Avast and Network Copy Performance?

[Amorphous_Snake]

I have somewhat the same problem.

I have 4 PCs:
PC1 and PC2 have Windows Vista Business SP1 with Avast 4.8 updated to the latest version
PC3 has Windows XP Professional SP3 also with Avast 4.8 updated to the latest version
PC4 has Mandriva 2008.1 (that's my file server)

All the PCs are connected via Cat5e cables using a 100 Mbps D-Link switch. All Windows PCs have ZoneAlarm while Mandriva has its firewall disabled by me.

Copying a file from Vista to Vista gives me 99% speed (11.5 MB/s or so), that's with Avast turned on or off.

Copying a file from XP or Mandriva to Vista (with Avast turned on), I get 60-80% speed.

Copying a file from XP or Mandriva to Vista (with Avast turned off), I get 99% speed.

I need to make some things clear:
- The files I am copying are variable, from a 9 GB folder of 180 MB files each, to a 20 GB folder of 2-3 MB files each. Or a single 300 MB file, or a single 8 GB file. I have tried lots of things!!!
- The Vista machines are newer (Core 2 Duo E8400 and 2 GB RAM). While the other 2 are older P3 and P4.
- Switching ZoneAlarm on or off doesn't do anything.
- Disabling Avast in the XP machine while copying, doesn't affect the speeds, when copying from it. Disabling Avast from Vista and then copying from XP speeds up thing (like I said above).

What's wrong?

I think that Avast tries to scan the files from the source, but since the source are older machines, they slow down things? That's why I have no problems in the Vista machines because they are newer?!

[Edit]: I added that the network is 100 Mbps.

[rbeane]

Watch the last scanned on the screen.  What I see is that avast scans the source file twice; once on the source and again on the target.

[rangerevo8]

Copying a file from Vista to Vista gives me 99% speed (11.5 MB/s or so), that's with Avast turned on or off.

This is not always true.
I had 2 PC with Vista 32 Ultimate linked on a 100Mbps network as well. I had notice network problem (slow, hang or timeout etc) since i changed my OS to Vista.

At first, I was though its purely Vista problem. So i did tried  to disable many things.. (Remote Differential Compression, Vista Auto-Tuning, User Acount Control (UAC) etc.) All had either No or Less affect on my network copy speed.

Then, i started to think about avast.
First, I had stopped avast On-Access Protection (all 7 providers) on my Source PC and tested out the network copy/browsing activity was still SLOW.
Secondly, I stopped avast On-Access Protection (all 7 providers) on my Destination PC and found network copy/browsing activity is normal and able to run at Full Speed. (NOTE: avast On-Access Protection is running on Source PC)

However, i found out that this not happen permenantly as i tried to Restart my both PC, network copy/browsing activity is still normal EVEN avast On-Access Protection is running on both PC. I was suspecting that this only happen after Network is too busy for sometime (overflow or something) and the problem started to appear.

It seems that this problem is caused by either VISTA or AVAST program. I can just hope the developers or any pro can figure out and solve the problem.

I was now try to permenantly disable avast Network Sheild to see if this can solve my problem.

[rbeane]

My network shield is always disabled and it happens.  My results are consistent and reproducible....See original posts.

Why doesn't this thread get any developer response?

[Vlk]

Stuck@home,

I think your conclusion is +- correct: the slowdown is caused by the fact that avast is scanning the destination file (once it's closed) and this effectively causes the file to be transmitted over your slow connection once more (the actual scan is fast, but to actually pull the data from the remote host is expensive).

I noticed that you have asked, repeatedly, why is avast scanning the file "twice" (i.e. on both source and target). The answer is, how are we supposed to know that these are the same files?

I mean, this is a file copy, but what if the file was being slightly modified during the operation? Etc....
Basically, there's no way for us to conclude that the file has already been scanned I'm afraid... or do you have any suggestions? I'd be certainly interested in some bright ideas...

BTW AFAIK all other AV products behave the same way...


Thanks
Vlk

[rbeane]

First off, thanks for the response.  While I understand what you are saying, it appears according to other posts that avast behaves differently on XP vs. Vista with respect to this.  See below. 

I don't have Vista, nor a wireless network, but I do have three XP machines on an ethernet (hard wire) network, via a router. One of the PC's is XP-Home SP2, one is XP-Home SP3, one is XP-Pro SP3.

I have Zone Alarm firewall on all of them primarily to look after outgoing - the firewall in the router is the primary for incoming. All three have Avast 4.8.1229, with the Standard shield set to High. All three have Spybot 1.6 fully immunised. Two of the three have Teatimer (the latest beta version) active.

I don't see the double scan you are talking about. Regardless of which PC the copy/paste is initiated from, the scan appears to be only being carried out by Avast on the machine the file is being copied to.

Does it slow down a file transfer - yes, but certainly not to an unacceptable degree. It's a bit like pouring tea from the teapot to the cup - if you use a fine wire strainer, it is slower and so takes longer, but the advantage is you don't have to put up with tea leaves in your cup.

[Vlk]

It depends on the file type etc. But generally (especially when the Standard Shield sensitivity is set to High) we scan both the source and the target copy. And this applies to both XP and Vista.

Thanks
Vlk

[rbeane]

As I mentioned these details earlier in the thread, the files were 2-5MB jpg pictures and the standard shield is set to normal.  File copy performance was cut in half.

It depends on the file type etc. But generally (especially when the Standard Shield sensitivity is set to High) we scan both the source and the target copy. And this applies to both XP and Vista.

So why did olddog not see the src file being scan under XP as quoted in my last post.

[Vlk]

Let's try one thing.

Open Standard Shield's settings, go to the Advanced page, and in the list of scan exclusions, insert this:

<W>\\*


Confirm with OK and see if it makes any difference.

Thanks
Vlk

[rbeane]

Adding the "<W>\\*" didn't affect anything and still scanned the remote workstation file and the destination file and still cut performance in half vs. standard shield off. 900KB/sec vs 2.3MB/sec with Standard shield off.  It was essentially ignored.

Adding "\\Workstation_name\*" performed virtually the same as if the standard shield was off. 2.3MB/sec copy rate.  Also when "\\Workstation_name\*" was set as an exclusion, only the destination file was scanned.

Again reinterated what has already posted in this thread, it seems avast under XP with the standard shield scans only the target file on a copy whereas Vista scans both on normal.

Copy performed was an entire folder of 55 jpg files ranging from  3 to 5MB. Standard Shield set to normal when on.

[Vlk]

Adding "\\Workstation_name\*" performed virtually the same as if the standard shield was off. 2.3MB/sec copy rate.  Also when "\\Workstation_name\*" was set as an exclusion, only the destination file was scanned.

Now I'm not sure I understand. I thought the destination was the remote server (\\workstation_name)...

[rbeane]

No, copying from a remote server(actually workstation) to the computer I am on.

So from Laptop1, I open the shared directory through vista network link off start menu, then select the remote Laptop(laptop2).  Browse to the Pictures directory I want to copy from Laptop2 and copy then paste to Laptop1 the directory. 

Results
1. With standard shield off on Laptop1, throughput is 2.3MB/sec. Obviously no scanning.

2. With Standard shield ON and Normal (no exclusions), throughput is 900KB/sec. Based on "show detailed info on scanning" set on Laptop1, both the src file(laptop2) and the dest file(laptop1) are scanned in that order.
 
3. With Standard shield On and Normal with \\* as an exclusion, throughput is 900KB/sec.  Based on "show detailed info on scanning" set on Laptop1, both the src file(laptop2) and the dest file(laptop1) are scanned in that order.

4. With Standard shield On and Normal with \\Laptop2\* as an exclusion, throughput is 2.3MB/sec.  Based on "show detailed info on scanning" set on Laptop1, only the dest file(laptop1) is scanned.

I am guessing it is pulling the file through the network scanning it then discarding it and pulling it through the network again, copying it and scanning it again. This behavior based on other user posts seems to be different on XP vs. Vista under the Normal setting.  According to another user, Avast under XP does scan the file twice under High setting, but not Normal.  I just want the same behavior.

BTW, I am not trying to be a pain, just trying to make a great product better.  I have been using Avast for over 4 years and have recommended it to many people over those years.  Thanks for a great product and especially for the efforts to make it better.

 

[rbeane]

Did my last post explain it so you can understand better?