In 12 drive example above, with MinIO server running in the default configuration, you can lose any of the six drives and still reconstruct the data reliably from the remaining drives.

## Why is Erasure Code useful?

| `minio_system_drive_used_inodes`               | Total used inodes on a drive. <br><br>Type: gauge                                       | `drive`, `set_index`, `drive_index`, `pool_index`, `server`        |

          "legendFormat": "Free [{{drive}}]",
          "refId": "C"
        }
      ],
      "title": "Drive Usage",
      "type": "timeseries"
    },
    {
      "datasource": {
        "type": "prometheus",
        "uid": "${DS_PROMETHEUS}"
      },
      "description": "",
      "fieldConfig": {
        "defaults": {
          "color": {
            "mode": "palette-classic"
          },

## Storage usage

The selection of varying data and parity drives has a direct impact on the drive space usage. With storage class, you can optimize for high
redundancy or better drive space utilization.

To get an idea of how various combinations of data and parity drives affect the storage usage, let’s take an example of a 100 MiB file stored

				if deploymentID != "" {
					newFormat.ID = deploymentID
				}
				drive := pool.Endpoints[i*setDriveCount+j]
				fmtBytes, err := json.Marshal(newFormat)
				if err != nil {
					//nolint:gocritic
					log.Fatalf("failed to marshal format.json for %s: %v", drive.String(), err)
				}
				fmtJSON := filepath.Join(drive.Host, drive.Path, minioMetaBucket, "format.json")
				embedFileInZip(fmtZipW, fmtJSON, fmtBytes, 0o600)

| `minio_node_drive_total_inodes`      | Total inodes on a drive.                                 |
| `minio_node_drive_used_inodes`       | Total inodes used on a drive.                            |
| `minio_node_drive_reads_per_sec`     | Reads per second on a drive.                             |
| `minio_node_drive_reads_kb_per_sec`  | Kilobytes read per second on a drive.                    |

	if err != nil {
		if errors.Is(err, errDriveIsRoot) {
			// This is a root drive, ignore and move on
			return nil
		}
		if !errors.Is(err, errUnformattedDisk) {
			return err
		}
	}

	// Prevent parallel erasure set healing
	locker := z.NewNSLock(minioMetaBucket, fmt.Sprintf("new-drive-healing/%d/%d", poolIdx, setIdx))
	lkctx, err := locker.GetLock(ctx, newDiskHealingTimeout)
	if err != nil {

			}
		}
	case config.DriveSubSys:
		driveConfig, err := drive.LookupConfig(s[config.DriveSubSys][config.Default])
		if err != nil {
			configLogIf(ctx, fmt.Errorf("Unable to load drive config: %w", err))
		} else {
			if err = globalDriveConfig.Update(driveConfig); err != nil {
				configLogIf(ctx, fmt.Errorf("Unable to update drive config: %v", err))
			}
		}
	case config.BrowserSubSys:

		if err != nil {
			return nil, nil, fmt.Errorf("Drive %s: %w", export, err)
		}
		// Migrate successful v1 => v2, proceed to v2 => v3
		version = formatErasureVersionV2
		fallthrough
	case formatErasureVersionV2:
		formatData, err = formatErasureMigrateV2ToV3(formatData, export, version)
		if err != nil {
			return nil, nil, fmt.Errorf("Drive %s: %w", export, err)
		}

		errs, fi, false, bucket, object, madmin.HealDeepScan)

	for diskIndex, disk := range erasureDisks {
		if diskIndex == 0 && disk != nil {
			t.Errorf("Drive not filtered as expected, drive: %d", diskIndex)
		}
		if diskIndex != 0 && disk == nil {
			t.Errorf("Drive erroneously filtered, driveIndex: %d", diskIndex)
		}
	}
	partsMetadata[0] = partsMetadataBackup // Revert before going to the next test