- **MinIO creates erasure-coding sets of _2_ to _16_ drives per set.  The number of drives you provide in total must be a multiple of one of those numbers.**
- **MinIO chooses the largest EC set size which divides into the total number of drives or total number of nodes given - making sure to keep the uniform distribution i.e each node participates equal number of drives per set**.

two parity drives, 100 MiB file takes only approximately 114 MiB.

Below is a list of data/parity drives and corresponding _approximate_ storage space usage on a 16 drive MinIO deployment. The field _storage
usage ratio_ is simply the drive space used by the file after erasure-encoding, divided by actual file size.

| Total Drives (N) | Data Drives (D) | Parity Drives (P) | Storage Usage Ratio |

- We limited the number of drives to 16 for erasure set because, erasure code shards more than 16 can become chatty and do not have any performance advantages. Additionally since 16 drive erasure set gives you tolerance of 8 drives per object by default which is plenty in any practical scenario.

		"Count of offline drives in the cluster")
	healthDrivesOnlineCountMD = NewGaugeMD(healthDrivesOnlineCount,
		"Count of online drives in the cluster")
	healthDrivesCountMD = NewGaugeMD(healthDrivesCount,
		"Count of all drives in the cluster")
)

// loadClusterHealthDriveMetrics - `MetricsLoaderFn` for cluster storage drive metrics
// such as online, offline and total drives.

				Deleted: v.Created,
			})
		}
		return true
	})

	return buckets, nil
}

func cloneDrives(drives map[string]StorageAPI) []StorageAPI {
	copyDrives := make([]StorageAPI, 0, len(drives))
	for _, drive := range drives {
		copyDrives = append(copyDrives, drive)
	}
	return copyDrives
}

func getBucketInfoLocal(ctx context.Context, bucket string, opts BucketOptions) (BucketInfo, error) {

If one or more drives are offline at the start of a PutObject or NewMultipartUpload operation the object will have additional data
protection bits added automatically to provide the regular safety for these objects up to 50% of the number of drives.
This will allow normal write operations to take place on systems that exceed the write tolerance.

### 1.2 Host Multiple Tenants on Multiple Drives (Erasure Code)

Use the following commands to host 3 tenants on multiple drives:

```sh
minio server --address :9001 /disk{1...4}/data/tenant1
minio server --address :9002 /disk{1...4}/data/tenant2
minio server --address :9003 /disk{1...4}/data/tenant3
```

| Minimum number of drives per server when server count is 1      | 02            |
| Minimum number of drives per server when server count is 2 or 3 | 01            |
| Minimum number of drives per server when server count is 4      | 01            |
| Maximum number of drives per server                             | no-limit      |
| Read quorum                                                     | N/2           |

	if ssParity > 0 && rrsParity > 0 {
		if ssParity < rrsParity {
			return fmt.Errorf("Standard storage class parity drives %d should be greater than or equal to Reduced redundancy storage class parity drives %d", ssParity, rrsParity)
		}
	}
	return nil
}

// GetParityForSC - Returns the data and parity drive count based on storage class
// If storage class is set using the env vars MINIO_STORAGE_CLASS_RRS and

	if err == nil {
		return storageDisks, format, nil
	}

	tries++ // tried already once

	// Wait on each try for an update.
	ticker := time.NewTicker(1 * time.Second)
	defer ticker.Stop()

	for {
		// Only log once every 10 iterations, then reset the tries count.
		verbose = tries >= 10
		if verbose {
			tries = 1
		}