- **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 |

drives.  Therefore, the number of drives you present must be a multiple of one of these numbers.  Each object is written to a single erasure-coding set.

Minio uses the largest possible EC set size which divides into the number of drives given. For example, *18 drives* are configured as *2 sets of 9 drives*, and *24 drives* are configured as *2 sets of 12 drives*.  This is true for scenarios when running MinIO as a standalone erasure coded deployment. In [distributed setup however node (affinity)...

- 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.

				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) {

### 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
		}

			return fmt.Errorf("%s drive is already being used in another erasure deployment. (Number of drives specified: %d but the number of drives found in the %s drive's format.json: %d)",
				disks[i], len(formats), humanize.Ordinal(i+1), len(formatErasure.Erasure.Sets)*len(formatErasure.Erasure.Sets[0]))
		}
		if len(formatErasure.Erasure.Sets[0]) != setDriveCount {