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Browsing DFS gradually slows

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Browsing DFS gradually slows

Postby chicagotech » Thu Mar 20, 2008 9:58 am

WS2003 R2 SP2 domain and file servers. Domain DFS folders are hosted on
various servers. Antivirus is SAV CE, which is reportedly

When browsing DFS folders with Explorer from Win XP SP2 or WS2003 R2 SP2,
all fully patched via WSUS, initial response is instant. But as you continue
navigating through folders--within the same DFS share or between DFS
shares--Explorer takes longer and longer to enumerate folder contents. It
first becomes very noticeable after browsing perhaps 8-10 folders, and it
keeps getting worse as you continue to browse. Eventually, it can take a
couple minutes to view a folder.

When this happens, if you click Start/Run, it can take a minute or two for
the dialog box to appear. Thereafter, when you type in the "Open" field,
there is a pause of 2 or 3 seconds between display of each character.
Likewise, typing a path in the Explorer Address Bar results in a pause
between each character.

Browsing the non-DFS share is fast regardless of how many folders are
browsed, except that once DFS browsing has slowed down Explorer, Explorer is
slow browsing anywhere, including local drives.

There's no correlation between the problem and specific servers. Browsing
any DFS share will do it.

CMD sessions are always fast, whether DFS or not, regardless of the state of

Browsing the DFS Root level of the namespace is fast, regardless of the
state of Explorer.

File operations within applications don't slow down, except for browsing in
common file dialogs.

Usually, when Explorer is slowed down, if you close an Explorer window, the
window closes, but its Taskbar button remains indefinitely. When you log
off, Windows reports Explorer is hung and you have to End Task to log off.

Within the Windows session, if you force Explorer closed with Task
Manager/Processes, and restart Explorer, it runs normally until I browse
many DFS folders again.

- I started doing the items on your list. The problem is definitely associated
with the virus scanner, SAV CE 10.1.5. When I stop the virus scanner service
on the client, the problem no longer occurs. When I start the service, the
problem occurs.

On Symantec's SAV KB, I searched for "DFS slow". Symantec recommended MS
hotfix KB906866. It's included in WS2003 SP2, so I added the DfsIrpStackSize
registry setting on a WS2003 SP2 machine, but it did not make any
difference. FWIW, we only have one file system anitvirus, SAV CE, so unless
we have more file system filters for some other reason, I don't think it's
applicable anyway.

I'm sure you're going to refer me to Symantec at this point, but if you have
any insight as to another hotfix or anything else I might try, please let me


- 1. This issue may occur because of an error in the Twext.dll file. When
this error occurs, the client computer sends many referral requests to the
DFS server after you try to access shared files. To check the issue:
For WinXP machines, please install hotfix (KB941133). I'd like to share
with you the "hotfix online submission" service that you can use to request
this hotfix <ID>:
http://support.microsoft.com/gp/CUHotFi ... ge_Request.

After completing the relevant info (such as KB ID, product and language)
and providing a valid email address, please click the Submit button. A
Microsoft professional will respond to you via e-mail within 8 business

For Win2003 machines, please install the update directly from the following
925066 In a domain environment, Windows Explorer may stop responding on a
client computer that is running Windows XP or Windows Server 2003, and CPU
usage is very high on the primary domain controller
http://support.microsoft.com/default.as ... -US;925066

2. Please temporarily remove all the shortsut links in the DFS share. These
cause shell32.dll to resolve the targets for each shortcut, from some
machines they were invalid paths.

3. I under your Antivirus software is compatible with DFS. As there are
known issues that AV scan causing DFS browsing slow. I suggest we
temporarily disable/uninstall the antivirus software from your client to
quickly identify the issue.

4. Please check whether the problem occurs if you use Mapped Drive to
access the DFS share instead of UNC connections.
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