Add large bucket support for erasure coded backend (#5160)

This PR implements an object layer which
combines input erasure sets of XL layers
into a unified namespace.

This object layer extends the existing
erasure coded implementation, it is assumed
in this design that providing > 16 disks is
a static configuration as well i.e if you started
the setup with 32 disks with 4 sets 8 disks per
pack then you would need to provide 4 sets always.

Some design details and restrictions:

- Objects are distributed using consistent ordering
  to a unique erasure coded layer.
- Each pack has its own dsync so locks are synchronized
  properly at pack (erasure layer).
- Each pack still has a maximum of 16 disks
  requirement, you can start with multiple
  such sets statically.
- Static sets set of disks and cannot be
  changed, there is no elastic expansion allowed.
- Static sets set of disks and cannot be
  changed, there is no elastic removal allowed.
- ListObjects() across sets can be noticeably
  slower since List happens on all servers,
  and is merged at this sets layer.

Fixes #5465
Fixes #5464
Fixes #5461
Fixes #5460
Fixes #5459
Fixes #5458
Fixes #5460
Fixes #5488
Fixes #5489
Fixes #5497
Fixes #5496

pkg/madmin/heal-commands_test.go

@@ -0,0 +1,73 @@
+/*
+ * Minio Cloud Storage, (C) 2018 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package madmin
+
+import (
+	"testing"
+)
+
+// Tests heal drives missing and offline counts.
+func TestHealDriveCounts(t *testing.T) {
+	rs := HealResultItem{}
+	rs.Before.Drives = make([]HealDriveInfo, 20)
+	rs.After.Drives = make([]HealDriveInfo, 20)
+	for i := range rs.Before.Drives {
+		if i < 4 {
+			rs.Before.Drives[i] = HealDriveInfo{State: DriveStateMissing}
+			rs.After.Drives[i] = HealDriveInfo{State: DriveStateMissing}
+		} else if i > 4 && i < 15 {
+			rs.Before.Drives[i] = HealDriveInfo{State: DriveStateOffline}
+			rs.After.Drives[i] = HealDriveInfo{State: DriveStateOffline}
+		} else if i > 15 {
+			rs.Before.Drives[i] = HealDriveInfo{State: DriveStateCorrupt}
+			rs.After.Drives[i] = HealDriveInfo{State: DriveStateCorrupt}
+		} else {
+			rs.Before.Drives[i] = HealDriveInfo{State: DriveStateOk}
+			rs.After.Drives[i] = HealDriveInfo{State: DriveStateOk}
+		}
+	}
+
+	i, j := rs.GetOnlineCounts()
+	if i > 2 {
+		t.Errorf("Expected '2', got %d before online disks", i)
+	}
+	if j > 2 {
+		t.Errorf("Expected '2', got %d after online disks", j)
+	}
+	i, j = rs.GetOfflineCounts()
+	if i > 10 {
+		t.Errorf("Expected '10', got %d before offline disks", i)
+	}
+	if j > 10 {
+		t.Errorf("Expected '10', got %d after offline disks", j)
+	}
+	i, j = rs.GetCorruptedCounts()
+	if i > 4 {
+		t.Errorf("Expected '4', got %d before corrupted disks", i)
+	}
+	if j > 4 {
+		t.Errorf("Expected '4', got %d after corrupted disks", j)
+	}
+	i, j = rs.GetMissingCounts()
+	if i > 4 {
+		t.Errorf("Expected '4', got %d before missing disks", i)
+	}
+	if j > 4 {
+		t.Errorf("Expected '4', got %d after missing disks", i)
+	}
+}