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  1. OpenShift Container Platform (OCP) Strategy
  2. OCPSTRAT-45

Add support for disk id, uuid and path to rootDeviceHints


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    • OCPSTRAT-10Install and update OpenShift on Infrastructure Providers
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      Feature Overview

      Support specifying the installation disk id, uuid or path, when installing with the Agent-based installer, Assisted Installer and the Infrastructure Operator (ACM/ZTP).

      RootDeviceHints support a number of ways to specify the disk:



      Subfield Description
      deviceName A string containing a Linux device name like /dev/vda. The hint must match the actual value exactly.
      hctl A string containing a SCSI bus address like 0:0:0:0. The hint must match the actual value exactly.
      model A string containing a vendor-specific device identifier. The hint can be a substring of the actual value.
      vendor A string containing the name of the vendor or manufacturer of the device. The hint can be a sub-string of the actual value.
      serialNumber A string containing the device serial number. The hint must match the actual value exactly.
      minSizeGigabytes An integer representing the minimum size of the device in gigabytes.
      wwn A string containing the unique storage identifier. The hint must match the actual value exactly.
      wwnWithExtension A string containing the unique storage identifier with the vendor extension appended. The hint must match the actual value exactly.
      wwnVendorExtension A string containing the unique vendor storage identifier. The hint must match the actual value exactly.
      rotational A boolean indicating whether the device should be a rotating disk (true) or not (false).

      Partners are asking to also include /dev/by-*:

      • /dev/by-id
      • /dev/by-uuid
      • /dev/by-path

      Why does the customer need this?

      Selecting the root disk by PCI path is desired by some users because:

      • deviceName is not stable and can change in unpredictable ways e.g. when a BMC virtual disk is connected
      • hctl suffers from a similar issue
      • model and vendor are not guaranteed to give a unique and predictable result
      • serialNumber and wwn are tricky to use since these methods first require a step where these are discovered.

      Selecting the root device by PCI path doesn't suffer from the drawback listed above.


      The Assisted Installer discovery (Agent), actually, discovers all these ids:

      - bootable: true
            byID: /dev/disk/by-id/wwn-0x6f4027xxxx326a9a1
            byPath: /dev/disk/by-path/pci-0000:01:00.0-scsi-0:2:0:0
            driveType: HDD
            hctl: "1:2:0:0"
            id: /dev/disk/by-id/wwn-0x6f4027xxxx326a9a1       installationEligibility:
              eligible: true
              notEligibleReasons: []
            ioPerf: {}
            model: PERC_H330_Mini
            name: sdc
            path: /dev/sdc
            serial: 6f40270XXXXX6a9a1
            sizeBytes: 959656755200 

      but cannot be selected for the installation.

            racedoro@redhat.com Ramon Acedo
            racedoro@redhat.com Ramon Acedo
            Jianwei Hou Jianwei Hou
            Stephanie Stout Stephanie Stout
            Zane Bitter Zane Bitter
            Ramon Acedo Ramon Acedo
            Dave Mulford Dave Mulford
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