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I would like to change the performance and behaviour of my C++ application, according to whether the system drive is an SSD or not. Example:

  • With SSD, I want my gameserver application to load each map fully, with all objects in order to maximize performance.
  • With HDD, I want my gameserver application to load only the essential objects and entities in each map, with no external objects loaded.

I've seen http://msdn.microsoft.com/en-gb/library/windows/desktop/aa364939(v=vs.85).aspx, which is a way of determining if a certain drive is a HDD, CD ROM, DVD ROM, Removable Media, etc, but it STILL can't detect whether the main system drive is an SSD. I've also seen Is there any way of detecting if a drive is a SSD?, but the solution only applies to Linux.

I thought that I could somehow generate a large fine (500MB), and then time how long it takes to write the file, but however other system variables can easily influence the result.

In Windows, using C++, is there any way to get whether the main system drive is an SSD or not?

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    This sounds like a complicated issue that could be easier dealt with by a user-controllable switch. Commented Apr 29, 2014 at 11:18
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    I would go with measuring the time, as it's the speed that the important thing and not the fact that it's an SSD in itsself. Commented Apr 29, 2014 at 11:19
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    I may be daft as a doornail today, but why would you preload if you have a fast disk with less latency, and not on the slow disk? Anyhow, since this is a server: why don't you just make the behaviour manually configurable? That's more future-proof, less hassle, and you can develop, debug and test both implementations on one machine. Commented Apr 29, 2014 at 11:25
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    Why would you want to change how your application acts based on what the main system drive is? Your application and/or files may not be on that drive, or through use of junctions they could be spread across several drives. You also can't assume that the pagefile (if one exists) is located on the main system drive. Commented Apr 29, 2014 at 12:50
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    @cybermonkey Thank you for the bounty. I don't feel like I deserved that, so I will try to earn it. Commented Aug 26, 2015 at 11:57

6 Answers 6

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Having done some research and using the info from the answers on this page, here's my implementation using C WinAPIs for Windows 7 and later:

//Open drive as such: "\\?\PhysicalDriveX" where X is the drive number //INFO: To get drive number from a logical drive letter, check this method: // (But keep in mind that a single logical drive, or a volume, // can span across several physical drives, as a "spanned volume.") // http://stackoverflow.com/a/11683906/843732 #include <WinIoCtl.h> #include <Ntddscsi.h> DWORD bytesReturned; //As an example, let's test 1st physical drive HANDLE hDevice = ::CreateFile(L"\\\\?\\PhysicalDrive0", GENERIC_READ | GENERIC_WRITE, //We need write access to send ATA command to read RPMs FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL); if(hDevice != INVALID_HANDLE_VALUE) { //Check TRIM -- should be Y for SSD _tprintf(L"TRIM="); STORAGE_PROPERTY_QUERY spqTrim; spqTrim.PropertyId = (STORAGE_PROPERTY_ID)StorageDeviceTrimProperty; spqTrim.QueryType = PropertyStandardQuery; bytesReturned = 0; DEVICE_TRIM_DESCRIPTOR dtd = {0}; if(::DeviceIoControl(hDevice, IOCTL_STORAGE_QUERY_PROPERTY, &spqTrim, sizeof(spqTrim), &dtd, sizeof(dtd), &bytesReturned, NULL) && bytesReturned == sizeof(dtd)) { //Got it _tprintf(L"%s", dtd.TrimEnabled ? L"Y" : L"N"); } else { //Failed int err = ::GetLastError(); _tprintf(L"?"); } //Check the seek-penalty value -- should be N for SSD _tprintf(L", seekPenalty="); STORAGE_PROPERTY_QUERY spqSeekP; spqSeekP.PropertyId = (STORAGE_PROPERTY_ID)StorageDeviceSeekPenaltyProperty; spqSeekP.QueryType = PropertyStandardQuery; bytesReturned = 0; DEVICE_SEEK_PENALTY_DESCRIPTOR dspd = {0}; if(::DeviceIoControl(hDevice, IOCTL_STORAGE_QUERY_PROPERTY, &spqSeekP, sizeof(spqSeekP), &dspd, sizeof(dspd), &bytesReturned, NULL) && bytesReturned == sizeof(dspd)) { //Got it _tprintf(L"%s", dspd.IncursSeekPenalty ? L"Y" : L"N"); } else { //Failed int err = ::GetLastError(); _tprintf(L"?"); } //Get drive's RPMs reading -- should be 1 for SSD //CODE SOURCE: https://emoacht.wordpress.com/2012/11/06/csharp-ssd/ _tprintf(L", RPM="); ATAIdentifyDeviceQuery id_query; memset(&id_query, 0, sizeof(id_query)); id_query.header.Length = sizeof(id_query.header); id_query.header.AtaFlags = ATA_FLAGS_DATA_IN; id_query.header.DataTransferLength = sizeof(id_query.data); id_query.header.TimeOutValue = 5; //Timeout in seconds id_query.header.DataBufferOffset = offsetof(ATAIdentifyDeviceQuery, data[0]); id_query.header.CurrentTaskFile[6] = 0xec; // ATA IDENTIFY DEVICE bytesReturned = 0; if(::DeviceIoControl(hDevice, IOCTL_ATA_PASS_THROUGH, &id_query, sizeof(id_query), &id_query, sizeof(id_query), &bytesReturned, NULL) && bytesReturned == sizeof(id_query)) { //Got it //Index of nominal media rotation rate //SOURCE: http://www.t13.org/documents/UploadedDocuments/docs2009/d2015r1a-ATAATAPI_Command_Set_-_2_ACS-2.pdf // 7.18.7.81 Word 217 //QUOTE: Word 217 indicates the nominal media rotation rate of the device and is defined in table: // Value Description // -------------------------------- // 0000h Rate not reported // 0001h Non-rotating media (e.g., solid state device) // 0002h-0400h Reserved // 0401h-FFFEh Nominal media rotation rate in rotations per minute (rpm) // (e.g., 7 200 rpm = 1C20h) // FFFFh Reserved #define kNominalMediaRotRateWordIndex 217 _tprintf(L"%d", (UINT)id_query.data[kNominalMediaRotRateWordIndex]); } else { //Failed int err = ::GetLastError(); _tprintf(L"?"); } _tprintf(L"\n"); ::CloseHandle(hDevice); }

In case you don't have driver DDK includes, here're some definitions:

#ifndef StorageDeviceTrimProperty #define StorageDeviceTrimProperty 8 #endif #ifndef DEVICE_TRIM_DESCRIPTOR typedef struct _DEVICE_TRIM_DESCRIPTOR { DWORD Version; DWORD Size; BOOLEAN TrimEnabled; } DEVICE_TRIM_DESCRIPTOR, *PDEVICE_TRIM_DESCRIPTOR; #endif #ifndef StorageDeviceSeekPenaltyProperty #define StorageDeviceSeekPenaltyProperty 7 #endif #ifndef DEVICE_SEEK_PENALTY_DESCRIPTOR typedef struct _DEVICE_SEEK_PENALTY_DESCRIPTOR { DWORD Version; DWORD Size; BOOLEAN IncursSeekPenalty; } DEVICE_SEEK_PENALTY_DESCRIPTOR, *PDEVICE_SEEK_PENALTY_DESCRIPTOR; #endif struct ATAIdentifyDeviceQuery { ATA_PASS_THROUGH_EX header; WORD data[256]; };

Lastly, conclusion of my tests.

I have several Samsung SSDs connected via a SATA cable, and one PCIe SSD drive that is connected directly to the logic board using PCIe slot. I also have one large internal Western Digital HDD (spinning drive) that is also connected via a SATA cable, and a couple of external spinning HDDs.

Here's what I get for them:

Samsung SSD 256GB: TRIM=Y, seekPenalty=N, RPM=1 Samsung SSD 500GB: TRIM=Y, seekPenalty=N, RPM=1 PCIs SSD: TRIM=Y, seekPenalty=?, RPM=0 Internal WD HDD: TRIM=N, seekPenalty=?, RPM=0 External WD HDD: TRIM=?, seekPenalty=?, RPM=? External Cavalry HDD: TRIM=?, seekPenalty=Y, RPM=?

So as you see, in my case, the only parameter that is correct for all 6 drives is TRIM. I'm not saying that it will be in your case as well. It's just my finding with the drives that I own.

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2 Comments

Presumably you have to be running elevated for this to work.
@PaulSanders: Yes, if you need to get the disk rotation speed. (See comments in the code.) Otherwise w/o it, you don't need an admin to get the TRIM and seek penalty. In that case when calling CreateFile, specify dwDesiredAccess parameter as 0.
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I believe you are using the wrong tool. Instead of making assumptions based on a drive being an SSD you should make your code work well with slow and fast drives, for example by loading the essential objects first and the rest later. In three years the invention of [...] may make regular hard drives faster than SSDs which would break your code. Going purely based on speed will also work for RAM discs, NFS, USB3.0-sticks and other stuff you didn't or cannot thing about.

EDIT: A HDD is not actually the same as a slow SSD. While they are both fast at reading and writing a HDD needs significant time for seeking. It thus makes sense to use two different access strategies: picking the important data via random access for the SSD and sequentially reading for the HDD. You will probably get away with only implementing the sequential strategy as that should still work ok with SSDs. It makes more sense to check for a HDD instead of a SSD though, because you need to treat the HDD special while SSD, RAMdisc, NFS and so on should not suffer from seek times and can thus be treated the same.

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You can use the Microsoft WMI Class MSFT_PhysicalDisk. The mediatype of 4 is SSD and SpindleSpeed will be 0.

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2 Comments

Both this answer and MSDN conveniently omit any info on how to get this MSFT_PhysicalDisk class for a specified drive.
I tried querying MSFT_PhysicalDisk but almost all Property values return null.
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Yes, there is a high chance of determining whether a drive is an SSD. SSD typically support the TRIM command, so I would check to see if the drive supports the TRIM command.

In Windows, you can use IOCTL_STORAGE_QUERY_PROPERTY to get the DEVICE_TRIM_DESCRIPTOR structure which will tell you if TRIM is enabled.

If you really know what you're doing, you can get the raw IDENTIFY DEVICE package, and interpret the data yourself. For SATA drives it would be word 169 bit 0.

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7 Comments

Very nice. It actually works for all my SSDs. Now how about detecting the drive's RPMs, which SSD should report as 0 or none. Does anyone have a working code for that? Evidently IOCTL_SCSI_MINIPORT could be used for that. The best I could find so far is this half-answered question: social.msdn.microsoft.com/Forums/en-US/…
The RPM is reported in the NOMINAL MEDIA ROTATION RATE field (word 217) of the IDENTIFY DEVICE package.
@tchau.dev do you mean DEVICE_TRIM_DESCRIPTOR->TrimEnabled is simply always equal to word169->bit0? (And, thus, if device reports "1" it only means that it supports TRIM, and doesn't mean that it is not actually functioning, e.g. like described here.)
I've seen an opposite statement - that DEVICE_TRIM_DESCRIPTOR indicates TRIM_is_actually_functioning, not the device_supports_TRIM.
@Igor there are two things in play here. (1) Windows API with DEVICE_TRIM_DESCRIPTOR, and (2) ATA specification regarding TRIM. (1) The TrimEnabled flag in DEVICE_TRIM_DESCRIPTOR state that TRIM is enabled or not. How Windows determine this is up to them, but they probably referred to the ATA spec. (2) Page 146 of the ATA spec will tell you that word 169, bit 0 indicate that TRIM is supported. Page 153, section 7.18.7.30 Word 69, tells you that these features sets are enabled.
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The best way I found was using the MSFT_PhysicalDisk in the ROOT\microsoft\windows\storage namespace with WMI

This gives you two properties

  • SpindleSpeed
  • MediaType

The Media Type gives you values

  • 0 Unspecified
  • 3 HDD
  • 4 SSD
  • 5 SCM

And a spindle speed of 0 is pretty self-explanatory

Main.cpp

#include <iostream> #include <windows.h>; #include <Wbemidl.h> #include <comdef.h> #include "StorageDevice.h" #include <vector> #pragma comment(lib, "wbemuuid.lib") using namespace::std; void IntializeCOM() { HRESULT hres; hres = CoInitializeEx(0, COINIT_MULTITHREADED); if (FAILED(hres)) { cout << "Failed to initialize COM library. Error code = 0x" << hex << hres << endl; // Program has failed. } // Step 2: -------------------------------------------------- // Set general COM security levels -------------------------- hres = CoInitializeSecurity( NULL, -1, // COM authentication NULL, // Authentication services NULL, // Reserved RPC_C_AUTHN_LEVEL_DEFAULT, // Default authentication RPC_C_IMP_LEVEL_IMPERSONATE, // Default Impersonation NULL, // Authentication info EOAC_NONE, // Additional capabilities NULL // Reserved ); if (FAILED(hres)) { cout << "Failed to initialize security. Error code = 0x" << hex << hres << endl; CoUninitialize(); // Program has failed. } } void SetupWBEM(IWbemLocator*& pLoc, IWbemServices*& pSvc) { // Step 3: --------------------------------------------------- // Obtain the initial locator to WMI ------------------------- HRESULT hres; //IWbemLocator *pLoc = NULL; hres = CoCreateInstance(CLSID_WbemLocator, 0, CLSCTX_INPROC_SERVER, IID_IWbemLocator, (LPVOID *)&pLoc); if (FAILED(hres)) { cout << "Failed to create IWbemLocator object." << " Err code = 0x" << hex << hres << endl; CoUninitialize(); } // Step 4: ----------------------------------------------------- // Connect to WMI through the IWbemLocator::ConnectServer method //IWbemServices *pSvc = NULL; // Connect to the ROOT\\\microsoft\\windows\\storage namespace with // the current user and obtain pointer pSvc // to make IWbemServices calls. hres = pLoc->ConnectServer( _bstr_t(L"ROOT\\microsoft\\windows\\storage"), // Object path of WMI namespace NULL, // User name. NULL = current user NULL, // User password. NULL = current 0, // Locale. NULL indicates current NULL, // Security flags. 0, // Authority (for example, Kerberos) 0, // Context object &pSvc // pointer to IWbemServices proxy ); if (FAILED(hres)) { cout << "Could not connect. Error code = 0x" << hex << hres << endl; pLoc->Release(); CoUninitialize(); } // Step 5: -------------------------------------------------- // Set security levels on the proxy ------------------------- hres = CoSetProxyBlanket( pSvc, // Indicates the proxy to set RPC_C_AUTHN_WINNT, // RPC_C_AUTHN_xxx RPC_C_AUTHZ_NONE, // RPC_C_AUTHZ_xxx NULL, // Server principal name RPC_C_AUTHN_LEVEL_CALL, // RPC_C_AUTHN_LEVEL_xxx RPC_C_IMP_LEVEL_IMPERSONATE, // RPC_C_IMP_LEVEL_xxx NULL, // client identity EOAC_NONE // proxy capabilities ); if (FAILED(hres)) { cout << "Could not set proxy blanket. Error code = 0x" << hex << hres << endl; pSvc->Release(); pLoc->Release(); CoUninitialize(); } } int main() { IWbemLocator *wbemLocator = NULL; IWbemServices *wbemServices = NULL; IntializeCOM(); SetupWBEM(wbemLocator, wbemServices); IEnumWbemClassObject* storageEnumerator = NULL; HRESULT hres = wbemServices->ExecQuery( bstr_t("WQL"), bstr_t("SELECT * FROM MSFT_PhysicalDisk"), WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, NULL, &storageEnumerator); if (FAILED(hres)) { cout << "Query for MSFT_PhysicalDisk. Error code = 0x" << hex << hres << endl; wbemServices->Release(); wbemLocator->Release(); CoUninitialize(); } IWbemClassObject *storageWbemObject = NULL; ULONG uReturn = 0; vector<StorageDevice> storageDevices; while (storageEnumerator) { HRESULT hr = storageEnumerator->Next(WBEM_INFINITE, 1, &storageWbemObject, &uReturn); if (0 == uReturn || hr != S_OK) { break; } StorageDevice storageDevice; VARIANT deviceId; VARIANT busType; VARIANT healthStatus; VARIANT spindleSpeed; VARIANT mediaType; storageWbemObject->Get(L"DeviceId", 0, &deviceId, 0, 0); storageWbemObject->Get(L"BusType", 0, &busType, 0, 0); storageWbemObject->Get(L"HealthStatus", 0, &healthStatus, 0, 0); storageWbemObject->Get(L"SpindleSpeed", 0, &spindleSpeed, 0, 0); storageWbemObject->Get(L"MediaType", 0, &mediaType, 0, 0); storageDevice.DeviceId = deviceId.bstrVal == NULL ? "" : _bstr_t(deviceId.bstrVal); storageDevice.BusType = busType.uintVal; storageDevice.HealthStatus = healthStatus.uintVal; storageDevice.SpindleSpeed = spindleSpeed.uintVal; storageDevice.MediaType = mediaType.uintVal; storageDevices.push_back(storageDevice); storageWbemObject->Release(); } }

The programs stores the disk properties in a strongly typed object "storageDevice" here, and pushed it onto a vector so we can use it later

StorageDevice.h

#pragma once #include <iostream> using namespace::std; class StorageDevice { public: StorageDevice(); ~StorageDevice(); string DeviceId; int BusType; int HealthStatus; int SpindleSpeed; int MediaType; };

StorageDevice.cpp

#include "StorageDevice.h" StorageDevice::StorageDevice() { } StorageDevice::~StorageDevice() { }

Video tutorial and source code c++ download here

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1 Comment

An exceptional answer, thank you. I've been having trouble getting the data for MSFT_PhysicalDisk, turns out the correct root is key. One question: do you have any idea how to find which of these WMI storage devices a folder is located on?
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do not bother of drive type. make a measurement by reading some of your game data that is loaded anyways and decide which strategy to use. (do not forget to make an configuration option :)

nether the less my gut instinct tells me that the approach is wrong. if someone has a slow disk then preloading should be more important since on the fly loading will cause stuttering. On the other side if the drive is fast enough i do not need to waste memory because i can load data on the fly fast enough.

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There are cases where you need to know the type, not only performance: e.g. implementing disk utilities, including but not limited to defragmentation, etc.
@AdrianMaire sure but the current use case in question is a game server also for most diskutils preloading data is not a thing.

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