI over Fibre-Channel.

  There are the s390-dasd and s390-zfcp d-i modules to configure and
  enable DASDs and FCP devices.  Note that on s390x, disks are not
  available by default to Linux and must be enabled in advance.

  The s390-dasd and s390-zfcp both provide the harddrive-detection
  dependency and, thus, each could fulfill the dependency to silenty
  ignore the other.  That behavior does not allow to mix DASDs and
  SCSI disk on single installation (except you call both manually,
  for example, in the expert mode).

  To improve and provide a "guided" flow, I have split the harddrive
  detection dependency for s390-dasd and s390-zfcp as follows:

  - s390-dasd provides harddrive-detection-dasd
  - s390-zfcp provides harddrive-detection-zfcp

  disk-detect depends on
    -> harddrive-detection-dasd
    -> harddrive-detection-zfcp

  and continues to provide the harddrive-detection.

  With this split, the guided installation will install disk-detect to
  solve the harddrive-detection dependency.  In turn, disk-detect will
  then rely on the s390-dasd and s390-zfcp d-i modules to provide DASD
  and FC-attached SCSI disks.  If both modules fail, the user perceives
  the default disk-detect behavior, for example, users might configure
  iSCSI.

  The other nice benefit of this dependency split is the seamlessly
  enablement of multipath with disk-detect (through preseeding).
  For s390, multipathing should be always considered when SCSI is used.
  I probably will extend the s390-zfcp module to set disk-detect's
  multipath debconf variable for usability.

  
  There are already Debian bug reports with patches to provide this solution:

  disk-detect: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=818586
  s390-dasd: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=818591
  s390-zfcp: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=818592

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