imageI’ll admit this is an odd topic for me to write about since my job pretty far away from that part of the world, but our PM team at MS is building a set of demos for which we need some semi-random and fun input data that doesn’t change all that rapidly. So we thought that reading the temperature off hard drives would be a nice input. But how to get at it?

The solution is to use the WMI interface for ATAPI to get at the SMART data. Binging the subject you’ll find a ton of little snippets that have one thing in common: ‘magic’. Somehow, you get at the ‘VendorSpecific’ structure of the SMART data using WMI and then you believe that byte number 115 is the one that holds the temperature. Of course that’s not what someone who’s doing protocol in their day-job would ever settle for. So I’ve been digging around a little and found a description of the structure and grabbed the attribute value list from Wikipedia, shook it all up a little and out came the little program below.

The app grabs the vendor specific array from the ATAPI data, shreds it into a set of structures, and dumps it out. Code here, zip file at the bottom.

// (c) Microsoft Corporation
// Author: Clemens Vasters (clemensv@microsoft.com)
// Code subject to MS-PL: http://opensource.org/licenses/ms-pl.html 
// SMART Attributes and Background: http://en.wikipedia.org/wiki/S.M.A.R.T.
// SMART Attributes Overview: http://www.t13.org/Documents/UploadedDocuments/docs2005/e05171r0-ACS-SMARTAttributes_Overview.pdf
 
namespace SmartDataApp
{
    using System;
    using System.Collections.Generic;
    using System.Management;
    using System.Runtime.InteropServices;
 
    public enum SmartAttributeType : byte
    {
        ReadErrorRate = 0x01,
        ThroughputPerformance = 0x02,
        SpinUpTime = 0x03,
        StartStopCount = 0x04,
        ReallocatedSectorsCount = 0x05,
        ReadChannelMargin = 0x06,
        SeekErrorRate = 0x07,
        SeekTimePerformance = 0x08,
        PowerOnHoursPOH = 0x09,
        SpinRetryCount = 0x0A,
        CalibrationRetryCount = 0x0B,
        PowerCycleCount = 0x0C,
        SoftReadErrorRate = 0x0D,
        SATADownshiftErrorCount = 0xB7,
        EndtoEnderror = 0xB8,
        HeadStability = 0xB9,
        InducedOpVibrationDetection = 0xBA,
        ReportedUncorrectableErrors = 0xBB,
        CommandTimeout = 0xBC,
        HighFlyWrites = 0xBD,
        AirflowTemperatureWDC = 0xBE,
        TemperatureDifferencefrom100 = 0xBE,
        GSenseErrorRate = 0xBF,
        PoweroffRetractCount = 0xC0,
        LoadCycleCount = 0xC1,
        Temperature = 0xC2,
        HardwareECCRecovered = 0xC3,
        ReallocationEventCount = 0xC4,
        CurrentPendingSectorCount = 0xC5,
        UncorrectableSectorCount = 0xC6,
        UltraDMACRCErrorCount = 0xC7,
        MultiZoneErrorRate = 0xC8,
        WriteErrorRateFujitsu = 0xC8,
        OffTrackSoftReadErrorRate = 0xC9,
        DataAddressMarkerrors = 0xCA,
        RunOutCancel = 0xCB,
        SoftECCCorrection = 0xCC,
        ThermalAsperityRateTAR = 0xCD,
        FlyingHeight = 0xCE,
        SpinHighCurrent = 0xCF,
        SpinBuzz = 0xD0,
        OfflineSeekPerformance = 0xD1,
        VibrationDuringWrite = 0xD3,
        ShockDuringWrite = 0xD4,
        DiskShift = 0xDC,
        GSenseErrorRateAlt = 0xDD,
        LoadedHours = 0xDE,
        LoadUnloadRetryCount = 0xDF,
        LoadFriction = 0xE0,
        LoadUnloadCycleCount = 0xE1,
        LoadInTime = 0xE2,
        TorqueAmplificationCount = 0xE3,
        PowerOffRetractCycle = 0xE4,
        GMRHeadAmplitude = 0xE6,
        DriveTemperature = 0xE7,
        HeadFlyingHours = 0xF0,
        TransferErrorRateFujitsu = 0xF0,
        TotalLBAsWritten = 0xF1,
        TotalLBAsRead = 0xF2,
        ReadErrorRetryRate = 0xFA,
        FreeFallProtection = 0xFE,
    }
 
    public class SmartData
    {
        readonly Dictionary<SmartAttributeType, SmartAttribute> attributes;
        readonly ushort structureVersion;
 
        public SmartData(byte[] arrVendorSpecific)
        {
            attributes = new Dictionary<SmartAttributeType, SmartAttribute>();
            for (int offset = 2; offset < arrVendorSpecific.Length; )
            {
                var a = FromBytes<SmartAttribute>(arrVendorSpecific, ref offset, 12);
                // Attribute values 0x00, 0xfe, 0xff are invalid
                if (a.AttributeType != 0x00 && (byte)a.AttributeType != 0xfe && (byte)a.AttributeType != 0xff)
                {
                    attributes[a.AttributeType] = a;
                }
            }
            structureVersion = (ushort)(arrVendorSpecific[0] * 256 + arrVendorSpecific[1]);
        }
 
        public ushort StructureVersion
        {
            get
            {
                return this.structureVersion;
            }
        }
 
        public SmartAttribute this[SmartAttributeType v]
        {
            get
            {
                return this.attributes[v];
            }
        }
 
        public IEnumerable<SmartAttribute> Attributes
        {
            get
            {
                return this.attributes.Values;
            }
        }
 
        static T FromBytes<T>(byte[] bytearray, ref int offset, int count)
        {
            IntPtr ptr = IntPtr.Zero;
 
            try
            {
                ptr = Marshal.AllocHGlobal(count);
                Marshal.Copy(bytearray, offset, ptr, count);
                offset += count;
                return (T)Marshal.PtrToStructure(ptr, typeof(T));
            }
            finally
            {
                if (ptr != IntPtr.Zero)
                {
                    Marshal.FreeHGlobal(ptr);
                }
            }
        }
    }
 
    [StructLayout(LayoutKind.Sequential)]
    public struct SmartAttribute
    {
        public SmartAttributeType AttributeType;
        public ushort Flags;
        public byte Value;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
        public byte[] VendorData;
 
        public bool Advisory
        {
            get
            {
                return (Flags & 0x1) == 0x0; // Bit 0 unset?
            }
        }
        public bool FailureImminent
        {
            get
            {
                return (Flags & 0x1) == 0x1; // Bit 0 set?
            }
        }
        public bool OnlineDataCollection
        {
            get
            {
                return (Flags & 0x2) == 0x2; // Bit 0 set?
            }
        }
 
    }
 
    public class Program
    {
        public static void Main()
        {
            try
            {
                var searcher = new ManagementObjectSearcher("root\\WMI", "SELECT * FROM MSStorageDriver_ATAPISmartData");
 
                foreach (ManagementObject queryObj in searcher.Get())
                {
                    Console.WriteLine("-----------------------------------");
                    Console.WriteLine("MSStorageDriver_ATAPISmartData instance");
                    Console.WriteLine("-----------------------------------");
 
                    var arrVendorSpecific = (byte[])queryObj.GetPropertyValue("VendorSpecific");
 
                    // Create SMART data from 'vendor specific' array
                    var d = new SmartData(arrVendorSpecific);
                    foreach (var b in d.Attributes)
                    {
                        Console.Write("{0} :{1} : ", b.AttributeType, b.Value);
                        foreach (byte vendorByte in b.VendorData)
                        {
                            Console.Write("{0:x} ", vendorByte);
                        }
                        Console.WriteLine();
                    }
 
                }
            }
            catch (ManagementException e)
            {
                Console.WriteLine("An error occurred while querying for WMI data: " + e.Message);
            }
        }
    }
}

 

SmartDataProgram.zip (2.25 KB)