Debunking the Vista Remote Differential Compression Myth

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Ned here again. Have you ever visited Snopes.com? It’s a terrific urban legend reference where they research folklore. Snopes is the place you go to find out if eating Thanksgiving turkey makes you sleepy (it doesn’t), if Coca Cola can dissolve a tooth overnight (it can’t), or if a man really did live in a Paris airport for 8 years (he did!).

Today I’m going to talk about another urban legend – that removing the Remote Differential Compression feature from Windows Vista will make your file copying faster over the network.

Background on RDC

Remote Differential Compression (RDC) is a Microsoft algorithm that was originally created for DFSR five years ago. RDC divides a file’s data into chunks by using signatures. When a file exists on two computers and the file is modified, only the differing chunks need to be sent to the other computer.

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An application needs to be specifically written to support RDC. Windows Vista and Windows 7 include MSRDC.DLL to allow apps like Windows Live Messenger to use that functionality.

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The feature can be turned on and off within the Control Panel “Program and Features” applet.

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When turned on, the MSRDC.DLL will exist in the %SYSTEMROOT%\System32 directory. When it’s turned off, this DLL is removed.

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The Myth

Unfortunately, the Internet is full of people telling you that RDC will somehow make your network communication slower. I have no idea how this got started, but this nonsense has been reprinted on thousands of websites by people unfamiliar with the Scientific Method. Folks have actually convinced themselves that turning this feature on or off has some affect on file transfer speeds. While there are a variety of things you can do to speed up Vista file copy performance, this isn’t one of them.

The Method

So after hearing this baloney for the umpteenth time, I set out to debunk it once and for all:

  • I setup a Windows Server 2008 SP2 file server and a Windows Vista SP2 client as virtual guests inside a Hyper-V host.
  • Each guest got 1GB of RAM and a virtual gigabit NIC.
  • I dropped a 3GB ISO file onto a share on the file server.
  • I used robocopy.exe (which automatically reports bytes per second and megabytes per minute) to copy that ISO file five times with MSRDC.DLL installed, then five more times with MSRDC.DLL removed.
  • In between every copy, I rebooted both the client and server to ensure that there was no caching of the file that might artificially improve my results.

The Results

Here is what I found after the ten total passes, with and without RDC installed:

Pass

With MSRDC.DLL

Without MSRDC.DLL

1st pass

 

1237.939

 

1210.479

 

2nd pass

 

1186.415

 

1330.882

 

3rd pass

 

1192.068

 

1175.328

 

4th pass

 

1111.13

 

1170.281

 

5th pass

 

1320.867

 

1153.863

 

 

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Hmmm… What if I sort my data points highest to lowest?

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Interesting. Let’s look at the actual averages:

With MSRDC.DLL installed: 1209.6838 MB/min

With MSRDC.DLL removed: 1208.1666 MB/min

Wait – so removing RDC actually made it slower? Not really – the variance there is well within any respectable margin of error. These results mean that the two sets of copies were 99.87% identical. Removing RDC did nothing at all. There are going to be various performance differences when copying a file, depending on what else happens on the network, what the computers are doing, and I think when people claim RDC removal made things ‘faster’, it’s because they are not testing repeatedly over time to see variance.

Maybe you want more proof? Alright, let’s go to the debugger.

  • I installed Notmyfault on my Vista client and configured the computer for a complete memory dump
  • I started yet another file copy, then I listed out the process and service information with TASKLIST.EXE and TASKLIST.EXE /SVC
  • After a few seconds, I intentionally crash dumped (the so-called “Blue Screen of Death”) the Vista computer. I then cracked open the MEMORY.DMP file in the Windows debugger

First, I listed loaded modules - all libraries and drivers loaded in the kernel memory space:

kd> lm start end module name 00000000`75f50000 00000000`75f88000 odbcint (deferred) 00000000`77aa0000 00000000`77b6d000 USER32 (deferred) 00000000`77b70000 00000000`77c9d000 kernel32 (deferred) 00000000`77ca0000 00000000`77e26000 ntdll (export symbols) ntdll.dll 00000000`77e50000 00000000`77e54000 Normaliz (deferred) 00000000`ffec0000 00000000`fff41000 Robocopy (deferred) 000007fe`f4be0000 000007fe`f4d30000 MFC42u (deferred) 000007fe`f9200000 000007fe`f9271000 ODBC32 (deferred) 000007fe`fbd90000 000007fe`fbe30000 COMCTL32 (deferred) 000007fe`fcc80000 000007fe`fce79000 comctl32_7fefcc80000 (deferred) 000007fe`fe420000 000007fe`fe4ac000 COMDLG32 (deferred) 000007fe`fe620000 000007fe`fe64d000 IMM32 (deferred) 000007fe`fe6f0000 000007fe`fe8c8000 ole32 (deferred) 000007fe`fe8d0000 000007fe`fe92f000 iertutil (deferred) 000007fe`fe930000 000007fe`fe937000 NSI (deferred) 000007fe`feb80000 000007fe`fecc3000 RPCRT4 (deferred) 000007fe`fecd0000 000007fe`fed6a000 USP10 (deferred) 000007fe`fed70000 000007fe`fedb4000 WS2_32 (deferred) 000007fe`fedc0000 000007fe`fee33000 SHLWAPI (deferred) 000007fe`fee40000 000007fe`feedc000 msvcrt (deferred) 000007fe`feee0000 000007fe`fefe2000 MSCTF (deferred) 000007fe`feff0000 000007fe`feffd000 LPK (deferred) 000007fe`ff000000 000007fe`ffc53000 SHELL32 (deferred) 000007fe`ffc60000 000007fe`ffd5e000 WININET (deferred) 000007fe`ffd60000 000007fe`ffdc4000 GDI32 (deferred) 000007fe`ffdd0000 000007fe`ffea3000 OLEAUT32 (deferred) 000007fe`ffeb0000 000007fe`fffb8000 ADVAPI32 (deferred) fffff800`01804000 fffff800`01d1c000 nt (private) fffff800`01d1c000 fffff800`01d62000 hal (deferred) fffff960`000c0000 fffff960`00371000 win32k (deferred) fffff960`00480000 fffff960`0049e000 dxg (deferred) fffff960`00600000 fffff960`0060a000 TSDDD (deferred) fffff960`00820000 fffff960`0082b000 VMBusVideoD (deferred) fffffa60`00602000 fffffa60`0060c000 kdcom (deferred) fffffa60`0060c000 fffffa60`00647000 mcupdate_GenuineIntel (deferred) fffffa60`00647000 fffffa60`0065b000 PSHED (deferred) fffffa60`0065b000 fffffa60`006b8000 CLFS (deferred) fffffa60`006b8000 fffffa60`0076a000 CI (deferred) fffffa60`0076a000 fffffa60`007d0000 volmgrx (deferred) fffffa60`007d0000 fffffa60`007e4000 NDProxy (deferred) fffffa60`007e4000 fffffa60`007ef000 Msfs (deferred) fffffa60`007ef000 fffffa60`00800000 Npfs (deferred) fffffa60`00808000 fffffa60`008e2000 Wdf01000 (deferred) fffffa60`008e2000 fffffa60`008f0000 WDFLDR (deferred) fffffa60`008f0000 fffffa60`00946000 acpi (deferred) fffffa60`00946000 fffffa60`0094f000 WMILIB (deferred) fffffa60`0094f000 fffffa60`00959000 msisadrv (deferred) fffffa60`00959000 fffffa60`00989000 pci (deferred) fffffa60`00989000 fffffa60`0099e000 partmgr (deferred) fffffa60`0099e000 fffffa60`009b2000 volmgr (deferred) fffffa60`009b2000 fffffa60`009ba000 intelide (deferred) fffffa60`009ba000 fffffa60`009ca000 PCIIDEX (deferred) fffffa60`009ca000 fffffa60`009fd000 netvsc60 (deferred) fffffa60`00a00000 fffffa60`00a3d000 vmbus (deferred) fffffa60`00a3d000 fffffa60`00a51000 winhv (deferred) fffffa60`00a51000 fffffa60`00a64000 mountmgr (deferred) fffffa60`00a64000 fffffa60`00a6c000 atapi (deferred) fffffa60`00a6c000 fffffa60`00a90000 ataport (deferred) fffffa60`00a90000 fffffa60`00ad7000 fltmgr (deferred) fffffa60`00ad7000 fffffa60`00aeb000 fileinfo (deferred) fffffa60`00aeb000 fffffa60`00af8000 storvsc (deferred) fffffa60`00af8000 fffffa60`00b55000 storport (deferred) fffffa60`00b55000 fffffa60`00bdb000 ksecdd (deferred) fffffa60`00bdb000 fffffa60`00bee000 intelppm (deferred) fffffa60`00bee000 fffffa60`00bf7000 rdpencdd (deferred) fffffa60`00bf7000 fffffa60`00c00000 rasacd (deferred) fffffa60`00c00000 fffffa60`00c0e000 vga (deferred) fffffa60`00c0f000 fffffa60`00dd2000 ndis (deferred) fffffa60`00dd2000 fffffa60`00dee000 cdrom (deferred) fffffa60`00dee000 fffffa60`00df7000 Null (deferred) fffffa60`00df7000 fffffa60`00e00000 RDPCDD (deferred) fffffa60`00e00000 fffffa60`00e0a000 Fs_Rec (deferred) fffffa60`00e0c000 fffffa60`00e5c000 msrpc (deferred) fffffa60`00e5c000 fffffa60`00eb5000 NETIO (deferred) fffffa60`00eb5000 fffffa60`00ede000 fvevol (deferred) fffffa60`00ede000 fffffa60`00f0a000 CLASSPNP (deferred) fffffa60`00f29000 fffffa60`00f35000 tunnel (deferred) fffffa60`00f35000 fffffa60`00f4b000 i8042prt (deferred) fffffa60`00f4b000 fffffa60`00f59000 kbdclass (deferred) fffffa60`00f59000 fffffa60`00f65000 mouclass (deferred) fffffa60`00f65000 fffffa60`00f82000 serial (deferred) fffffa60`00f82000 fffffa60`00f8e000 serenum (deferred) fffffa60`00f8e000 fffffa60`00f9b000 fdc (deferred) fffffa60`00f9b000 fffffa60`00fad000 HIDCLASS (deferred) fffffa60`00fad000 fffffa60`00fb7000 VMBusVideoM (deferred) fffffa60`00fb7000 fffffa60`00fdc000 VIDEOPRT (deferred) fffffa60`00fdc000 fffffa60`00fec000 watchdog (deferred) fffffa60`00fec000 fffffa60`00ff5000 vms3cap (deferred) fffffa60`00ff5000 fffffa60`01000000 mouhid (deferred) fffffa60`01000000 fffffa60`01007b80 HIDPARSE (deferred) fffffa60`01008000 fffffa60`0117d000 tcpip (deferred) fffffa60`0117d000 fffffa60`011a9000 fwpkclnt (deferred) fffffa60`011a9000 fffffa60`011b9000 vmstorfl (deferred) fffffa60`011b9000 fffffa60`011e5000 ecache (deferred) fffffa60`011e5000 fffffa60`011ef000 crcdisk (deferred) fffffa60`01208000 fffffa60`01388000 Ntfs (deferred) fffffa60`01388000 fffffa60`013cc000 volsnap (deferred) fffffa60`013cc000 fffffa60`013d4000 spldr (deferred) fffffa60`013d4000 fffffa60`013e6000 mup (deferred) fffffa60`013e6000 fffffa60`013fa000 disk (deferred) fffffa60`013fa000 fffffa60`013ff500 VMBusHID (deferred) fffffa60`02200000 fffffa60`0220b000 flpydisk (deferred) fffffa60`0220f000 fffffa60`02248000 msiscsi (deferred) fffffa60`02248000 fffffa60`02255000 TDI (deferred) fffffa60`02255000 fffffa60`02278000 rasl2tp (deferred) fffffa60`02278000 fffffa60`02284000 ndistapi (deferred) fffffa60`02284000 fffffa60`022b5000 ndiswan (deferred) fffffa60`022b5000 fffffa60`022c5000 raspppoe (deferred) fffffa60`022c5000 fffffa60`022e3000 raspptp (deferred) fffffa60`022e3000 fffffa60`022fb000 rassstp (deferred) fffffa60`022fb000 fffffa60`02395000 rdpdr (deferred) fffffa60`02395000 fffffa60`023a8000 termdd (deferred) fffffa60`023a8000 fffffa60`023a9480 swenum (deferred) fffffa60`023aa000 fffffa60`023de000 ks (deferred) fffffa60`023de000 fffffa60`023e9000 mssmbios (deferred) fffffa60`023e9000 fffffa60`023f9000 umbus (deferred) fffffa60`02401000 fffffa60`0241e000 tdx (deferred) fffffa60`0241e000 fffffa60`02439000 smb (deferred) fffffa60`02439000 fffffa60`024a4000 afd (deferred) fffffa60`024a4000 fffffa60`024e8000 netbt (deferred) fffffa60`024e8000 fffffa60`02506000 pacer (deferred) fffffa60`02506000 fffffa60`02514000 nm3 (deferred) fffffa60`02514000 fffffa60`02523000 netbios (deferred) fffffa60`02523000 fffffa60`0253e000 wanarp (deferred) fffffa60`0253e000 fffffa60`0258b000 rdbss (deferred) fffffa60`0258b000 fffffa60`02597000 nsiproxy (deferred) fffffa60`02597000 fffffa60`025c0000 srvnet (deferred) fffffa60`025c0000 fffffa60`025de000 bowser (deferred) fffffa60`02c08000 fffffa60`02c7e000 csc (deferred) fffffa60`02c7e000 fffffa60`02c9b000 dfsc (deferred) fffffa60`02c9b000 fffffa60`02cb7000 cdfs (deferred) fffffa60`02cb7000 fffffa60`02cc5000 crashdmp (deferred) fffffa60`02cc5000 fffffa60`02cd1000 dump_dumpata (deferred) fffffa60`02cd1000 fffffa60`02cd9000 dump_atapi (deferred) fffffa60`02cd9000 fffffa60`02cec000 dump_dumpfve (deferred) fffffa60`02cec000 fffffa60`02cf8000 Dxapi (deferred) fffffa60`02cf8000 fffffa60`02d1a000 luafv (deferred) fffffa60`02d1a000 fffffa60`02d2e000 lltdio (deferred) fffffa60`02d2e000 fffffa60`02d46000 rspndr (deferred) fffffa60`02d46000 fffffa60`02de5000 HTTP (deferred) fffffa60`02de5000 fffffa60`02dff000 mpsdrv (deferred) fffffa60`03805000 fffffa60`0382c000 mrxdav (deferred) fffffa60`0382c000 fffffa60`03855000 mrxsmb (deferred) fffffa60`03855000 fffffa60`0389e000 mrxsmb10 (deferred) fffffa60`0389e000 fffffa60`038bd000 mrxsmb20 (deferred) fffffa60`038bd000 fffffa60`038ef000 srv2 (deferred) fffffa60`038ef000 fffffa60`03980000 srv (deferred) fffffa60`03c03000 fffffa60`03c9d000 spsys (deferred) fffffa60`03c9d000 fffffa60`03d53000 peauth (deferred) fffffa60`03d53000 fffffa60`03d5e000 secdrv (deferred) fffffa60`03d5e000 fffffa60`03d6e000 tcpipreg (deferred) fffffa60`03d6e000 fffffa60`03d75000 myfault (deferred)            

Note how MSRDC.DLL is not loaded in memory in the Kernel space. It’s still possible that a given process or service might have it loaded though, so then I listed all processes to see which ones would be interesting and likely to be involved in file copies. The TASKLIST output comes in handy here to see which PID is which hexadecimal CID value. In my case though I dumped them all just for exploratory purposes.

kd> !process 0 0

<snipped out some>

PROCESS fffffa8009af9040 SessionId: 1 Cid: 0790 Peb: 7fffffdf000 ParentCid: 0a08 DirBase: 34e57000 ObjectTable: fffff880066f60d0 HandleCount: 65. Image: Robocopy.exe

PROCESS fffffa800b9adc10 SessionId: 0 Cid: 0340 Peb: 7fffffd5000 ParentCid: 0280 DirBase: 1efc3000 ObjectTable: fffff8800634fb60 HandleCount: 522. Image: svchost.exe

 

 

 

 

I know that the Workstation Service is responsible for SMB file copying, and the robocopy process is definitely doing work, so I examined those.

kd> .process fffffa8009af9040 Implicit process is now fffffa80`09af9040 kd> !peb PEB at 000007fffffdf000 InheritedAddressSpace: No ReadImageFileExecOptions: No BeingDebugged: No ImageBaseAddress: 00000000ffec0000 Ldr 0000000077db2960 Ldr.Initialized: Yes Ldr.InInitializationOrderModuleList: 00000000001226c0 . 00000000001373c0 Ldr.InLoadOrderModuleList: 00000000001225d0 . 00000000001373a0 Ldr.InMemoryOrderModuleList: 00000000001225e0 . 00000000001373b0 Base TimeStamp Module ffec0000 479191ad Jan 19 00:59:09 2008 C:\Windows\system32\Robocopy.exe 77ca0000 49e0421d Apr 11 03:09:17 2009 C:\Windows\system32\ntdll.dll 77b70000 49e041d1 Apr 11 03:08:01 2009 C:\Windows\system32\kernel32.dll 7feffeb0000 49e040cb Apr 11 03:03:39 2009 C:\Windows\system32\ADVAPI32.dll 7fefeb80000 49e041ea Apr 11 03:08:26 2009 C:\Windows\system32\RPCRT4.dll 7fef4be0000 49e04151 Apr 11 03:05:53 2009 C:\Windows\system32\MFC42u.dll 7fefee40000 49e04189 Apr 11 03:06:49 2009 C:\Windows\system32\msvcrt.dll 77aa0000 49e0420e Apr 11 03:09:02 2009 C:\Windows\system32\USER32.dll 7feffd60000 49e04114 Apr 11 03:04:52 2009 C:\Windows\system32\GDI32.dll 7fefe6f0000 49e041cf Apr 11 03:07:59 2009 C:\Windows\system32\ole32.dll 7feffdd0000 49e041d2 Apr 11 03:08:02 2009 C:\Windows\system32\OLEAUT32.dll 7feffc60000 49e04252 Apr 11 03:10:10 2009 C:\Windows\system32\WININET.dll 7fefedc0000 49e041f4 Apr 11 03:08:36 2009 C:\Windows\system32\SHLWAPI.dll 77e50000 4549b4d2 Nov 02 05:05:22 2006 C:\Windows\system32\Normaliz.dll 7fefe8d0000 49e04146 Apr 11 03:05:42 2009 C:\Windows\system32\iertutil.dll 7fefed70000 49e0422d Apr 11 03:09:33 2009 C:\Windows\system32\WS2_32.dll 7fefe930000 4791adea Jan 19 02:59:38 2008 C:\Windows\system32\NSI.dll 7fef9200000 49e041c1 Apr 11 03:07:45 2009 C:\Windows\system32\ODBC32.dll 7fefbd90000 4791ac7c Jan 19 02:53:32 2008 C:\Windows\WinSxS\amd64_microsoft.windows.common-controls_6595b64144ccf1df_5.82.6001.18000_none_40ba501d3c2b20ff\COMCTL32.dll 7feff000000 49e041ef Apr 11 03:08:31 2009 C:\Windows\system32\SHELL32.dll 7fefe420000 49e041e9 Apr 11 03:08:25 2009 C:\Windows\system32\COMDLG32.dll 7fefe620000 49e0417d Apr 11 03:06:37 2009 C:\Windows\system32\IMM32.DLL 7fefeee0000 49e04184 Apr 11 03:06:44 2009 C:\Windows\system32\MSCTF.dll 7fefeff0000 4791ad25 Jan 19 02:56:21 2008 C:\Windows\system32\LPK.DLL 7fefecd0000 49e04211 Apr 11 03:09:05 2009 C:\Windows\system32\USP10.dll 7fefcc80000 49e041e9 Apr 11 03:08:25 2009 C:\Windows\WinSxS\amd64_microsoft.windows.common-controls_6595b64144ccf1df_6.0.6002.18005_none_1509f8bef40ee4da\comctl32.dll 75f50000 4549d310 Nov 02 07:14:24 2006 C:\Windows\system32\odbcint.dll

kd> .PROCESS fffffa800b9adc10 Implicit process is now fffffa80`0b9adc10 kd> !peb PEB at 000007fffffd5000 InheritedAddressSpace: No ReadImageFileExecOptions: No BeingDebugged: No ImageBaseAddress: 00000000ff820000 Ldr 0000000077db2960 Ldr.Initialized: Yes Ldr.InInitializationOrderModuleList: 00000000002125f0 . 0000000003a08ac0 Ldr.InLoadOrderModuleList: 0000000000212500 . 0000000003a08aa0 Ldr.InMemoryOrderModuleList: 0000000000212510 . 0000000003a08ab0 Base TimeStamp Module ff820000 47919291 Jan 19 01:02:57 2008 C:\Windows\system32\svchost.exe 77ca0000 49e0421d Apr 11 03:09:17 2009 C:\Windows\system32\ntdll.dll 77b70000 49e041d1 Apr 11 03:08:01 2009 C:\Windows\system32\kernel32.dll 7fefee40000 49e04189 Apr 11 03:06:49 2009 C:\Windows\system32\msvcrt.dll 7feffeb0000 49e040cb Apr 11 03:03:39 2009 C:\Windows\system32\ADVAPI32.dll 7fefeb80000 49e041ea Apr 11 03:08:26 2009 C:\Windows\system32\RPCRT4.dll 7fefd440000 49e0422f Apr 11 03:09:35 2009 C:\Windows\system32\NTMARTA.DLL 77aa0000 49e0420e Apr 11 03:09:02 2009 C:\Windows\system32\USER32.dll 7feffd60000 49e04114 Apr 11 03:04:52 2009 C:\Windows\system32\GDI32.dll 7fefe940000 49e0427e Apr 11 03:10:54 2009 C:\Windows\system32\WLDAP32.dll 7fefed70000 49e0422d Apr 11 03:09:33 2009 C:\Windows\system32\WS2_32.dll 7fefe930000 4791adea Jan 19 02:59:38 2008 C:\Windows\system32\NSI.dll 77e40000 47919b74 Jan 19 01:40:52 2008 C:\Windows\system32\PSAPI.DLL 7fefdce0000 49e041e3 Apr 11 03:08:19 2009 C:\Windows\system32\SAMLIB.dll 7fefe6f0000 49e041cf Apr 11 03:07:59 2009 C:\Windows\system32\ole32.dll 7fefe620000 49e0417d Apr 11 03:06:37 2009 C:\Windows\system32\IMM32.DLL 7fefeee0000 49e04184 Apr 11 03:06:44 2009 C:\Windows\system32\MSCTF.dll 7fefeff0000 4791ad25 Jan 19 02:56:21 2008 C:\Windows\system32\LPK.DLL 7fefecd0000 49e04211 Apr 11 03:09:05 2009 C:\Windows\system32\USP10.dll 7fefc1c0000 49e0419d Apr 11 03:07:09 2009 c:\windows\system32\es.dll 7feffdd0000 49e041d2 Apr 11 03:08:02 2009 C:\Windows\system32\OLEAUT32.dll 7fefc000000 49e041dd Apr 11 03:08:13 2009 c:\windows\system32\PROPSYS.dll 7fefd510000 49e041ed Apr 11 03:08:29 2009 C:\Windows\system32\rsaenh.dll 7fefe650000 4791acc9 Jan 19 02:54:49 2008 C:\Windows\system32\CLBCatQ.DLL 7fefc4b0000 4791adeb Jan 19 02:59:39 2008 c:\windows\system32\nsisvc.dll 7fefe250000 49e04210 Apr 11 03:09:04 2009 C:\Windows\system32\secur32.dll 7fefdb10000 49e04202 Apr 11 03:08:50 2009 C:\Windows\system32\CRYPT32.dll 7fefdcc0000 4791ad5c Jan 19 02:57:16 2008 C:\Windows\system32\MSASN1.dll 7fefe270000 49e04210 Apr 11 03:09:04 2009 C:\Windows\system32\USERENV.dll 7fefd8f0000 4791adc3 Jan 19 02:58:59 2008 C:\Windows\system32\credssp.dll 7fefd4b0000 49e041f1 Apr 11 03:08:33 2009 C:\Windows\system32\schannel.dll 7fefdfc0000 49e041a5 Apr 11 03:07:17 2009 C:\Windows\system32\NETAPI32.dll 7fefbc50000 49e04225 Apr 11 03:09:25 2009 c:\windows\system32\webclnt.dll 7fefba50000 49e04251 Apr 11 03:10:09 2009 c:\windows\system32\WINHTTP.dll 7fefedc0000 49e041f4 Apr 11 03:08:36 2009 C:\Windows\system32\SHLWAPI.dll 7fefe4b0000 49e04209 Apr 11 03:08:57 2009 C:\Windows\system32\urlmon.dll 7fefe8d0000 49e04146 Apr 11 03:05:42 2009 C:\Windows\system32\iertutil.dll 7fefcc80000 49e041e9 Apr 11 03:08:25 2009 C:\Windows\WinSxS\amd64_microsoft.windows.common-controls_6595b64144ccf1df_6.0.6002.18005_none_1509f8bef40ee4da\comctl32.dll 7feff000000 49e041ef Apr 11 03:08:31 2009 C:\Windows\system32\shell32.dll 7feffc60000 49e04252 Apr 11 03:10:10 2009 C:\Windows\system32\WinInet.dll 77e50000 4549b4d2 Nov 02 05:05:22 2006 C:\Windows\system32\Normaliz.dll 7fefbc10000 4791ae1c Jan 19 03:00:28 2008 c:\windows\system32\wkssvc.dll 7fefda40000 49e04193 Apr 11 03:06:59 2009 c:\windows\system32\IPHLPAPI.DLL 7fefd9f0000 49e040f3 Apr 11 03:04:19 2009 c:\windows\system32\dhcpcsvc.DLL 7fefdd00000 49e04119 Apr 11 03:04:57 2009 c:\windows\system32\DNSAPI.dll 7fefd9e0000 4791ae08 Jan 19 03:00:08 2008 c:\windows\system32\WINNSI.DLL 7fefd9b0000 49e040f4 Apr 11 03:04:20 2009 c:\windows\system32\dhcpcsvc6.DLL 7fefdc90000 4791adef Jan 19 02:59:43 2008 c:\windows\system32\NTDSAPI.dll 7fefd5a0000 4791adf5 Jan 19 02:59:49 2008 c:\windows\system32\WINBRAND.dll 7fefb7d0000 4549d27e Nov 02 07:11:58 2006 c:\windows\system32\fdrespub.dll 7fefb500000 49e0423a Apr 11 03:09:46 2009 c:\windows\system32\wsdapi.dll 7fefb810000 4791ad11 Jan 19 02:56:01 2008 c:\windows\system32\HTTPAPI.dll 7fefd3a0000 4791ae1a Jan 19 03:00:26 2008 c:\windows\system32\WINTRUST.dll 7fefe400000 4791ad46 Jan 19 02:56:54 2008 C:\Windows\system32\imagehlp.dll 7fefcfc0000 4791addb Jan 19 02:59:23 2008 c:\windows\system32\XmlLite.dll 7fefd290000 4791ace8 Jan 19 02:55:20 2008 c:\windows\system32\FirewallAPI.dll 7fefd820000 49e04210 Apr 11 03:09:04 2009 c:\windows\system32\VERSION.dll 7fefb280000 49e0411b Apr 11 03:04:59 2009 C:\Windows\system32\FunDisc.dll 7fefc840000 4791ac8a Jan 19 02:53:46 2008 C:\Windows\system32\ATL.DLL 7fefe9a0000 49e041ed Apr 11 03:08:29 2009 C:\Windows\system32\SETUPAPI.dll 7fefd790000 49e0418f Apr 11 03:06:55 2009 C:\Windows\system32\mswsock.dll 7fefd400000 4791aeae Jan 19 03:02:54 2008 C:\Windows\System32\wshtcpip.dll 7fefd810000 4791aea8 Jan 19 03:02:48 2008 C:\Windows\System32\wship6.dll 7fefacc0000 49e04191 Apr 11 03:06:57 2009 C:\Windows\System32\msxml3.dll 7fefb140000 4791ae0e Jan 19 03:00:14 2008 c:\windows\system32\ssdpsrv.dll 7fefafa0000 49e0420a Apr 11 03:08:58 2009 c:\windows\system32\w32time.dll 7fefdd40000 4791adc8 Jan 19 02:59:04 2008 c:\windows\system32\cryptdll.dll 7fefd3e0000 49e04118 Apr 11 03:04:56 2009 C:\Windows\system32\GPAPI.dll 7fefdae0000 49e041da Apr 11 03:08:10 2009 C:\Windows\system32\slc.dll 7fefb100000 49ee93d7 Apr 21 23:49:43 2009 C:\Windows\System32\vmictimeprovider.dll 7fefa300000 4791ad84 Jan 19 02:57:56 2008 c:\windows\system32\netprofm.dll 7fefc900000 4791ad8c Jan 19 02:58:04 2008 c:\windows\system32\nlaapi.dll 7fefa2a0000 4791adbc Jan 19 02:58:52 2008 c:\windows\system32\upnphost.dll 7fefb3f0000 4549d324 Nov 02 07:14:44 2006 c:\windows\system32\SSDPAPI.dll 7fefaf90000 4549d36c Nov 02 07:15:56 2006 C:\Windows\System32\npmproxy.dll 7fefe070000 4791adb4 Jan 19 02:58:44 2008 C:\Windows\system32\SXS.DLL 7fefce90000 4791acf3 Jan 19 02:55:31 2008 c:\windows\system32\fdphost.dll 7fef69c0000 49e04124 Apr 11 03:05:08 2009 C:\Windows\system32\fdwsd.dll 7fef6980000 4791ad25 Jan 19 02:56:21 2008 C:\Windows\system32\MLANG.dll 7fef6960000 49e04121 Apr 11 03:05:05 2009 C:\Windows\system32\fdssdp.dll 7fefd020000 49e0411f Apr 11 03:05:03 2009 C:\Windows\system32\fdproxy.dll 7fefb840000 4791ad5c Jan 19 02:57:16 2008 C:\Windows\system32\napinsp.dll 7fef97d0000 4791adb8 Jan 19 02:58:48 2008 C:\Windows\system32\pnrpnsp.dll 7fefb860000 4791ae09 Jan 19 03:00:09 2008 C:\Windows\System32\winrnr.dll 7fef9660000 4791ad9a Jan 19 02:58:18 2008 C:\Windows\system32\rasadhlp.dll

 

Note how neither process has MSRDC.DLL loaded either. It’s simply not being used, and a module that is not being used cannot possibly affect anyone. Remember, an application has to be coded to use RDC. Nothing in the Kernel, in Robocopy, or in the Workstation service uses RDC at all in Vista or Win7.

Still don’t believe me? Here is the Microsoft Remote File Systems development team stating it as well.

Changes that can truly improve file copy performance

By now you want me to get to the helpful part. Here’s a short list of some things that can improve your file copy network performance on Windows Vista and Windows Server 2008:

  • Install Service Pack 2
  • Install the latest NIC drivers from your vendor.
  • Try disabling Receive Side Scaling, Chimney Offload, and NetDMA support, then testing like I did above to see if the results are measurably different after many copies of the same file. Note that this just disables the Windows implementation of those components – your vendor may also support them through their NIC configuration and it will need to be turned off there as well. While these components are intended to help performance, mileage can vary based on how good your hardware and vendor drivers are.
  • Use robocopy.exe rather than Explorer – the price of the friendly shell showing progress and browsing folders is slightly slower performance.

Wrapup

It’s amazing that a component that was designed to speed up network file performance can somehow be vilified as a cause of bad performance; especially when it’s not even being used. I welcome people following my steps and telling me what you find out.

Don’t believe everything you read on the Internet. Unless I wrote it. :-)

- Ned ‘Rick Rolled’ Pyle