pick disks which are common maximally used (#10600)

further optimization to ensure that good disks
are always used for listing, other than healing
we only use disks that are maximally used.

pkg/disk/stat_netbsd.go

@@ -19,6 +19,8 @@
 package disk
 
 import (
+	"fmt"
+
 	"golang.org/x/sys/unix"
 )
 
@@ -36,5 +38,9 @@ func GetInfo(path string) (info Info, err error) {
 		Ffree:  uint64(s.Ffree),
 		FSType: string(s.Fstypename[:]),
 	}
+	if info.Free > info.Total {
+		return info, fmt.Errorf("detected free space (%d) > total disk space (%d), fs corruption at (%s). please run 'fsck'", info.Free, info.Total, path)
+	}
+	info.Used = info.Total - info.Free
 	return info, nil
 }