sap_storage_setup: Add exact size disk check on top of approximate check

[marcelmamula]

Problem:

• Current disk assignment works on approximate validation with (disk_size_gb-8) <= fs.disk_size <= (disk_size_gb+8) which invalidates this role when filesystems with less than 8 GB differences are used.

• Current loop will pick first found, invalidating correct entries, causing cascading failure during LV creation because of device: ""

Example:

Disks with sizes 15, 20 and 25 are used.

/hana/shared will never be loaded, because /hana/log will find 25GB disk, use it and /hana/shared would be left without entry in following list of disks.volume_map

    sap_storage_setup_definition: [
      {
        "disk_size": 15,
        "filesystem_type": "xfs",
        "mountpoint": "/hana/data",
        "name": "hana_data"
      },
      {
        "disk_size": 20,
        "filesystem_type": "xfs",
        "mountpoint": "/hana/log",
        "name": "hana_log"
      },
      {
        "disk_size": 25,
        "filesystem_type": "xfs",
        "mountpoint": "/hana/shared",
        "name": "hana_shared"
      }
    ]

Solution:

Add initial check for exact sizes, followed up by original approximate check which will run empty if all disk sizes were correctly found during first pass.

• First pass: disk_size_gb == fs.disk_size
• Second pass: (disk_size_gb-8) <= fs.disk_size <= (disk_size_gb+8)

[ja9fuchs]

lgtm, nice catch for tiny disk sizing
👍