fix: The free disk size and percentage are quite different from the output of df -h. (#6550)

* fix: record and delete bucket metrics after inactive

* feat: match available disk size with system cmd `dh -h`

* feat: move temp test to unmaintained/

---------

Co-authored-by: XYZ <XYZ>

unmaintained/disk/disk_status.go

@@ -0,0 +1,57 @@
+//go:build !windows && !openbsd && !netbsd && !plan9 && !solaris
+// +build !windows,!openbsd,!netbsd,!plan9,!solaris
+
+package main
+
+import (
+	"log"
+	"syscall"
+)
+
+// go run unmaintained/disk/disk_status.go
+
+type DiskStatus struct {
+	Dir         string  `protobuf:"bytes,1,opt,name=dir,proto3" json:"dir,omitempty"`
+	All         uint64  `protobuf:"varint,2,opt,name=all,proto3" json:"all,omitempty"`
+	Used        uint64  `protobuf:"varint,3,opt,name=used,proto3" json:"used,omitempty"`
+	Free        uint64  `protobuf:"varint,4,opt,name=free,proto3" json:"free,omitempty"`
+	PercentFree float32 `protobuf:"fixed32,5,opt,name=percent_free,json=percentFree,proto3" json:"percent_free,omitempty"`
+	PercentUsed float32 `protobuf:"fixed32,6,opt,name=percent_used,json=percentUsed,proto3" json:"percent_used,omitempty"`
+	DiskType    string  `protobuf:"bytes,7,opt,name=disk_type,json=diskType,proto3" json:"disk_type,omitempty"`
+
+	// new fields about avail blocks
+	Avail        uint64  `protobuf:"varint,4,opt,name=avail,proto3" json:"avail,omitempty"`
+	PercentAvail float32 `protobuf:"fixed32,5,opt,name=percent_avail,json=percentAvail,proto3" json:"percent_avail,omitempty"`
+}
+
+func main() {
+	dirs := []string{"/mnt/sdb", "/mnt/sdc", "/mnt/sdd", "/mnt/sde", "/mnt/sdf", "/mnt/sdg", "/mnt/sdh", "/mnt/sdi", "/mnt/sdj"}
+	// dirs := []string{"/mnt/sdb"}
+	for _, dir := range dirs {
+		disk := &DiskStatus{Dir: dir}
+		fillInDiskStatus(disk)
+
+		// bytes, _ := json.Marshal(disk)
+		// log.Printf("disk status %s", bytes)
+		log.Printf("disk: %s avail: %f free: %f", disk.Dir, disk.PercentAvail, disk.PercentFree)
+	}
+}
+
+func fillInDiskStatus(disk *DiskStatus) {
+	fs := syscall.Statfs_t{}
+	err := syscall.Statfs(disk.Dir, &fs)
+	if err != nil {
+		return
+	}
+
+	disk.All = fs.Blocks * uint64(fs.Bsize)
+	disk.Free = fs.Bfree * uint64(fs.Bsize)
+	disk.Used = disk.All - disk.Free
+	disk.PercentFree = float32((float64(disk.Free) / float64(disk.All)) * 100)
+	disk.PercentUsed = float32((float64(disk.Used) / float64(disk.All)) * 100)
+
+	// avail blocks
+	disk.Avail = fs.Bavail * uint64(fs.Bsize)
+	disk.PercentAvail = float32((float64(disk.Avail) / float64(disk.All)) * 100)
+	return
+}

weed/stats/disk_supported.go

@@ -16,7 +16,11 @@ func fillInDiskStatus(disk *volume_server_pb.DiskStatus) {
 		return
 	}
 	disk.All = fs.Blocks * uint64(fs.Bsize)
-	disk.Free = fs.Bfree * uint64(fs.Bsize)
+	// https://man7.org/linux/man-pages/man3/statvfs.3.html
+	// fs.Bfree: Number of free blocks
+	// fs.Bavail: Number of free blocks for unprivileged users
+	// disk.Free = fs.Bfree * uint64(fs.Bsize)
+	disk.Free = fs.Bavail * uint64(fs.Bsize)
 	disk.Used = disk.All - disk.Free
 	disk.PercentFree = float32((float64(disk.Free) / float64(disk.All)) * 100)
 	disk.PercentUsed = float32((float64(disk.Used) / float64(disk.All)) * 100)