Fix: Filtering out ramdisks in diskio metricset

CHANGELOG.next.asciidoc

@@ -146,6 +146,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Reuse connections in PostgreSQL metricsets. {issue}12504[12504] {pull}12603[12603]
 - PdhExpandWildCardPathW will not expand counter paths in 32 bit windows systems, workaround will use a different function.{issue}12590[12590]{pull}12622[12622]
 - In the elasticsearch/node_stats metricset, if xpack is enabled, make parsing of ES node load average optional as ES on Windows doesn't report load average. {pull}12866[12866]
+- Ramdisk is not filtered out when collecting disk performance counters in diskio metricset {issue}12814[12814] {pull}12829[12829]
 
 *Packetbeat*
 

metricbeat/module/system/diskio/diskstat_windows_helper.go

@@ -20,9 +20,12 @@
 package diskio
 
 import (
+	"strings"
 	"syscall"
 	"unsafe"
 
+	windows2 "golang.org/x/sys/windows"
+
 	"github.com/elastic/beats/libbeat/logp"
 
 	"github.com/pkg/errors"
@@ -86,7 +89,8 @@ func ioCounters(names ...string) (map[string]disk.IOCountersStat, error) {
 		var counter diskPerformance
 		err = ioCounter(drive.UNCPath, &counter)
 		if err != nil {
-			return nil, err
+			logp.Err("Could not return any performance counter values for %s .Error: %v", drive.UNCPath, err)
+			continue
 		}
 		ret[drive.Name] = disk.IOCountersStat{
 			Name:       drive.Name,
@@ -220,9 +224,40 @@ func isValidLogicalDrive(path string) bool {
 	}
 	ret, _, err := syscall.Syscall(procGetDriveTypeW.Addr(), 1, uintptr(unsafe.Pointer(utfPath)), 0, 0)
 
-	//DRIVE_NO_ROOT_DIR = 1 DRIVE_CDROM = 5
-	if ret == 1 || ret == 5 || err != errorSuccess {
+	//DRIVE_NO_ROOT_DIR = 1 DRIVE_CDROM = 5 DRIVE_UNKNOWN = 0 DRIVE_RAMDISK = 6
+	if ret == 1 || ret == 5 || ret == 0 || ret == 6 || err != errorSuccess {
+		return false
+	}
+
+	//check for ramdisk label as the drive type is fixed in this case
+	volumeLabel, err := GetVolumeLabel(utfPath)
+	if err != nil {
+		return false
+	}
+	if strings.ToLower(volumeLabel) == "ramdisk" {
 		return false
 	}
 	return true
 }
+
+// GetVolumeLabel function will retrieve the volume label
+func GetVolumeLabel(path *uint16) (string, error) {
+	lpVolumeNameBuffer := make([]uint16, 256)
+	lpVolumeSerialNumber := uint32(0)
+	lpMaximumComponentLength := uint32(0)
+	lpFileSystemFlags := uint32(0)
+	lpFileSystemNameBuffer := make([]uint16, 256)
+	err := windows2.GetVolumeInformation(
+		path,
+		&lpVolumeNameBuffer[0],
+		uint32(len(lpVolumeNameBuffer)),
+		&lpVolumeSerialNumber,
+		&lpMaximumComponentLength,
+		&lpFileSystemFlags,
+		&lpFileSystemNameBuffer[0],
+		uint32(len(lpFileSystemNameBuffer)))
+	if err != nil {
+		return "", err
+	}
+	return syscall.UTF16ToString(lpVolumeNameBuffer), nil
+}