Obtain a by-id symlink of a storage device

You can start using a storage device only after a corresponding Machine becomes ready and accessible. Thus, KaaSCephCluster can be created only after all machines receive the status.providerStatus.hardware.storage configuration containing all required device by-id symlinks.

To obtain a device by-id symlink:

1. Verify that the Machine is Ready:

   kubectl -n <managedClusterProject> get machine <machineName> -o jsonpath='{.status.phase}{"\n"}'
   

   Substitute <managedClusterProject> with the cluster namespace and <machineName> with the machine name.

2. Obtain storage details for the Machine:

   kubectl -n <managedClusterProject> get machine <machineName> -o yaml
   

   Output example:

   status:
     providerStatus:
       hardware:
         storage:
         - byID: /dev/disk/by-id/wwn-0x05ad99618d66a21f
           byIDs:
           - /dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_05ad99618d66a21f
           - /dev/disk/by-id/scsi-305ad99618d66a21f
           - /dev/disk/by-id/scsi-SQEMU_QEMU_HARDDISK_05ad99618d66a21f
           - /dev/disk/by-id/wwn-0x05ad99618d66a21f
           byPath: /dev/disk/by-path/pci-0000:00:05.0-scsi-0:0:0:0
           byPaths:
           - /dev/disk/by-path/pci-0000:00:05.0-scsi-0:0:0:0
           name: /dev/sda
           serialNumber: 05ad99618d66a21f
           size: 61
           type: hdd
         - byID: /dev/disk/by-id/wwn-0x26d546263bd312b8
           byIDs:
           - /dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_26d546263bd312b8
           - /dev/disk/by-id/scsi-326d546263bd312b8
           - /dev/disk/by-id/scsi-SQEMU_QEMU_HARDDISK_26d546263bd312b8
           - /dev/disk/by-id/wwn-0x26d546263bd312b8
           byPath: /dev/disk/by-path/pci-0000:00:05.0-scsi-0:0:0:2
           byPaths:
           - /dev/disk/by-path/pci-0000:00:05.0-scsi-0:0:0:2
           name: /dev/sdb
           serialNumber: 26d546263bd312b8
           size: 32
           type: hdd
         - byID: /dev/disk/by-id/wwn-0x2e52abb48862dbdc
           byIDs:
           - /dev/disk/by-id/lvm-pv-uuid-MncrcO-6cel-0QsB-IKaY-e8UK-6gDy-k2hOtf
           - /dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_2e52abb48862dbdc
           - /dev/disk/by-id/scsi-32e52abb48862dbdc
           - /dev/disk/by-id/scsi-SQEMU_QEMU_HARDDISK_2e52abb48862dbdc
           - /dev/disk/by-id/wwn-0x2e52abb48862dbdc
           byPath: /dev/disk/by-path/pci-0000:00:05.0-scsi-0:0:0:1
           byPaths:
           - /dev/disk/by-path/pci-0000:00:05.0-scsi-0:0:0:1
           name: /dev/sdc
           serialNumber: 2e52abb48862dbdc
           size: 61
           type: hdd
   

3. Obtain the item from the byIDs list from the status.providerStatus.hardware.storage section that contains serialNumber and does not contain wwn as a bus ID.

   In the example above, for the disk with the /dev/sdc name, you can use the /dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_2e52abb48862dbdc symlink as a persistent identifier of the storage device because it contains the 2e52abb48862dbdc serial number and does not contain wwn.

   Note

   Do not rely on the byID field only. This field may contain a /dev/disk/by-id/wwn symlink that cannot be considered a persistent identifier of a storage device.

See also

• Migrate Ceph cluster to address storage devices using by-id

• Container Cloud documentation: Addressing storage devices