Implement oboard diagnostics admin API (#9024)

- Implement a graph algorithm to test network bandwidth from every 
  node to every other node
- Saturate any network bandwidth adaptively, accounting for slow 
  and fast network capacity
- Implement parallel drive OBD tests
- Implement a paging mechanism for OBD test to provide periodic updates to client
- Implement Sys, Process, Host, Mem OBD Infos

pkg/madmin/obd_other.go

@@ -0,0 +1,33 @@
+// +build !freebsd
+
+/*
+ * MinIO Cloud Storage, (C) 2020 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 (
+	diskhw "github.com/shirou/gopsutil/disk"
+)
+
+// ServerDiskHwOBDInfo - Includes usage counters, disk counters and partitions
+type ServerDiskHwOBDInfo struct {
+	Addr       string                           `json:"addr"`
+	Usage      []*diskhw.UsageStat              `json:"usages,omitempty"`
+	Partitions []diskhw.PartitionStat           `json:"partitions,omitempty"`
+	Counters   map[string]diskhw.IOCountersStat `json:"counters,omitempty"`
+	Error      string                           `json:"error,omitempty"`
+}