Pitfalls of antivirus programs

by Miha Markič 1. March 2007 15:32

One has to be careful when using an antivirus application that protects computer in real time (scans files when one opens them). Here is what happened. I am working on a project for a customer of mine. For source file control we use Visual SourceSafe over VPN. I won't discuss further whether this is an ideal combination... It actually performs good enough even though the line is relatively slow. However, one day it became dead slow. By dead slow I mean half an hour to open an project and 2+ hours to get latest version. I immediately suspected Internet provider and transfer speed over Internet. Yet, this wasn't it - it was working normally on another computer of mine.

So I start thinking what did change on my computer in last week or so. After exactly 5s of deep thinking I had a revelation - I installed an antivirus system a week or so ago. Combine it with VSS over VPN and you have an unresponsive VSS client. However, the problem is not within this particular antivirus application. The problem is in the VSS itself. VSS is just a file server, meaning that everything is done on the client - actually there is no such thing as VSS server (there is some thin layer when using VSS2005 over Internet). And knowing that VSS usually produces a myriad of small files I immediately figured it out what's going on - VSS client has to check a ton of these files and each file is checked by antivirus application in real time - thus totally killing the performance (multiplying * x access on each file over VPN).

The solution was simple - I disabled real time monitor for network files and VSS started to perform normally again.

Tags:

Windows | .net

Comments (6) -

Mladen
Mladen
3/1/2007 10:36:08 PM #

What antivirus do you have?
we have nod32 and a VPN to germany and it works with no problem.

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Miha Markic
Miha Markic
3/1/2007 11:00:50 PM #

Yes, I installed NOD32, too. However, note that I am on slow VPN, slow mean something like 384/384Kbps.

But let me emphasize that this isn't a NOD32 related problem. It is how antivirus applictions work in general when protecting system in real time. Actually I think that NOD32 is an excellent antivirus.

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Peter Ritchie
Peter Ritchie
3/2/2007 12:59:02 AM #

It would be nice, in NOD32 to be able to add a network path to the exclusion list rather than disable all network checking...  Oh well.

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Miha Markic
Miha Markic
3/2/2007 1:58:02 AM #

Hi Peter,

Exactly. Actually I first tried path exclusion but it didn't work.

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Matej
Matej
3/2/2007 2:26:00 PM #

Or change VSS with SVN/Subversion. There is also good windows client named tortoisesvn.

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Miha Markic
Miha Markic
3/2/2007 3:05:49 PM #

Hi Matej,

Yes, I know - either subversion or Team Foundation. However, client runs the game.

Reply

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Miha Markic

About me
Righthand
 
Microsoft MVP
 
Developer Express' DXSquad
INETA Country Leader for Slovenia
INETA Country Leader for Slovenia

Slovene Developer Users Group Lead
Friends of Red-Gate
LLBLGenPro Partner

Miha currently works as a free lance consultant and software developer specialized in .net area.
He graduated in Computer and information science at the University of Ljubljana, Slovenia. He has accumulated experience in various programming languages such as Java, Visual Basic 3-6 (MCP), Visual C++, Delphi, C# and VB.Net through years.
He has experience in practically all (technical) stages of project development, including planning, framework development, user interface, business processes, as well as testing and documenting. He has worked on big and small projects in Slovenia and abroad (e.g. participated in completing level 3 IS for the Nucor steel plant, Hertford, USA).
Currently he enjoys programming in .net environment using C#. Since 2000 he has been active in Developer Express' DX Squad and has been ECDL trainer and tester. He also gives lectures on conferences and other events in Slovenia.

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